@article{51339, author = {{Babai-Hemati, Jonas and vom Bruch, Felix and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, publisher = {{Optica Publishing Group}}, title = {{{Tailored second harmonic generation inTi-diffused PPLN waveguides usingmicro-heaters}}}, doi = {{10.1364/oe.510319}}, year = {{2024}}, } @article{36471, abstract = {{Superconducting nanowire single-photon detectors (SNSPDs) show near unity efficiency, low dark count rate, and short recovery time. Combining these characteristics with temporal control of SNSPDs broadens their applications as in active de-latching for higher dynamic range counting or temporal filtering for pump-probe spectroscopy or LiDAR. To that end, we demonstrate active gating of an SNSPD with a minimum off-to-on rise time of 2.4 ns and a total gate length of 5.0 ns. We show how the rise time depends on the inductance of the detector in combination with the control electronics. The gate window is demonstrated to be fully and freely, electrically tunable up to 500 ns at a repetition rate of 1.0 MHz, as well as ungated, free-running operation. Control electronics to generate the gating are mounted on the 2.3 K stage of a closed-cycle sorption cryostat, while the detector is operated on the cold stage at 0.8 K. We show that the efficiency and timing jitter of the detector is not altered during the on-time of the gating window. We exploit gated operation to demonstrate a method to increase in the photon counting dynamic range by a factor 11.2, as well as temporal filtering of a strong pump in an emulated pump-probe experiment.}}, author = {{Hummel, Thomas and Widhalm, Alex and Höpker, Jan Philipp and Jöns, Klaus and Chang, Jin and Fognini, Andreas and Steinhauer, Stephan and Zwiller, Val and Zrenner, Artur and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{1}}, publisher = {{Optica Publishing Group}}, title = {{{Nanosecond gating of superconducting nanowire single-photon detectors using cryogenic bias circuitry}}}, doi = {{10.1364/oe.472058}}, volume = {{31}}, year = {{2023}}, } @article{45704, abstract = {{Since high-order harmonic generation (HHG) from atoms depends sensitively on the polarization of the driving laser field, the polarization gating (PG) technique was developed and applied successfully to generate isolated attosecond pulses from atomic gases. The situation is, however, different in solid-state systems as it has been demonstrated that due to collisions with neighboring atomic cores of the crystal lattice strong HHG can be generated even by elliptically- and circularly-polarized laser fields. Here we apply PG to solid-state systems and find that the conventional PG technique is inefficient for the generation of isolated ultrashort harmonic pulse bursts. In contrast, we demonstrate that a polarization-skewed laser pulse is able to confine the harmonic emission to a time window of less than one-tenth of the laser cycle. This method provides a novel way to control HHG and to generate isolated attosecond pulses in solids.}}, author = {{Song, Xiaohong and Yang, Shidong and Wang, Guifang and Lin, Jianpeng and Wang, Liang and Meier, Torsten and Yang, Weifeng}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{12}}, publisher = {{Optica Publishing Group}}, title = {{{Control of the electron dynamics in solid-state high harmonic generation on ultrafast time scales by a polarization-skewed laser pulse}}}, doi = {{10.1364/oe.491418}}, volume = {{31}}, year = {{2023}}, } @article{45850, abstract = {{Interference between single photons is key for many quantum optics experiments and applications in quantum technologies, such as quantum communication or computation. It is advantageous to operate the systems at telecommunication wavelengths and to integrate the setups for these applications in order to improve stability, compactness and scalability. A new promising material platform for integrated quantum optics is lithium niobate on insulator (LNOI). Here, we realise Hong-Ou-Mandel (HOM) interference between telecom photons from an engineered parametric down-conversion source in an LNOI directional coupler. The coupler has been designed and fabricated in house and provides close to perfect balanced beam splitting. We obtain a raw HOM visibility of (93.5 ± 0.7) %, limited mainly by the source performance and in good agreement with off-chip measurements. This lays the foundation for more sophisticated quantum experiments in LNOI.}}, author = {{Babel, Silia and Bollmers, Laura and Massaro, Marcello and Luo, Kai Hong and Stefszky, Michael and Pegoraro, Federico and Held, Philip and Herrmann, Harald and Eigner, Christof and Brecht, Benjamin and Padberg, Laura and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{14}}, publisher = {{Optica Publishing Group}}, title = {{{Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler}}}, doi = {{10.1364/oe.484126}}, volume = {{31}}, year = {{2023}}, } @article{46644, abstract = {{A reliable, but cost-effective generation of single-photon states is key for practical quantum communication systems. For real-world deployment, waveguide sources offer optimum compatibility with fiber networks and can be embedded in hybrid integrated modules. Here, we present what we believe to be the first chip-size fully integrated fiber-coupled heralded single photon source (HSPS) module based on a hybrid integration of a nonlinear lithium niobate waveguide into a polymer board. Photon pairs at 810 nm (signal) and 1550 nm (idler) are generated via parametric down-conversion pumped at 532 nm in the LiNbO3 waveguide. The pairs are split in the polymer board and routed to separate output ports. The module has a size of (2 × 1) cm^2 and is fully fiber-coupled with one pump input fiber and two output fibers. We measure a heralded second-order correlation function of g_h(2)=0.05 with a heralding efficiency of η_h=3.5% at low pump powers}}, author = {{Kießler, Christian and Conradi, Hauke and Kleinert, Moritz and Quiring, Viktor and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{14}}, publisher = {{Optica Publishing Group}}, title = {{{Fiber-coupled plug-and-play heralded single photon source based on Ti:LiNbO3 and polymer technology}}}, doi = {{10.1364/oe.487581}}, volume = {{31}}, year = {{2023}}, } @article{48349, abstract = {{We report a titanium indiffused waveguide resonator featuring an integrated electro-optic modulator for cavity length stabilisation that produces close to 5 dB of squeezed light at 1550 nm (2.4 dB directly measured). The resonator is locked on resonance for tens of minutes with 70 mW of SH light incident on the cavity, demonstrating that photorefraction can be mitigated. Squeezed light production concurrent with cavity length stabilisation utilising the integrated EOM is demonstrated. The device demonstrates the suitability of this platform for squeezed light generation in network applications, where stabilisation to the reference field is typically necessary.}}, author = {{Stefszky, M. and vom Bruch, F. and Santandrea, M. and Ricken, R. and Quiring, V. and Eigner, C. and Herrmann, H and Silberhorn, C}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{21}}, publisher = {{Optica Publishing Group}}, title = {{{Lithium niobate waveguide squeezer with integrated cavity length stabilisation for network applications}}}, doi = {{10.1364/oe.498423}}, volume = {{31}}, year = {{2023}}, } @article{48399, abstract = {{Quantum photonic processing via electro-optic components typically requires electronic links across different operation environments, especially when interfacing cryogenic components such as superconducting single photon detectors with room-temperature control and readout electronics. However, readout and driving electronics can introduce detrimental parasitic effects. Here we show an all-optical control and readout of a superconducting nanowire single photon detector (SNSPD), completely electrically decoupled from room temperature electronics. We provide the operation power for the superconducting detector via a cryogenic photodiode, and readout single photon detection signals via a cryogenic electro-optic modulator in the same cryostat. This method opens the possibility for control and readout of superconducting circuits, and feedforward for photonic quantum computing.}}, author = {{Thiele, Frederik and Hummel, Thomas and McCaughan, Adam N. and Brockmeier, Julian and Protte, Maximilian and Quiring, Victor and Lengeling, Sebastian and Eigner, Christof and Silberhorn, Christine and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{20}}, publisher = {{Optica Publishing Group}}, title = {{{All optical operation of a superconducting photonic interface}}}, doi = {{10.1364/oe.492035}}, volume = {{31}}, year = {{2023}}, } @article{29716, author = {{Widhalm, Alex and Golla, Christian and Weber, Nils and Mackwitz, Peter and Zrenner, Artur and Meier, Cedrik}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{4}}, publisher = {{The Optical Society}}, title = {{{Electric-field-induced second harmonic generation in silicon dioxide}}}, doi = {{10.1364/oe.443489}}, volume = {{30}}, year = {{2022}}, } @article{31329, abstract = {{Highly directive antennas with the ability of shaping radiation patterns in desired directions are essential for efficient on-chip optical communication with reduced cross talk. In this paper, we design and optimize three distinct broadband traveling-wave tantalum pentoxide antennas exhibiting highly directional characteristics. Our antennas contain a director and reflector deposited on a glass substrate, which are excited by a dipole emitter placed in the feed gap between the two elements. Full-wave simulations in conjunction with global optimization provide structures with an enhanced linear directivity as high as 119 radiating in the substrate. The high directivity is a result of the interplay between two dominant TE modes and the leaky modes present in the antenna director. Furthermore, these low-loss dielectric antennas exhibit a near-unity radiation efficiency at the operational wavelength of 780 nm and maintain a broad bandwidth. Our numerical results are in good agreement with experimental measurements from the optimized antennas fabricated using a two-step electron-beam lithography, revealing the highly directive nature of our structures. We envision that our antenna designs can be conveniently adapted to other dielectric materials and prove instrumental for inter-chip optical communications and other on-chip applications.}}, author = {{Farheen, Henna and Yan, Lok-Yee and Quiring, Viktor and Eigner, Christof and Zentgraf, Thomas and Linden, Stefan and Förstner, Jens and Myroshnychenko, Viktor}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_opticalantenna}}, number = {{11}}, pages = {{19288}}, publisher = {{Optica Publishing Group}}, title = {{{Broadband optical Ta2O5 antennas for directional emission of light}}}, doi = {{10.1364/oe.455815}}, volume = {{30}}, year = {{2022}}, } @article{34235, abstract = {{We demonstrate for the first time, to the best of our knowledge, reconfigurable and real-time orthogonal time-domain detection of a high-bandwidth Nyquist signal with a low-bandwidth silicon photonics Mach-Zehnder modulator based receiver. As the Nyquist signal has a rectangular bandwidth, it can be multiplexed in the wavelength domain without any guardband as a part of a Nyquist-WDM superchannel. These superchannels can be additionally multiplexed in space and polarization. Thus, the presented demonstration can open a new possibility for the detection of multidimensional parallel data signals with silicon photonics. No external pulse source is needed for the receiver, and frequency-time coherence is used to sample the incoming Nyquist signal with orthogonal sinc-shaped Nyquist pulse sequences. All parameters are completely tunable in the electrical domain. The feasibility of the scheme is demonstrated through a proof-of-concept experiment over the entire C-band (1530 nm–1560 nm), employing a 24 Gbaud Nyquist QPSK signal due to experimental constraints on the transmitter side electronics. However, the silicon Mach-Zehnder modulator with a 3-dB bandwidth of only 16 GHz can process Nyquist signals of 90 GHz optical bandwidth, suggesting a possibility to detect symbol rates up to 90 GBd in an integrated Nyquist receiver.}}, author = {{Misra, Arijit and Kress, Christian and Singh, Karanveer and Meier, Janosch and Schwabe, Tobias and Preussler, Stefan and Scheytt, J. Christoph and Schneider, Thomas}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{8}}, publisher = {{Optica Publishing Group}}, title = {{{Reconfigurable and real-time high-bandwidth Nyquist signal detection with low-bandwidth in silicon photonics}}}, doi = {{10.1364/oe.454163}}, volume = {{30}}, year = {{2022}}, } @article{34230, abstract = {{We present the design and experimental characterization of a silicon nitride pulse interleaver based on coupled resonator optical waveguide filters. In order to achieve a targeted free spectral range of 1.44 THz, which is large given the reduced optical confinement of the silicon nitride platform, individual ring resonators are designed with tapered waveguides. Its application to time-interleaved photonically-assisted ADCs is analyzed by combining experimental characterization of the photonic integrated circuit with a comprehensive model of the entire ADC. The impact of fundamental signal distortion and noise sources affecting the converter is investigated and suitable equalization techniques at the digital signal processing level are evaluated. The novel application of a simple but powerful equalization filter in the DSP domain allows for a significant improvement of the digitized signal SNR. An ENOB of 5 over a 75 GHz bandwidth (150 GS/s) and an ENOB of 4.3 over a 100 GHz bandwidth (200 GS/s) are expected to be achievable with compact and off-the-shelf single-section semiconductor mode locked lasers, that can be further improved with lower noise light sources.}}, author = {{Zazzi, Andrea and Müller, Juliana and Ghannam, Ibrahim and Battermann, Moritz and Rajeswari, Gayatri Vasudevan and Weizel, Maxim and Scheytt, J. Christoph and Witzens, Jeremy}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{3}}, publisher = {{Optica Publishing Group}}, title = {{{Wideband SiN pulse interleaver for optically-enabled analog-to-digital conversion: a device-to-system analysis with cyclic equalization}}}, doi = {{10.1364/oe.441406}}, volume = {{30}}, year = {{2022}}, } @article{34232, abstract = {{In this paper, the theory of phase-locking of a microwave oscillator on the interharmonics, i.e. non-integer harmonics, of the repetition rate of the optical pulse train of a mode-locked laser (MLL) is developed. A balanced optical microwave phase detector (BOMPD) is implemented using a balanced Mach-Zehnder modulator and is employed to discriminate the phase difference between the envelope of the optical pulses and the microwave oscillator. It is shown mathematically that the inherent nonlinear properties of BOMPD with respect to the microwave excitation amplitude can be used for interharmonic locking. The characteristic functions of the phase detector for interharmonic locking are derived analytically and are compared with the measurement results. An opto-electronic phase-locked loop (OEPLL) is demonstrated whose output frequency locks on interharmonics of the MLL repetition rate when an appropriate modulator bias and sufficient RF amplitude are applied. Thus, for the first time theory and experiment of reliable locking on interharmonics of the repetition rate of a MLL are presented.}}, author = {{Bahmanian, Meysam and Kress, Christian and Scheytt, J. Christoph}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{5}}, publisher = {{Optica Publishing Group}}, title = {{{Locking of microwave oscillators on the interharmonics of mode-locked laser signals}}}, doi = {{10.1364/oe.451894}}, volume = {{30}}, year = {{2022}}, } @article{47980, abstract = {{Recently, ferroelectric domain walls (DWs) have attracted considerable attention due to their intrinsic topological effects and their huge potential for optoelectronic applications. In contrast, many of the underlying physical properties and phenomena are not well characterized. In this regard, analyzing the vibrational properties, e.g. by Raman spectroscopy, provides direct access to the various local material properties, such as strains, defects or electric fields. While the optical phonon spectra of DWs have been widely investigated in the past, no reports on the acoustic phonon properties of DWs exist. In this work, we present a joint Raman and Brillouin visualization of ferroelectric DWs in the model ferroelectric lithium niobate. This is possible by using a combined Raman and virtually imaged phased array Brillouin setup. Here, we show that DWs can be visualized via frequency shifts observed in the acoustic phonons, as well. The observed contrast then is qualitatively explained by models adapted from Raman spectroscopy. This work, hence, provides a novel route to study ferroelectric DWs and their intrinsic mechanical properties.}}, author = {{Rix, Jan and Rüsing, Michael and Galli, Roberta and Golde, Jonas and Reitzig, Sven and Eng, Lukas M. and Koch, Edmund}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{4}}, publisher = {{Optica Publishing Group}}, title = {{{Brillouin and Raman imaging of domain walls in periodically-poled 5%-MgO:LiNbO3}}}, doi = {{10.1364/oe.447554}}, volume = {{30}}, year = {{2022}}, } @article{21821, abstract = {{We present a combined experimental and numerical study of the far-field emission properties of optical travelling wave antennas made from low-loss dielectric materials. The antennas considered here are composed of two simple building blocks, a director and a reflector, deposited on a glass substrate. Colloidal quantum dots placed in the feed gap between the two elements serve as internal light source. The emission profile of the antenna is mainly formed by the director while the reflector suppresses backward emission. Systematic studies of the director dimensions as well as variation of antenna material show that the effective refractive index of the director primarily governs the far-field emission pattern. Below cut off, i.e., if the director’s effective refractive index is smaller than the refractive index of the substrate, the main lobe results from leaky wave emission along the director. In contrast, if the director supports a guided mode, the emission predominately originates from the end facet of the director.}}, author = {{Leuteritz, T. and Farheen, H. and Qiao, S. and Spreyer, F. and Schlickriede, Christian and Zentgraf, Thomas and Myroshnychenko, Viktor and Förstner, Jens and Linden, S.}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_opticalantenna}}, number = {{10}}, title = {{{Dielectric travelling wave antennas for directional light emission}}}, doi = {{10.1364/oe.422984}}, volume = {{29}}, year = {{2021}}, } @article{23476, author = {{Weizel, Maxim and Scheytt, J. Christoph and Kärtner, Franz X. and Witzens, Jeremy}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Optically clocked switched-emitter-follower THA in a photonic SiGe BiCMOS technology}}}, doi = {{10.1364/oe.425710}}, year = {{2021}}, } @article{37334, abstract = {{Uniaxial anisotropy in nonlinear birefringent crystals limits the efficiency of nonlinear optical interactions and breaks the spatial symmetry of light generated in the parametric down-conversion (PDC) process. Therefore, this effect is usually undesirable and must be compensated for. However, high gain may be used to overcome the destructive role of anisotropy in order to generate bright two-mode correlated twin-beams. In this work, we provide a rigorous theoretical description of the spatial properties of bright squeezed light in the presence of strong anisotropy. We investigate a single crystal and a system of two crystals with an air gap (corresponding to a nonlinear SU(1,1) interferometer) and demonstrate the generation of bright correlated twin-beams in such configurations at high gain due to anisotropy. We explore the mode structure of the generated light and show how anisotropy, together with crystal spacing, can be used for radiation shaping.}}, author = {{Riabinin, M. and Sharapova, Polina and Meier, Torsten}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{14}}, pages = {{21876--21890}}, publisher = {{Optica Publishing Group}}, title = {{{Bright correlated twin-beam generation and radiation shaping in high-gain parametric down-conversion with anisotropy}}}, doi = {{10.1364/oe.424977}}, volume = {{29}}, year = {{2021}}, } @article{47974, abstract = {{Domain walls (DWs) in ferroelectric (FE) and multiferroic materials possess an ever-growing potential as integrated functional elements, for instance in optoelectronic nanodevices. Mandatory, however, is the profound knowledge of the local-scale electronic and optical properties, especially at DWs that are still incompletely characterized to date. Here, we quantify the refractive index of individual FE DWs in periodically-poled LiNbO3 (PPLN) single crystals. When applying polarization-sensitive optical coherence tomography (PS-OCT) at 1300 nm using circular light polarization, we are able to probe the relevant electro-optical properties close to and at the DWs, including also their ordinary and extraordinary contributions. When comparing to numerical calculations, we conclude that the DW signals recorded for ordinary and extraordinary polarization stem from an increased refractive index of at least Δn > 2·10−3 that originates from a tiny region of < 30 nm in width. PS-OCT hence provides an extremely valuable tool to decipher and quantify subtle changes of refractive index profiles for both inorganic and biomedical nanomaterial systems.}}, author = {{Golde, Jonas and Rüsing, Michael and Rix, Jan and Eng, Lukas M. and Koch, Edmund}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{21}}, publisher = {{Optica Publishing Group}}, title = {{{Quantifying the refractive index of ferroelectric domain walls in periodically poled LiNbO3 single crystals by polarization-sensitive optical coherence tomography}}}, doi = {{10.1364/oe.432810}}, volume = {{29}}, year = {{2021}}, } @article{26223, author = {{Santandrea, Matteo and Stefszky, Michael and Roeland, Ganaël and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Interferometric method for determining the losses of spatially multi-mode nonlinear waveguides based on second harmonic generation}}}, doi = {{10.1364/oe.380788}}, year = {{2020}}, } @article{21024, author = {{Ansari, Vahid and Donohue, John M. and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{19}}, title = {{{Remotely projecting states of photonic temporal modes}}}, doi = {{10.1364/oe.395593}}, volume = {{28}}, year = {{2020}}, } @article{20372, abstract = {{A stepwise angular spectrum method (SASM) for curved interfaces is presented to calculate the wave propagation in planar lens-like integrated optical structures based on photonic slab waveguides. The method is derived and illustrated for an effective 2D setup first and then for 3D slab waveguide lenses. We employ slab waveguides of different thicknesses connected by curved surfaces to realize a lens-like structure. To simulate the wave propagation in 3D including reflection and scattering losses, the stepwise angular spectrum method is combined with full vectorial finite element computations for subproblems with lower complexity. Our SASM results show excellent agreement with rigorous numerical simulations of the full structures with a substantially lower computational effort and can be utilized for the simulation-based design and optimization of complex and large scale setups.}}, author = {{Ebers, Lena and Hammer, Manfred and Förstner, Jens}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_waveguides}}, number = {{24}}, pages = {{36361}}, title = {{{Light diffraction in slab waveguide lenses simulated with the stepwise angular spectrum method}}}, doi = {{10.1364/oe.409612}}, volume = {{28}}, year = {{2020}}, } @article{22771, author = {{Stefszky, Michael and Santandrea, Matteo and vom Bruch, Felix and Krapick, S. and Eigner, Christof and Ricken, R. and Quiring, V. and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Waveguide resonator with an integrated phase modulator for second harmonic generation}}}, doi = {{10.1364/oe.412824}}, year = {{2020}}, } @article{20157, author = {{Thiele, Frederik and vom Bruch, Felix and Quiring, Victor and Ricken, Raimund and Herrmann, Harald and Eigner, Christof and Silberhorn, Christine and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Cryogenic electro-optic polarisation conversion in titanium in-diffused lithium niobate waveguides}}}, doi = {{10.1364/oe.399818}}, year = {{2020}}, } @article{16301, author = {{Atorf, Bernhard and Mühlenbernd, Holger and Zentgraf, Thomas and Kitzerow, Heinz-Siegfried}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{6}}, pages = {{8898--8908}}, title = {{{All-optical switching of a dye-doped liquid crystal plasmonic metasurface}}}, doi = {{10.1364/oe.383877}}, volume = {{28}}, year = {{2020}}, } @article{20156, author = {{Schapeler, Timon and Höpker, Jan Philipp and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Quantum detector tomography of a 2×2 multi-pixel array of superconducting nanowire single photon detectors}}}, doi = {{10.1364/oe.404285}}, year = {{2020}}, } @article{37933, abstract = {{We present a time-over-threshold readout technique to count the number of activated pixels from an array of superconducting nanowire single photon detectors (SNSPDs). This technique places no additional heatload on the cryostat, and retains the intrinsic count rate of the time-tagger. We demonstrate proof-of-principle operation with respect to a four-pixel device. Furthermore, we show that, given some permissible error threshold, the number of pixels that can be reliably read out scales linearly with the intrinsic signal-to-noise ratio of the individual pixel response.}}, author = {{Tiedau, Johannes and Schapeler, Timon and Anant, Vikas and Fedder, Helmut and Silberhorn, Christine and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{4}}, publisher = {{Optica Publishing Group}}, title = {{{Single-channel electronic readout of a multipixel superconducting nanowire single photon detector}}}, doi = {{10.1364/oe.383111}}, volume = {{28}}, year = {{2020}}, } @article{38051, abstract = {{The characterisation of loss in optical waveguides is essential in understanding the performance of these devices and their limitations. Whilst interferometric-based methods generally provide the best results for low-loss waveguides, they are almost exclusively used to provide characterization in cases where the waveguide is spatially single-mode. Here, we introduce a Fabry-Pérot-based scheme to estimate the losses of a nonlinear (birefringent or quasi-phase matched) waveguide at a wavelength where it is multi-mode. The method involves measuring the generated second harmonic power as the pump wavelength is scanned over the phase matching region. Furthermore, it is shown that this method allows one to infer the losses of different second harmonic spatial modes by scanning the pump field over the separated phase matching spectra. By fitting the measured phase matching spectra from different titanium indiffused lithium niobate waveguides to the model presented in this paper, it is shown that one can estimate the second harmonic losses of a single spatial-mode, at wavelengths where the waveguides are spatially multi-mode.}}, author = {{Santandrea, Matteo and Stefszky, Michael and Roeland, Ganaël and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{4}}, publisher = {{Optica Publishing Group}}, title = {{{Interferometric method for determining the losses of spatially multi-mode nonlinear waveguides based on second harmonic generation.}}}, doi = {{10.1364/oe.380788}}, volume = {{28}}, year = {{2020}}, } @article{37932, abstract = {{Hybrid quantum information processing combines the advantages of discrete and continues variable protocols by realizing protocols consisting of photon counting and homodyne measurements. However, the mode structure of pulsed sources and the properties of the detection schemes often require the use of optical filters in order to combine both detection methods in a common experiment. This limits the efficiency and the overall achievable squeezing of the experiment. In our work, we use photon subtraction to implement the distillation of pulsed squeezed states originating from a genuinely spatially and temporally single-mode parametric down-conversion source in non-linear waveguides. Due to the distillation, we witness an improvement of 0.17 dB from an initial squeezing value of −1.648 ± 0.002 dB, while achieving a purity of 0.58, and confirm the non-Gaussianity of the distilled state via the higher-order cumulants. With this, we demonstrate the source’s suitability for scalable hybrid quantum network applications with pulsed quantum light.}}, author = {{Dirmeier, Thomas and Tiedau, Johannes and Khan, Imran and Ansari, Vahid and Müller, Christian R. and Silberhorn, Christine and Marquardt, Christoph and Leuchs, Gerd}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{21}}, publisher = {{Optica Publishing Group}}, title = {{{Distillation of squeezing using an engineered pulsed parametric down-conversion source}}}, doi = {{10.1364/oe.402178}}, volume = {{28}}, year = {{2020}}, } @article{21025, author = {{Eigner, Christof and Padberg, Laura and Santandrea, Matteo and Herrmann, Harald and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{22}}, title = {{{Spatially single mode photon pair source at 800 nm in periodically poled Rubidium exchanged KTP waveguides}}}, doi = {{10.1364/oe.399483}}, volume = {{28}}, year = {{2020}}, } @article{25920, author = {{Padberg, Laura and Santandrea, Matteo and Rüsing, Michael and Brockmeier, Julian and Mackwitz, Peter and Berth, Gerhard and Zrenner, Artur and Eigner, Christof and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Characterisation of width-dependent diffusion dynamics in rubidium-exchanged KTP waveguides}}}, doi = {{10.1364/oe.397074}}, year = {{2020}}, } @article{47958, abstract = {{High-fidelity periodic poling over long lengths is required for robust, quasi-phase-matched second-harmonic generation using the fundamental, quasi-TE polarized waveguide modes in a thin-film lithium niobate (TFLN) waveguide. Here, a shallow-etched ridge waveguide is fabricated in x-cut magnesium oxide doped TFLN and is poled accurately over 5 mm. The high fidelity of the poling is demonstrated over long lengths using a non-destructive technique of confocal scanning second-harmonic microscopy. We report a second-harmonic conversion efficiency of up to 939 %/W (length-normalized conversion efficiency 3757 %/Wcm²), measured at telecommunications wavelengths. The device demonstrates a narrow spectral linewidth (1 nm) and can be tuned precisely with a tuning characteristic of 0.1 nm/°C, over at least 40 °C without measurable loss of efficiency.}}, author = {{Zhao, Jie and Rüsing, Michael and Javid, Usman A. and Ling, Jingwei and Li, Mingxiao and Lin, Qiang and Mookherjea, Shayan}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{13}}, publisher = {{Optica Publishing Group}}, title = {{{Shallow-etched thin-film lithium niobate waveguides for highly-efficient second-harmonic generation}}}, doi = {{10.1364/oe.395545}}, volume = {{28}}, year = {{2020}}, } @article{26237, author = {{Luo, Kai-Hong and Ansari, Vahid and Massaro, Marcello and Santandrea, Matteo and Eigner, Christof and Ricken, Raimund and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Counter-propagating photon pair generation in a nonlinear waveguide}}}, doi = {{10.1364/oe.378789}}, year = {{2019}}, } @article{26509, author = {{Tiedau, Johannes and Meyer-Scott, Evan and Nitsche, Thomas and Barkhofen, Sonja and Bartley, Tim J. and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{A high dynamic range optical detector for measuring single photons and bright light}}}, doi = {{10.1364/oe.27.000001}}, year = {{2019}}, } @article{9826, author = {{Tiedau, Johannes and Meyer-Scott, Evan and Nitsche, Thomas and Barkhofen, Sonja and Bartley, Tim and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{A high dynamic range optical detector for measuring single photons and bright light}}}, doi = {{10.1364/oe.27.000001}}, year = {{2019}}, } @article{11955, author = {{Li, Tianyou and Wei, Qunshuo and Reineke, Bernhard and Walter, Felicitas and Wang, Yongtian and Zentgraf, Thomas and Huang, Lingling}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{15}}, pages = {{21153--21162}}, title = {{{Reconfigurable metasurface hologram by utilizing addressable dynamic pixels}}}, doi = {{10.1364/oe.27.021153}}, volume = {{27}}, year = {{2019}}, } @article{10282, author = {{Lin, Zemeng and Huang, Lingling and Zhao, Ruizhe and Wei, Qunshuo and Zentgraf, Thomas and Wang, Yongtian and Li, Xiaowei}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{13}}, pages = {{18740--18750}}, title = {{{Dynamic control of mode modulation and spatial multiplexing using hybrid metasurfaces}}}, doi = {{10.1364/oe.27.018740}}, volume = {{27}}, year = {{2019}}, } @article{26052, author = {{Luo, Kai Hong and Ansari, Vahid and Massaro, Marcello and Santandrea, Matteo and Eigner, Christof and Ricken, Raimund and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Counter-propagating photon pair generation in a nonlinear waveguide}}}, doi = {{10.1364/oe.378789}}, year = {{2019}}, } @article{13900, author = {{Song, Xiaohong and Zuo, Ruixin and Yang, Shidong and Li, Pengcheng and Meier, Torsten and Yang, Weifeng}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{3}}, pages = {{2225--2234}}, title = {{{Attosecond temporal confinement of interband excitation by intraband motion}}}, doi = {{10.1364/oe.27.002225}}, volume = {{27}}, year = {{2019}}, } @article{47946, author = {{Zhao, Jie and Rüsing, Michael and Mookherjea, Shayan}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{9}}, publisher = {{The Optical Society}}, title = {{{Optical diagnostic methods for monitoring the poling of thin-film lithium niobate waveguides}}}, doi = {{10.1364/oe.27.012025}}, volume = {{27}}, year = {{2019}}, } @article{9614, author = {{Eigner, Christof and Santandrea, Matteo and Padberg, Laura and Volk, Martin F. and Rüter, Christian E. and Herrmann, Harald and Kip, Detlef and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Periodically poled ridge waveguides in KTP for second harmonic generation in the UV regime}}}, doi = {{10.1364/oe.26.028827}}, year = {{2018}}, } @article{9619, author = {{Ansari, V. and Roccia, E. and Santandrea, Matteo and Doostdar, M. and Eigner, Christof and Padberg, Laura and Gianani, I. and Sbroscia, M. and Donohue, J. M. and Mancino, L. and Barbieri, M. and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Heralded generation of high-purity ultrashort single photons in programmable temporal shapes}}}, doi = {{10.1364/oe.26.002764}}, year = {{2018}}, } @article{9638, author = {{Meyer-Scott, Evan and Prasannan, Nidhin and Eigner, Christof and Quiring, Viktor and Donohue, John M. and Barkhofen, Sonja and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{High-performance source of spectrally pure, polarization entangled photon pairs based on hybrid integrated-bulk optics}}}, doi = {{10.1364/oe.26.032475}}, year = {{2018}}, } @article{3832, abstract = {{Controlling light emission out of subwavelength nanoslit/aperture structures is of great important for highly integrated photonic circuits. Here we propose a new method to achieve direction-tunable emission based on a compact metallic microcavity with double nanoslit. Our method combines the principles of Young’s interference and surface plasmon polaritons interference. We show that the direction of the far-field beam can be controlled over a wide range of angles by manipulating the frequency and relative phase of light arriving at the two slits, which holds promise for applications in the ultracompact optoelectronic devices.}}, author = {{Song, Xiaohong and Wang, Nini and Yan, Ming and Lin, Cheng and Förstner, Jens and Yang, Weifeng}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_plasmonics}}, number = {{12}}, pages = {{13207--13214}}, publisher = {{The Optical Society}}, title = {{{Direction-tunable enhanced emission from a subwavelength metallic double-nanoslit structure}}}, doi = {{10.1364/oe.25.013207}}, volume = {{25}}, year = {{2017}}, } @article{681, author = {{Guo, Qinghua and Schlickriede, Christian and Wang, Dongyang and Liu, Hongchao and Xiang, Yuanjiang and Zentgraf, Thomas and Zhang, Shuang}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{13}}, publisher = {{The Optical Society}}, title = {{{Manipulation of vector beam polarization with geometric metasurfaces}}}, doi = {{10.1364/oe.25.014300}}, volume = {{25}}, year = {{2017}}, } @article{13353, author = {{Lewandowski, Przemyslaw and Luk, Samuel M. H. and Chan, Chris K. P. and Leung, P. T. and Kwong, N. H. and Binder, Rolf and Schumacher, Stefan}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{25}}, title = {{{Directional optical switching and transistor functionality using optical parametric oscillation in a spinor polariton fluid}}}, doi = {{10.1364/oe.25.031056}}, volume = {{25}}, year = {{2017}}, } @article{35873, author = {{Wahle, Markus and Brassat, Katharina and Ebel, Justus and Bürger, Julius and Lindner, Jörg K. N. and Kitzerow, Heinz-Siegfried}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{19}}, publisher = {{The Optical Society}}, title = {{{Two-dimensional switchable blue phase gratings manufactured by nanosphere lithography}}}, doi = {{10.1364/oe.25.022608}}, volume = {{25}}, year = {{2017}}, } @article{3434, abstract = {{In this work we study the impact of ion implantation on the nonlinear optical properties in MgO:LiNbO3 via confocal second-harmonic microscopy. In detail, we spatially characterize the nonlinear susceptibility in carbon-ion implanted lithium niobate planar waveguides for different implantation energies and fluences, as well as the effect of annealing. In a further step, a computational simulation is used to calculate the implantation range of carbon-ions and the corresponding defect density distribution. A comparison between the simulation and the experimental data indicates that the depth profile of the second-order effective nonlinear coefficient is directly connected to the defect density that is induced by the ion irradiation. Furthermore it can be demonstrated that the annealing treatment partially recovers the second-order optical susceptibility.}}, author = {{Spychala, Kai J. and Berth, Gerhard and Widhalm, Alex and Rüsing, Michael and Wang, Lei and Sanna, Simone and Zrenner, Artur}}, issn = {{1094-4087}}, journal = {{OPTICS EXPRESS}}, number = {{18}}, pages = {{21444----21453}}, title = {{{Impact of carbon-ion implantation on the nonlinear optical susceptibility of LiNbO3}}}, doi = {{10.1364/OE.25.021444}}, year = {{2017}}, } @article{3841, abstract = {{We present phase sensitive cavity field measurements on photonic crystal microcavities. The experiments have been performed as autocorrelation measurements with ps double pulse laser excitation for resonant and detuned conditions. Measured E-field autocorrelation functions reveal a very strong detuning dependence of the phase shift between laser and cavity field and of the autocorrelation amplitude of the cavity field. The fully resolved phase information allows for a precise frequency discrimination and hence for a precise measurement of the detuning between laser and cavity. The behavior of the autocorrelation amplitude and phase and their detuning dependence can be fully described by an analytic model. Furthermore, coherent control of the cavity field is demonstrated by tailored laser excitation with phase and amplitude controlled pulses. The experimental proof and verification of the above described phenomena became possible by an electric detection scheme, which employs planar photonic crystal microcavity photo diodes with metallic Schottky contacts in the defect region of the resonator. The applied photo current detection was shown to work also efficiently at room temperature, which make electrically contacted microcavities attractive for real world applications.}}, author = {{Quiring, Wadim and Jonas, Björn and Förstner, Jens and Rai, Ashish K. and Reuter, Dirk and Wieck, Andreas D. and Zrenner, Artur}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_phc}}, number = {{18}}, pages = {{20672--20684}}, publisher = {{The Optical Society}}, title = {{{Phase sensitive properties and coherent manipulation of a photonic crystal microcavity}}}, doi = {{10.1364/oe.24.020672}}, volume = {{24}}, year = {{2016}}, } @article{3884, abstract = {{e study the discrete soliton formation in one- and two- dimensional arrays of nanowires coated with graphene monolayers. Highly confined solitons, including the fundamental and the higher-order modes, are found to be supported by the proposed structure with a low level of power flow. Numerical analysis reveals that, by tuning the input intensity and Fermi energy, the beam diffraction, soliton dimension and propagation loss can be fully controlled in a broad range, indicating potential values of the graphene-based solitons in nonlinear/active nanophotonic systems. }}, author = {{Kou, Yao and Förstner, Jens}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_plasmonics, tet_topic_polariton}}, number = {{5}}, pages = {{4714}}, publisher = {{The Optical Society}}, title = {{{Discrete plasmonic solitons in graphene-coated nanowire arrays}}}, doi = {{10.1364/oe.24.004714}}, volume = {{24}}, year = {{2016}}, } @article{21035, author = {{Krapick, Stephan and Brecht, Benjamin and Herrmann, Harald and Quiring, Viktor and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{3}}, title = {{{On-chip generation of photon-triplet states}}}, doi = {{10.1364/oe.24.002836}}, volume = {{24}}, year = {{2016}}, } @article{6533, abstract = {{We propose and implement a new concept for thermochromic plasmonic elements. It is based on vanadium dioxide (VO2) nanocrystals located in the near field of surface plasmon polaritons supported by an otherwise unstructured gold thin film. When the VO2 undergoes the metal-insulator phase transition, the coupling conditions for conversion of light into propagating surface plasmon polaritons change markedly. In particular, we realize thermochromic plasmonic grating couplers with substantial switching contrast as well as tunable plasmonic couplers in a Kretschmann configuration. The use of VO2 nanocrystals permits highly repetitive switching and room temperature operation. Simulations based on the actual dielectric function of our VO2 nanocrystals agree well with the experiment.}}, author = {{Jostmeier, Thorben and Mangold, Moritz and Zimmer, Johannes and Karl, Helmut and Krenner, Hubert J. and Ruppert, Claudia and Betz, Markus}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{15}}, publisher = {{The Optical Society}}, title = {{{Thermochromic modulation of surface plasmon polaritons in vanadium dioxide nanocomposites}}}, doi = {{10.1364/oe.24.017321}}, volume = {{24}}, year = {{2016}}, }