Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Conference on Lasers and Electro-Optics

All-optical recognition of spectrally coded optical pulses using periodically poled lithium niobate second-harmonic waveguides for ultrashort pulse optical code division multiple-access

Zheng Zheng, Andrew M. Weiner, Krishnan R. Parameswaran, Ming-Han Chou, M. M. Fejer

Published Jan 1, 2000• 1 citation
Publisher

Abstract

Summary form only given.There been increasing interest in realizing optical signal processing functions in optical communication systems based on nonlinear optical parametric processes. In the proposed ultrashort pulse optical code-division multiple access (CDMA) systems, in order to realize multiplexing and demultiplexing for multichannel operation, a nonlinear element is needed to distinguish between correctly decoded signals and incorrectly decoded multiaccess interference, which have comparable average optical power but carry different spectral information. It had been proposed to realize all-optical recognition of optical phase-coded ultrashort waveforms by using second-harmonic generation in long nonlinear crystals, which could have advantages in contrast ratio, operating power and detection efficiency over other proposed schemes. While high contrast ratios have been demonstrated based on such a scheme using bulk periodically poled lithium niobate (PPLN) crystals, the high efficiency has not yet been demonstrated. We use a simple combination of PPLN SHG waveguides and conventional photodetectors to realize all-optical recognition of spectrally phase coded optical pulses, which shows the potential of much higher conversion efficiency compared to previous bulk experiments, which is crucial for real-time operation with a high signal to noise ratio.

DOI
10.1109/cleo.2000.906901

Related papers

Novel optical thresholder based on second harmonic generation in long periodically poled lithium niobate for ultrashort pulse optical code division multiple-access

Zheng Zheng, Andrew M. Weiner

We report a novel yet practical optical thresholding scheme for ultrashort pulse CDMA using second harmonic generation in a long PPLN crystal, with a demonstrated contrast ratio of /spl sim/30 dB and the potential for low power operation.

Optical Fiber Communication Conference•Nov 7, 2002•0 citations

Spectral phase correlation of coded femtosecond pulses by second-harmonic generation in thick nonlinear crystals

Zheng Zheng, Andrew M. Weiner

We demonstrate a novel all-optical scheme for measuring the correlation of spectrally phase-coded ultrashort optical waveforms that uses second-harmonic generation (SHG) in long, periodically poled lithium niobate crystals. The SHG yield can be controlled over a range of ~30 dB, depending on the correlation of the applied phase codes. Such a spectral phase correlator has applications for ultrashort-pulse optical code-division multiple-access networking and could serve as a nonlinear optical but classical analog for certain schemes for coherent quantum control of multiphoton processes.

Optics Letters•Jul 1, 2000•57 citations

Nonlinear optical components and systems for quantum technologies and communications

Alan C. Gray

This thesis describes a series of experimental research primarily revolving around the applications of periodically poled lithium niobate (PPLN). Initially, a set of work is described regarding the fabrication and characterisation of PPLN ridge waveguides designed for frequency doubling into the blue/UV range. These waveguides are fabricated via diffusion of zinc into the crystal structure. A precision dicing process creates the sidewall definition for modal confinement and also optical facet preparation. Preliminary results with the most efficient waveguide fabricated produced a maximum conversion efficiency of 6.9%/W in a 14 mm-long device, generating 391 nm light. This was performed with a novel near-IR VECSEL; designed and built as part of a collaboration with the research undertaken in this thesis to investigate new routes for miniaturised UV sources. The development of a non-destructive route to characterise the physical dimensions of a ridge waveguide for nonlinear applications is also presented. This presented methodology uses white light interferometry and standard edge recognition algorithms to determine the waveguide width profile. In combination with numerical propagation constant data for these waveguides, a numerical phasematching spectra can be calculated. A comparison to the experimental phasematching spectra of the second-harmonic generation process enables the discrimination between issues in the fabrication processes. Using bulk PPLN, a final application is presented for communications using mid-IR radiation and all commercial components. This configuration involves the use of differencefrequency generation followed by sum-frequency generation to create the transmitter and receiver systems, respectively. This enables final detection of 809 nm light (firmly within the silicon absorption band). Bit error ratios as low as 10−7 from single-pass nonlinear conversion for both systems without the need for an additional optical amplifier in the receiver. Finally, the propagation of relative intensity noise within the system as the source lasers propagate through a two step nonlinear conversion is presented and discussed within.

•Mar 1, 2021•0 citations

Broadband Quantum Photon Source in Step-Chirped Periodically Poled Lithium Niobate Waveguide

Xiao‐Xu Fang, Guo-Liang Shentu, Lu He

Broadband nonlinear optical devices play a critical role in both classical and quantum optics. Here, we design and fabricate a 6.82-mm-long step-chirped periodically poled lithium niobate~(CPPLN) waveguide on lithium niobate on insulator, which enables quasi-phase matching over a broad bandwidth for second-harmonic generation~(SHG) and spontaneous parametric down-conversion~(SPDC). The SHG achieves an average efficiency of 54.4\%/W/cm$^2$ over the first-harmonic wavelength range of 1510~nm-1620~nm, paving the way for realizing SPDC across a wide range of pump wavelengths. For SPDC, by tuning the pump wavelength to 775~nm, 780~nm, and 785~nm, we achieve broadband photon-pair generation with a maximum full bandwidth and brightness up to 99~THz~(846~nm) and 20~GHz/mW/nm, respectively. Our findings provide an efficient and experiment-friendly approach for generating broadband photon pairs, which holds significant promise for advancing applications in quantum metrology.

arXiv:2510.03619•Oct 4, 2025•0 citations

Parametric phase-sensitive and phase-insensitive all-opt ical signal processing on multiple nonlinear platforms

Christophe Peucheret, Francesco Da Ros, Vukovic, Dragana +13 more

Parametric processes in materials presenting a second- or third-order nonlinearity have been widely used to demonstrate a wide range of all-optical signal processing functionalities, including amplification, wavelength conversion, regeneration, sampling, switching, modulation format conversion, optical phase conjugation, etc.. The recent evolution of optical fiber communication systems towards advanced modulation formats making use of the phase dimension, as well as polarization and, more recently, space-multiplexing, has created new requirements, as well as new opportunities, for parametric all-optical signal processing. In this presentation, we will review our recent results on the demonstration of all-optical parametric signal processing using different nonlinear platforms, including highly nonlinear optical fibers (HNLFs), silicon nanowires, and periodically-poled lithium niobate (PPLN) waveguides. In particular, we will show how phase-sensitive processes can be engineered to demonstrate phase-quadrature separation, which we have recently demonstrated in HNLFs and PPLN waveguides. Silicon nanowires are particularly attractive for signal processing thanks to their compact size, CMOS compatible fabrication process, degrees of freedom in dispersion engineering, and high nonlinear coefficient. However, the detrimental effect of free-carrier absorption induced by two-photon absorption has so far prevented them from being used for the demonstration of phase-sensitive processing. Thanks to the introduction of p-i-n junctions across silicon waveguides, we have recently been able to demonstrate phase-sensitive extinction ratios as high as 20 dB, allowing the phase regeneration of phase-modulated signals under continuous wave pumping operation. One of the well-known limitations of planar waveguide devices for all-optical signal processing is their inherent polarization sensitivity. We will show how the introduction of polarization-diversity circuits relying on efficient and wideband polarization splitters and rotators can overcome this limitation. Finally, we will also discuss the introduction of signal processing functionalities that are compatible with the novel dimension of space multiplexing. More specifically, we will show how mode-selective wavelength conversion based on four-wave mixing can be realized in a multimode silicon waveguide.

•Aug 25, 2014•0 citations

Broadband quantum photon source in a step-chirped periodically poled lithium niobate waveguide

Xiao‐Xu Fang, Guoliang Shentu, he lu

Broadband nonlinear optical devices play a critical role in both classical and quantum optics. Here, we design and fabricate a 6.82-mm-long step-chirped periodically poled lithium niobate (CPPLN) waveguide on lithium niobate on insulator, which enables quasi-phase matching over a broad bandwidth for second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC). The SHG achieves an average efficiency of 91%/W/cm 2 over the first-harmonic wavelength range of 1510 nm–1620 nm, paving the way for realizing SPDC across a wide range of pump wavelengths. For SPDC, by tuning the pump wavelength to 775 nm, 780 nm, and 785 nm, we achieve broadband photon-pair generation with a maximum full bandwidth and brightness up to 99 THz (846 nm) and 21 MHz/mW/nm, respectively. Our findings provide an efficient and experiment-friendly approach for generating broadband photon pairs, which holds significant promise for advancing applications in quantum metrology.

Optics Express•Jan 13, 2026•2 citations
Summary form only given.There been increasing interest in realizing optical signal processing functions in optical communication systems based on nonlinear optical parametric processes. In the proposed ultrashort pulse optical code-division multiple access (CDMA) systems, in order to realize multiplexing and demultiplexing for multichannel operation, a nonlinear element is needed to distinguish between correctly decoded signals and incorrectly decoded multiaccess interference, which have comparable average optical power but carry different spectral information. It had been proposed to realize all-optical recognition of optical phase-coded ultrashort waveforms by using second-harmonic generation in long nonlinear crystals, which could have advantages in contrast ratio, operating power and detection efficiency over other proposed schemes. While high contrast ratios have been demonstrated based on such a scheme using bulk periodically poled lithium niobate (PPLN) crystals, the high efficiency has not yet been demonstrated. We use a simple combination of PPLN SHG waveguides and conventional photodetectors to realize all-optical recognition of spectrally phase coded optical pulses, which shows the potential of much higher conversion efficiency compared to previous bulk experiments, which is crucial for real-time operation with a high signal to noise ratio.
We demonstrate a novel all-optical scheme for measuring the correlation of spectrally phase-coded ultrashort optical waveforms that uses second-harmonic generation (SHG) in long, periodically poled lithium niobate crystals. The SHG yield can be controlled over a range of ~30 dB, depending on the correlation of the applied phase codes. Such a spectral phase correlator has applications for ultrashort-pulse optical code-division multiple-access networking and could serve as a nonlinear optical but classical analog for certain schemes for coherent quantum control of multiphoton processes.
This thesis describes a series of experimental research primarily revolving around the applications of periodically poled lithium niobate (PPLN). Initially, a set of work is described regarding the fabrication and characterisation of PPLN ridge waveguides designed for frequency doubling into the blue/UV range. These waveguides are fabricated via diffusion of zinc into the crystal structure. A precision dicing process creates the sidewall definition for modal confinement and also optical facet preparation. Preliminary results with the most efficient waveguide fabricated produced a maximum conversion efficiency of 6.9%/W in a 14 mm-long device, generating 391 nm light. This was performed with a novel near-IR VECSEL; designed and built as part of a collaboration with the research undertaken in this thesis to investigate new routes for miniaturised UV sources. The development of a non-destructive route to characterise the physical dimensions of a ridge waveguide for nonlinear applications is also presented. This presented methodology uses white light interferometry and standard edge recognition algorithms to determine the waveguide width profile. In combination with numerical propagation constant data for these waveguides, a numerical phasematching spectra can be calculated. A comparison to the experimental phasematching spectra of the second-harmonic generation process enables the discrimination between issues in the fabrication processes. Using bulk PPLN, a final application is presented for communications using mid-IR radiation and all commercial components. This configuration involves the use of differencefrequency generation followed by sum-frequency generation to create the transmitter and receiver systems, respectively. This enables final detection of 809 nm light (firmly within the silicon absorption band). Bit error ratios as low as 10−7 from single-pass nonlinear conversion for both systems without the need for an additional optical amplifier in the receiver. Finally, the propagation of relative intensity noise within the system as the source lasers propagate through a two step nonlinear conversion is presented and discussed within.
Broadband nonlinear optical devices play a critical role in both classical and quantum optics. Here, we design and fabricate a 6.82-mm-long step-chirped periodically poled lithium niobate~(CPPLN) waveguide on lithium niobate on insulator, which enables quasi-phase matching over a broad bandwidth for second-harmonic generation~(SHG) and spontaneous parametric down-conversion~(SPDC). The SHG achieves an average efficiency of 54.4\%/W/cm2^22 over the first-harmonic wavelength range of 1510~nm-1620~nm, paving the way for realizing SPDC across a wide range of pump wavelengths. For SPDC, by tuning the pump wavelength to 775~nm, 780~nm, and 785~nm, we achieve broadband photon-pair generation with a maximum full bandwidth and brightness up to 99~THz~(846~nm) and 20~GHz/mW/nm, respectively. Our findings provide an efficient and experiment-friendly approach for generating broadband photon pairs, which holds significant promise for advancing applications in quantum metrology.
Parametric processes in materials presenting a second- or third-order nonlinearity have been widely used to demonstrate a wide range of all-optical signal processing functionalities, including amplification, wavelength conversion, regeneration, sampling, switching, modulation format conversion, optical phase conjugation, etc.. The recent evolution of optical fiber communication systems towards advanced modulation formats making use of the phase dimension, as well as polarization and, more recently, space-multiplexing, has created new requirements, as well as new opportunities, for parametric all-optical signal processing. In this presentation, we will review our recent results on the demonstration of all-optical parametric signal processing using different nonlinear platforms, including highly nonlinear optical fibers (HNLFs), silicon nanowires, and periodically-poled lithium niobate (PPLN) waveguides. In particular, we will show how phase-sensitive processes can be engineered to demonstrate phase-quadrature separation, which we have recently demonstrated in HNLFs and PPLN waveguides. Silicon nanowires are particularly attractive for signal processing thanks to their compact size, CMOS compatible fabrication process, degrees of freedom in dispersion engineering, and high nonlinear coefficient. However, the detrimental effect of free-carrier absorption induced by two-photon absorption has so far prevented them from being used for the demonstration of phase-sensitive processing. Thanks to the introduction of p-i-n junctions across silicon waveguides, we have recently been able to demonstrate phase-sensitive extinction ratios as high as 20 dB, allowing the phase regeneration of phase-modulated signals under continuous wave pumping operation. One of the well-known limitations of planar waveguide devices for all-optical signal processing is their inherent polarization sensitivity. We will show how the introduction of polarization-diversity circuits relying on efficient and wideband polarization splitters and rotators can overcome this limitation. Finally, we will also discuss the introduction of signal processing functionalities that are compatible with the novel dimension of space multiplexing. More specifically, we will show how mode-selective wavelength conversion based on four-wave mixing can be realized in a multimode silicon waveguide.
Broadband nonlinear optical devices play a critical role in both classical and quantum optics. Here, we design and fabricate a 6.82-mm-long step-chirped periodically poled lithium niobate (CPPLN) waveguide on lithium niobate on insulator, which enables quasi-phase matching over a broad bandwidth for second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC). The SHG achieves an average efficiency of 91%/W/cm 2 over the first-harmonic wavelength range of 1510 nm–1620 nm, paving the way for realizing SPDC across a wide range of pump wavelengths. For SPDC, by tuning the pump wavelength to 775 nm, 780 nm, and 785 nm, we achieve broadband photon-pair generation with a maximum full bandwidth and brightness up to 99 THz (846 nm) and 21 MHz/mW/nm, respectively. Our findings provide an efficient and experiment-friendly approach for generating broadband photon pairs, which holds significant promise for advancing applications in quantum metrology.