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en: Terahertz wireless communication in a 560-GHz band using a Kerr micro-resonator soliton comb

en: Optics Continuum

ja: Optics Continuum


en: Effect of shift in refractive index of dispersive elements in waveband-shift-free optical phase conjugator based on DFG

en: Optical Review

ja: Optical Review


en: Waveband-shift-free optical phase conjugator based on difference-frequency generation

en: In this paper, a waveband-shift-free optical phase conjugator based on difference-frequency generation (DFG-OPC) that enables broadband operation is proposed and theoretically investigated. First, the principle of phase-conjugated (PC) wave generation with the DFG-OPC is mathematically described. Using a Sagnac loop interferometer with a χ optical nonlinear material and two dispersive elements (DEs), a PC wave with the same wavelength as a signal can be generated. Subsequently, the required DE length difference for the PC wave generation is theoretically calculated. The calculation results indicate the minimal DE length difference is 20.0 μm, and this is because the DFG-OPC enables broadband operation. Second, the wavelength characteristics of the DFG-OPC are investigated through numerical simulation. The operation bandwidth of the DFG-OPC depends on the DE length difference, and an operating bandwidth of the DFG-OPC of 54.5 nm can be achieved when the DE length difference is less than 0.01 m. Finally, the influence of the splitting ratio of an optical 3-dB coupler in the DFG-OPC is numerically studied. The results indicate that tolerance of the optical coupler splitting ratio is equal to or less than ±6% for the DFG-OPC.

en: Optics Express

ja: Optics Express


en: PPLN-based Low-noise Phase Sensitive Amplification Using an Optical Phase-locked Pump

en: IEICE Transactions on Communications

ja: IEICE Transactions on Communications


en: Simultaneous carrier extraction from wavelength-division-multiplexed phase-conjugated twin waves by using sum-frequency generation with second-order optical nonlinear medium for phase-sensitive optical amplifier repeaters

en: Japanese Journal of Applied Physics, Part 1 (Special Issues)


en: Optical QPSK Signal Quality Degradation due to Phase Error of Pump Light in Optical Parametric Phase-Sensitive Amplifier Repeaters


en: Polarization Dependence of Carrier Extraction from Dual-Polarization Phase-Conjugated Twin Waves with Sum-Frequency Generation

en: The Review of Laser Engineering

ja: The Review of Laser Engineering


en: Optical pump phase locking to a carrier wave extracted from phase-conjugated twin waves for phase-sensitive optical amplifier repeaters

en: In this paper, an optical phase-locked loop assisted by sum-frequency and second-harmonic generation (SS-OPLL) for frequency nondegenerate optical parametric phase-sensitive amplifier repeaters is experimentally demonstrated. First, theoretical derivations show that carrier extraction from phase-conjugated twin waves (PCTWs) and reference light generation are achieved by sum-frequency generation; therefore, the SS-OPLL circuit enables optical phase locking between PCTWs and a pump wave by a simple architecture based on a balanced OPLL. Then, optical phase locking between 20-Gbit/s quadrature phase-shift keying PCTWs and an individual pump source is experimentally demonstrated. Experimental results indicate that phase errors were reduced during the SS-OPLL operation.


en: Simultaneous detection of 10-Gbit/s QPSK x 2-ch. Fourier-encoded synchronous OCDM signals with digital coherent receiver

en: We experimentally demonstrate the simultaneous detection of 10-Gbit/s quadrature phase shift keying (QPSK) × 2-channel Fourier-encoded synchronous optical code division multiplexing (FE-SOCDM) signals using a digital coherent receiver, for the first time. First, we analytically verify that simultaneous detection can be achieved with an N-point discrete Fourier transform (DFT) using digital signal processing (DSP) because the N-channel Fourier encoding corresponds to an N × N inverse DFT, then the operation is experimentally confirmed. Simultaneous detection of 10-Gbit/s QPSK × 2-channel FE-SOCDM signals is evaluated. The proposed scheme dramatically expands the capability of OCDM systems.


en: ディジタルコヒーレント受信機におけるイントラダイン方式の適用可能性の検討

ja: ディジタルコヒーレント受信機におけるイントラダイン方式の適用可能性の検討

ja: レーザー研究


en: Amplitude Noise Suppression of BPSK Signals Using Transmission Optical Fibers and Optical Parametric Phase-Sensitive Amplifiers

en: IEICE Electronics Express

ja: IEICE Electronics Express


en: Dispersion compensation of wavelength-division multiplexed signals using waveband shift-free optical phase conjugators

en: IEICE Communications Express

ja: IEICE Communications Express


en: Pump phase-locking to fiber-transmitted QPSK phase-conjugated twin waves for non-degenerate phase-sensitive amplifier repeaters


en: First demonstration of phase-sensitive gain stabilization by using heterodyne Costas optical phase-locked loop


en: All Optical Generation of Optical BPSK/QPSK Signals Interleaved with Reference Light

en: IEEE Photonics Technology Letters

ja: IEEE Photonics Technology Letters