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


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

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.


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


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

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


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


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


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

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.


Phase-Noise Characteristics of a 25-GHz-Spaced Optical Frequency Comb Based on a Phase- and Intensity-Modulated Laser

We investigated phase-noise characteristics of both a phase/intensity-modulated laser with 25-GHz mode spacing and a mode-locked fiber laser with carrier-envelope-offset (CEO) locking. As the separation from the frequency of the continuous wave (CW) laser diode (LD) for a seed light source increases, the integrated phase noise of each comb mode of both the phase/intensity-modulated laser and supercontinuum light originating from it increases with the same slope as a function of mode number. The dependence of the integrated phase noise on mode number with the phase/intensity-modulated laser is much larger than with the mode-locked fiber laser of the CEO locking. However, the phase noise of the phase/intensity-modulated laser is extremely lower than that of the mode-locked fiber laser with CEO locking in the frequency region around the CW LD. The phase noise of the phase/intensity-modulated laser with 25-GHz mode spacing and that of the mode-locked fiber laser with the CEO locking could be estimated and were found to be almost the same at the wavelengths required in an f-to-2f self-referencing interferometer. Our experimental results indicate the possibility of achieving an offset-frequency-locked frequency comb with the phase/intensity-modulated laser.


Security in Photonic Networks: Threats and Security Enhancement

IEEE/OSA Journal of Lightwave Technology


Generation of 120-fs laser pulses at 1-GHz repetition rate derived from continuous wave laser diode

We report the first demonstration of continuous-wave laser diode based 100-fs-class pulse lasers operating at a gigahertz repetition rate without a mode-locking technique. We describe the performance of a 1-W, 120-fs optical pulse train at 1 GHz and a 1-W, 80-fs optical pulse train at 250 MHz by using a simple configuration. Sub-100-fs pulse durations are achieved by using a progressive expansion of the spectrum in the self-phase modulation process in an erbium-doped fibre amplifier. Our scheme can achieve continuously tunable repetition rate in the range of ± 20%, and develop powerful tools for use in nanomechanical systems and nanobiotechnology.


Phase sensitive degenerate parametric amplification using directly-bonded PPLN ridge waveguides

We constructed the first CW pumped degenerate parametric amplifier based on periodically poled and ZnO-doped LiNbO3 ridge waveguides. An in-phase gain of + 11 dB was achieved owing to the high conversion efficiency and high damage resistance of the waveguide obtained by employing direct bonding and dry etching techniques. Nearly identical amplification and deamplification were obtained owing to a sufficient spatial and temporal overlap between the pump and signal beams. No secondary wavelength conversion process was observed, and a maximum output of 22 dBm was obtained. We also successfully demonstrated the phase sensitive amplification of a modulated signal light.


Digital compensation of intercarrier nonlinear distortion with carrier phase locking


Influence of intra-channel crosstalk with frequency dependence on signal degradation in optical switch network


Multicarrier light source with flattened spectrum using phase modulators and dispersion medium


Achievement of Subchannel Frequency Spacing Less Than Symbol Rate and Improvement of Dispersion Tolerance in Optical OFDM Transmission


Congestion-controlled optical burst switching network with connection guarantee: design and demonstration


Noise figure of parametric wavelength conversion with quasi-phase-matched LiNbO3 waveguide

IEEE Journal of Selected Topics in Quantum Electronics


Field demonstration of up to 640 Gb/s (64 ch x 10 Gb/s) GWP switching networks with a QPM-LN wavelength converter in JGN II test bed


Low-crosstalk 103 channel x 10 Gb/s (1.03 Tb/s) wavelength conversion with a quasi-phase-matched LiNbO3 waveguide


Evaluation of amount of equipment on single-layer optical path networks managing multigranularity optical paths


Noise figure of phase-sensitive parametric amplifier using a Mach-Zehnder interferometer with lossy Kerr media and noisy pump


Architecture of ultrafast optical packet switching ring network

IEEE/OSA Journal of Lightwave Technology


Gain characteristics of coherent optical amplifiers using a Mach-Zehnder interferometer with Kerr media


High-frequency synchronized signal generation using semiconductor lasers

IEEE Transactions on Microwave Theory and Techniques


In-line optical phase-sensitive amplifier with pump light source controlled by optical phase-lock loop


Theoretical analysis of system limitation for AM-DD/NRZ optical transmission systems using in-line phase-sensitive amplifiers


Modeling the gain degradation of high concentration erbium-doped fiber amplifiers by introducing inhomogeneous cooperative up-conversion


1.8 Gbit/s transmission over 210 km using an Erbium-doped fiber laser amplifier with 20 dB repeater gain in a direct detection system


Wide-band frequency-response measurement of optical receivers using optical heterodyne detection


High-speed picosecond optical pulse compression from gain-switched 1.3 μm distributed feedback-laser diode (DFB-LD) through highly dispersive single-mode fiber


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


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


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


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


Octave-spanning frequency comb generated by 250 fs pulse train emitted from 25 GHz externally phase-modulated laser diode for carrier-envelope-offset-locking


Flexible chromatic dispersion compensation over entire L-band for over 40-Gb/s WDM transparent networks using multichannel tunable optical dispersion compensator


Laser diode optical frequency stabilization technique on ITU-T frequency grid employing modulated sideband light


Low crosstalk and variable wavelength conversion using multiple QPM LiNbO3 waveguide module


Electro-optically multiplexed 110 Gbit/s optical OFDM signal transmission over 80 km SMF without dispersion compensation


Spectrally flattened phase-locked multi-carrier light generator with phase modulators and chirped fibre Bragg grating


Performance of nonlinear interchannel crosstalk pre-compensation at zero-dispersion wavelength using carrier phase-locked WDM


Compensation of interchannel crosstalk induced by optical fiber nonlinearity in carrier phase-locked WDM System


Polarisation-insensitive parametric wavelength conversion without tunable filters for converted light extraction


Repetition rate variable optical pulse generation using an optical frequency shifter


Field trial of virtual-grouped-wavelength-path switching with QPM-LN waveband converter and PLC matrix switch in JGN II test bed


On-grid wavelength conversion and multi-carrier generation with quasi-phase-matched LiNbO3 waveguide optical loop circuit


Widely tunable multichannel wavelength conversion using multiple wavelength quasi-phase-matched LiNbO3 waveguide


Simultaneous 25 GHz-spaced DWDM wavelength conversion of 1.03 Tbit/s (103 x 10 Gbit/s) signals in PPLN waveguide


Micromechanically controlled GT interferometer for optical-pulse narrowing


Inline coherent optical amplifier with noise figure lower than 3dB quantum limit


Low-noise amplification under the 3 dB noise figure in high-gain phase-sensitive fibre amplifier


Micromechanically controlled GT interferometer for ultrashort optical-pulse narrowing


Synchronization of subterahertz optical pulse train from PLL-controlled colliding pulse modelocked semiconductor laser


In-line optical phase-sensitive amplifier employing pump laser injection-locked to input signal light


Supermode selection of a subterahertz-harmonic colliding-pulse mode-locked semiconductor laser using continuous-wave light injection


In-line phase-sensitive amplifier with optical-PLL-controlled internal pump light source


A harmonic colliding-pulse mode-locked semiconductor laser for stable subterahertz pulse generation


Linewidth narrowing and optical phase control of mode-locked semiconductor ring laser employing optical injection locking


Optical phase-sensitive amplification using two phase-locked light sources


Reduction of fiber-nonlinearity-enhanced amplifier noise by means of phase-sensitive amplifiers


Repetition-rate tunable micromechanical passively mode-locked semiconductor laser


Synchronized pulse-train generation from passively mode-locked semiconductor lasers by a phase-locked loop using optical modulation sidebands


Amplitude noise suppression using a high gain phase sensitive amplifier as a limiting amplifier


Monolithic strained-InGaAsP multiple-quantum-well lasers with integrated electroabsorption modulators for active mode locking


Pulse width tunable subpicosecond pulse generation from an actively modelocked monolithic MQW laser / MQW electroabsorption modulator


A highly efficient two-stage Er3+-doped optical fiber amplifier employing an optical gate to effectively reduce ASE


High gain two-stage amplification with Erbium-doped fibre amplifier


Picosecond laser diode pulse amplification up to 12 W by laser diode pumped Erbium-doped fiber


30 GHz picosecond pulse generation from actively mode-locked erbium-doped fibre laser


Picosecond optical pulse generation from mode-locked phased laser diode array


3 GHz optical soliton propagation using all laser diodes


250 km Nonrepeated transmission experiment at 1.8 Gb/s using LD pumped Er3+-doped fibre amplifiers in IM/direct detection system


Mutual signal gain saturation in Er3+-doped fibre amplifier around 1.54 μm wavelength


Optical soliton propagation using 3 GHz gain-switched 1.3 ?m laser diodes


100 Gbit/s optical signal generation by time-division multiplication of modulated and compressed pulses from gain-switched distributed feedback (DFB) laser diode


Effective technique for measuring intrinsic bandwidths of DFB-LDs utilizing a satellite mode induced by far-end reflection


Ultrafast optical multi/demultiplexer utilising optical Kerr effect in polarization-maintaining single-mode fibres


Transform-limited 5.6ps optical pulse generation at 12 GHz repetition rate from gain-switched distributed feedback laser diode by employing pulse compression technique


Picosecond optical pulse compression from gain-switched 1.3 μm distributed-feedback laser diode through highly dispersive single-mode fibre