Yang Jing Wen

High-speed WDM-PON using CW injection-locked Fabry-Pérot laser diodes

We propose a new WDM-PON architecture using Fabry-Pérot laser diodes (FP-LDs) that are injection-locked by continuous wave (CW) seed light. The modulation characteristics of the CW light injection-locked FP-LD are first investigated. Both uplink and downlink transmissions at 10 Gb/s are experimentally demonstrated using the proposed CW injection-locked FP-LDs. It is shown that up to 16 laser cavity modes can be selectively injection-locked with side mode suppression ratio larger than 30dB. The effects of the location of FP-LD cavity modes, transmission distance, and injection wavelength detuning on the overall transmission performance are investigated. The possibility of eliminating polarization dependence of the proposed CW injection scheme is also experimentally demonstrated by properly configuring a depolarizer. The deployment cost for the proposed WDM PON is potentially low from the fact that the CW laser sources located at the central office can be shared by many WDM-PONs and low-cost FP-LDs are used as light sources for data rates as high as 10 Gb/s.

Photonic microwave phase shifter/modulator based on a nonlinear optical loop mirror incorporating a Mach-Zehnder interferometer

We realize a novel photonic microwave phase shifter/modulator based on a nonlinear optical loop mirror incorporating a Mach-Zehnder interferometer. A near-linear phase shifter exceeding 180 degrees and a phase modulation with 2.5 Gbit/s baseband signal are obtained for a 10 GHz microwave signal by this proposed device.

WDM-PON Architectures With a Single Shared Interferometric Filter for Carrier-Reuse Upstream Transmission

We propose two novel wavelength-division-multiplexed passive-optical-network (WDM-PON) architectures where subcarriers are employed to transmit downstream data and optical carriers are reused for upstream transmission. Architecture I is designed for the situation where two short distribution fibers are available between the remote node (RN) and each optical network unit (ONU), whereas Architecture II is devised for the case where there is only one distribution fiber between the RN and each ONU. Both architectures use only one interferometric filter located at the RN to simultaneously separate all downlink optical carriers and subcarriers, leading to a considerable cost reduction in the implementation of the WDM-PONs. Separated optical carriers are then reused and injected into reflective semiconductor optical amplifiers as the uplink light sources, which eliminates the necessity of specific wavelength sources at the ONUs. The downstream subcarrier signals are directly detected using baseband receivers. Two multichannel upstream and downstream transmission experiments are carried out at 1.25 Gb/s using the proposed schemes. The impact of optical carrier-to-subcarrier ratio of downlink signal, Rayleigh-backscattering noise, and wavelength mismatch between laser source and filter on system performance is also investigated.

EDFA transient control based on envelope detection for optical burst switched networks

We propose and demonstrate a simple technique to control rapid erbium-doped fiber amplifier (EDFA) transients in optical burst switched networks. We demonstrate a 6-dB transient reduction in a 10-Gb/s 80-km-long wavelength-division-multiplexing system with three EDFAs. We show through simulation that the technique can be used at the first EDFA in links of as many as ten EDFAs to control transients to within 2 dB.

Optimization of Spectrum-Sliced ASE Source for Injection-Locking a Fabry–PÉrot Laser Diode

We experimentally study the impact of filter bandwidth of a spectrum-sliced amplified spontaneous emission (ASE) source on the injection-locking of a Fabry-Perot laser diode (FPLD) for passive optical network application. Optimal bandwidth of a spectrum-sliced ASE source was found in terms of receiver sensitivity after transmission. We also investigate the impact of intensity noise (IN) of the spectrum-sliced ASE source and its suppression for a wavelength-locked FPLD using a semiconductor optical amplifier. Experiment results show that the output performance of a wavelength-locked FPLD is improved by IN suppression

RZ/CSRZ-DPSK and chirped NRZ signal generation using a single-stage dual-electrode Mach-Zehnder modulator

This letter presents a novel configuration for return-to-zero (RZ) differential phase-shift keyed (DPSK), carrier-suppressed (CS) RZ DPSK, and chirped nonreturn-to-zero (CNRZ) signal generation, which only requires a single-stage dual-electrode Mach-Zehnder modulator (DE-MZM). RZ-DPSK, CSRZ-DPSK, or CNRZ signals can be generated via the same configuration by changing the DE-MZM operating conditions. Analytical derivation and simulation on signal generation and wavelength-division-multiplexed transmission was also carried out to justify the equivalence of the proposed scheme and conventional methods. The proposed scheme is expected to be more cost-effective due to the reduction in required modulator number.

Externally Modulated Optical Minimum Shift Keying Format

This paper presents the generation and the performance evaluation of optical minimum shift keying (MSK) for high-speed and high-spectral-efficiency wavelength-division multiplexing systems. The detailed principle on optical MSK generation and detection is derived and analyzed. Optical MSK data (10.7 Gb/s) are successfully generated by an experiment using the proposed scheme. The results show that the optical MSK signal exhibits a very compact optical spectrum. The performance of the optical MSK modulated system is evaluated and compared with those of 50% duty-cycle return-to-zero differential phase shift keying (RZ-DPSK) and 50% duty-cycle return-to-zero on-off keying (RZ-OOK) modulated systems, via both simulation and experiment, in terms of dispersion tolerance, linear crosstalk, self-phase modulation (SPM) tolerance, stimulated Brillouin scattering (SBS) threshold, optimal receiver filter bandwidth, and optimal link launch power into single-mode fibers and dispersion compensation fibers. Experimental and simulation results show that the MSK signal exhibits the largest tolerance against fiber dispersion and SPM effect as compared with RZ-DPSK and RZ-OOK. Experimental results also confirm the negative penalty against the SPM effect. The SBS threshold of both the MSK and RZ-DPSK systems is more than 10 dB higher than that of the RZ-OOK system. The MSK that is generated with conventional carrier-suppressed return-to-zero (CSRZ) pulses exhibits a narrower optimal optical filter bandwidth but a wider electrical filter bandwidth compared with those of RZ-OOK and RZ-DPSK. The MSK signal that is generated with pure dual-mode pulses has a similar optimum range to RZ-OOK and RZ-DPSK at a high optical signal-to-noise ratio (OSNR) but has a narrower optimal optical filter bandwidth at a low OSNR. The optimum fiber launch power study shows that the MSK signal that is generated using the conventional CSRZ pulses exhibits higher optimum launch power, which agrees with the SPM tolerance study.

Optical clock recovery at line rates via injection locking of a long cavity Fabry-Pe/spl acute/rot laser diode

We present a new scheme for realizing optical clock recovery by injection locking a long cavity Fabry-Pe/spl acute/rot laser diode. A 32.48-GHz optical clock with low level of timing jitter (0.38 ps) and high extinction ratio (23 dB) was recovered from a 32.48-Gb/s return-to-zero input optical data stream. The impact of the characteristics of the input signal such as the injected optical power and tunability of data rate on the measured radio-frequency power, timing jitter, and extinction ratio of the recovered clock signal has also been investigated.

PMD and chirp effects suppression in RF tone-based chromatic dispersion monitoring

We investigate the effects of polarization-mode dispersion (PMD) and chirp on radio-frequency tone-based chromatic dispersion (CD) monitoring method, and show that the PMD and chirp induce significant CD monitoring errors. We propose a CD monitoring technique to suppress these effects. Experiment results show that the CD monitoring errors induced by PMD and chirp fluctuation are greatly suppressed.

Optical signal generation at millimeter-wave repetition rates using semiconductor lasers with pulsed subharmonic optical injection

A new technique is presented and investigated systematically which generates optical signals at millimeter-wave repetition rates from a semiconductor laser, without the need for an intracavity saturable absorber. Optical pulses are generated from a long-cavity semiconductor laser with a repetition rate equal to its cavity resonant frequency by injecting short optical pulses at one of the cavity resonance subharmonics. A rate-equation model is proposed to explain the mechanism of this subharmonic optical injection method. Optical pulses with repetition rates of 35 and 56 GHz are generated using the proposed scheme from a semiconductor laser with a distributed Bragg reflector and a Fabry-Perot laser diode, respectively. The performance of the generated pulses is also evaluated in terms of detected RF power at the repetition frequencies, the subharmonic suppression ratio, phase noise, and timing jitter as a function of frequency detuning, injected optical power, laser bias current, and, finally, the subharmonic number. It is found that the generated optical pulses exhibit large subharmonic suppression ratio (>17 dB), large locking ranges >400 MHz, low levels of phase noise (/spl sim/-93 dBc/Hz@10 kHz) and timing jitter (<0.41 ps over 100 Hz to 10 MHz), and large tolerance to variations in operating parameters.