Qiang Wang

Gaussian-like dual-wavelength prescaled clock recovery with simultaneous frequency-doubled clock recovery using an optoelectronic oscillator

A novel multifunctional frequency-doubling optoelectronic oscillator (FD-OEO) mainly based on a Mach-Zehnder modulator (MZM) cascaded with a phase modulator (PM) and a subsequent optical bandpass filter (OBPF) is proposed. We experimentally demonstrate simultaneous operations of frequency-doubled optical clock (FD-OC) recovery, low-duty-cycle dual-wavelength prescaled OC recovery and error-free fourfold time division demultiplexing with the proposed OEO injected with a 4 × 25-Gb/s optical time-division-multiplexing (OTDM) signal. We show that the proposed FD-OEO operates well for both the differential phase shift keying (DPSK) and on-off keying (OOK) modulation formats. The extracted dual-wavelength prescaled OC is proved to be nearly transform-limited with Gaussian-like shape. Furthermore, all four 25-Gb/s tributaries can be selectively demultiplexed by adjusting the phase shifters in the OEO loop. The power penalty at a bit error rate (BER) of 10(-9) is measured to be 2.4 dB, 1.2 dB for the best channel for DPSK signal and to be 2.5 dB, 1.1 dB for the best channel for OOK signal. In addition, as an extra benefit of the OEO, low-phase-noise prescaled electrical clock (EC) is also extracted.

Cost-effective Optical Nyquist Pulse Generator with Ultra-flat Optical Spectrum Using Dual-parallel Mach-Zehnder Modulators

Rectangular-shaped optical frequency comb generation with Nyquist temporal waveforms using dual-parallel Mach-Zehnder modulators is proposed. Nyquist pulse with 3.66% duty cycle and 25-tone frequency combs with flatness within 0.5 dB is generated.

Effective optical clock recovery and simultaneous fourfold demultiplexing of OTDM signal using an optoelectonic oscillator.

We propose and demonstrate a novel scheme for clock recovery and simultaneous fourfold optical time-division demultiplexing using a dual-parallel Mach-Zehnder modulator based optoelectronic oscillator. 25-GHz prescaled optical clock with a 23% duty cycle and a 22-dB extinction ratio is successfully extracted from both 100-Gb/s on-off keying (OOK) and differential phase-shift keying (DPSK) optical time-division-multiplexing (OTDM) signal. The timing jitters (100 Hz to 10 MHz) are measured to be 195.9 fs and 125.6 fs for the optical clock extracted from the 100-Gb/s OOK and DPSK signal, respectively. Error-free optical time-division demultiplexing is also achieved simultaneously with clock recovery. By adjusting the phase shifter in the OEO loop, all four channels can be selectively demultiplexed. The power penalties at a bit error rate (BER) of 10⁻⁹ for the four demultiplexed channels are measured to be between 0.8 dB and 1.2 dB for the OOK signal and between 0.9 dB and 1.5 dB for the DPSK signal.

Optical Time-Division Demultiplexing Using a Time-Lens-Assisted Mach–Zehnder Modulator

We propose to use a diverging time lens to equivalently minimize the time window of a LiNbO3 Mach-Zehnder modulator (MZM) and promote its capability in optical time-division demultiplexing applications. A single MZM is demonstrated experimentally for fourfold 100-Gb/s tributary demultiplexing assisted with a phase modulator based diverging time lens. Error-free detection is achieved for all four channels and the power penalty at a bit-error-rate of 10-9 is 2.4 dB, 1.1 dB for the best channel.

Low-Phase-Noise Clock Recovery From NRZ Signal and Simultaneous NRZ-to-RZ Format Conversion

We propose and demonstrate an improved optoelectronic oscillator based on a dual-parallel Mach-Zehnder modulator for simultaneous low-duty-cycle and low-phase-noise clock recovery from NRZ signal and wavelength-preserved NRZ-to-RZ format conversion. A 25-GHz optical clock with a 25% duty cycle and a 22.5-dB extinction ratio is successfully extracted from the incident 25-Gb/s NRZ signal. Benefiting from the intrinsic property of the optoelectronic oscillator, an electrical clock with a 174-fs root-mean-square timing jitter (100 Hz-10 MHz) is also achieved. Simultaneously, error-free wavelength-preserved NRZ-to-RZ format conversion with a -2-dB power penalty at a bit error rate of 10-9 is demonstrated.

Multifunctional Optoelectronic Oscillator Based on Cascaded Modulators

We propose and experimentally demonstrate a multifunctional optoelectronic oscillator (OEO) mainly composed of a phase modulator in tandem with a dual-parallel Mach-Zehnder modulator. Simultaneous operations of low-phase-noise ultra-flat optical frequency comb (OFC) generation, prescaled electrical clock (EC) recovery, and error-free fourfold demultiplexing of an injected 4 × 25-Gb/s optical time-division multiplexing differential phase-shift keying signal are achieved with the proposed OEO. The generated nine-tone OFC has a flatness within 0.7 dB. The timing jitters of optical and EC signals are 117 and 112 fs, respectively.

25-GHz dual-wavelength pedestal-free pulse source based on single-driven dual-parallel Mach-Zehnder modulator and Mamyshev reshaper

Abstract. A dual-wavelength optical Gaussian pulse generation scheme based on a single-driven dual-parallel Mach-Zehnder modulator with subsequent Mamyshev reshaping is proposed. Experimental results show that nearly chirp-free Gaussian pulses with a full width at half maximum of 2.7-ps and a repetition rate of 25-GHz on 2 wavelengths are achieved simultaneously. By changing the central wavelengths of the continuous wave light and the optical bandpass filter, nearly transform-limited optical Gaussian pulses are obtained over the C-band. The pulse source is further employed in a 100-Gbit/s on–off keying optical time division multiplexing transmission system. Error-free bit error rate performance is also achieved, which confirms the high pulse quality.

Time-to-frequency conversion based on nonlinear pulse shaping

A precise time-to-frequency conversion based on nonlinear pulse shaping is demonstrated. Simulation results also show the scheme can be applied to arbitrary waveform.

Optical Gaussian pulse generator using phase modulator based spectral slicing and compression

A 25-GHz 3-ps optical Gaussian pulse generator using phase modulators is experimentally demonstrated with wavelength tunability over C-band. Error-free 100-km transmission of 100-Gb/s OTDM signal is achieved with it.

A short optical pulse source based on chirp compression and Mamyshev 2R regenerator for 200-Gbit/s OTDM System

We propose and demonstrate a simple and robust short pulse source based on chirp compression scheme and Mamyshev 2R regenerator. Pedestal-free optical pulse with repetition rate of 25 GHz, FWHM of 1.33 ps and RMS timing jitter of 112.81fs (100-Hz∼10-MHz) is generated experimentally. Moreover, it is successfully applied to a 200-Gbit/s OTDM system by multiplexing in time domain.