Caiyun Lou

Optical Nyquist pulse generation using a time lens with spectral slicing

Optical Nyquist pulse generation based on a time lens with subsequent optical filtering is proposed. A nearly chirp-free 10-GHz 8.1-ps Nyquist pulse generator is experimentally demonstrated. By inserting group velocity dispersion (GVD) between cascaded phase and amplitude modulators, 11 tones ultraflat optical frequency comb (OFC) of 10-GHz frequency spacing within 0.9 dB power variation is obtained. The quasi-rectangular shape spectrum is then filtered out with a tunable rectangular-shaped optical band-pass filter (OBPF) and the quasi-linear chirp is compensated by a segment of standard single mode fiber (SSMF). By changing the wavelength of the continuous wave (CW) light, nearly chirp-free Nyquist pulses over C band are obtained. Furthermore, simultaneous dual-wavelength pulse generation is also demonstrated.

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.

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.

Performance comparison of phase modulated formats in 160 Gb/s transmission system

The performance of DPSK and DQPSK with NRZ, 33% RZ and CSRZ formats are numerically compared and investigated for 160 Gbit/s single channel transmission system. The impairments caused by chromatic dispersion (CD), higher-order chromatic dispersion, nonlinearity and accumulated noise are considered. The primary limitation for those modulation formats in 160 Gbit/s transmission system is investigated.

Optical time-division multiplexing signal processing using electro-optic modulators

We present some optical signal processing methods for optical time-division multiplexing, based on electro-optic modulators. Dual-parallel Mach–Zehnder modulator and time-lens-based signal processing for optical frequency comb generation, optical Nyquist pulse generation and time-domain demultiplexing are realized. Multifunctional optoelectronic oscillators which are capable of performing simultaneous electrical clock recovery, optical clock recovery and demultiplexing are demonstrated with modulators embedded as the key components.

Power-efficient coherent supercontinuum generation by two-color pulses pumping in a highly nonlinear fiber

A coherent supercontinuum generator based on coherent two-color pulses pumping in a highly nonlinear fiber is proposed. Supercontinuum with a 20-dB width of 150 nm is achieved at a modest pump power of 24 dBm.

Supercontinuum generation with high power efficiency in a highly nonlinear fiber pumped by two-color pulses

A power-efficiency supercontinuum generation scheme based on a two-color pulse generator followed by a supercontinuum generation stage is proposed and demonstrated experimentally. After chirp compression and Mamyshev reshaping, pedestal-free two-color pulses are obtained. By two-color pulses pumping in a highly nonlinear fiber at the anomalous dispersion region, supercontinuum with a 20xa0dB width of 207xa0nm is achieved at a modest total pump power of 24xa0dBm, which covers the spectral range from 1456 to 1663xa0nm.

Dual-wavelength clock recovery with simultaneous fourfold demultiplexing using an optoelectronic oscillator

Dual-wavelength Gaussian-like optical clock recovery with simultaneous error-free fourfold demultiplexing of a 100-Gb/s OTDM-DPSK signal are demonstrated with an improved optoelectronic oscillator. Frequency-doubled clock recovery is also achieved.

Subpicosecond pulse generator based on phase modulator and dual-stage nonlinear pulse compressor

We demonstrated a 25-GHz subpicosecond pulse generator based on a single phase modulator and dual-stage fiber-based pulse compressor. Optical pulse with a FWHM of 800 fs was obtained and multiplexed to 400 GHz experimentally.