An optical pulse generation scheme based on an ultra-short chirped seed pulse generator followed by a dual-stage fiber-based nonlinear pulse processing stage is proposed and demonstrated experimentally. After phase modulation and linear-chirp compensation, optical seed pulse with a duty cycle of 9.8% and an obvious pedestal is obtained.
View Article and Find Full Text PDFWe experimentally demonstrated all-optical NOR, OR and AND logic gates at 100 Gb/s with a single semiconductor optical amplifier (SOA) assisted by optical filtering. The logics can be conveniently reconfigured by deploying or not continuous wave (CW) light at the input of the SOA and adjusting the tunable optical band pass filter (OBPF) at SOA output. Correct logic functions and high quality of the output signals can be achieved as proved by clear eye opening and bit error rate (BER) measurement.
View Article and Find Full Text PDFWe demonstrate a monolithic dual-mode amplified feedback laser for photonic millimeter-wave generation and all-optical clock recovery. Dual-mode lasing with beating frequency around 100 GHz was realized by using a single-mode distributed feedback (DFB) laser with a short feedback cavity that was integrated by simple quantum-well intermixing technology. By tuning the bias currents of the laser sections, the beating-frequency can be continuously tuned from 75 to 109 GHz, almost covering the entire W-band (75-110 GHz).
View Article and Find Full Text PDFAll-optical 2R regeneration of 100-Gb/s on-off-keying (OOK) signal is experimentally demonstrated based on cross gain compression (XGC) effect in semiconductor optical amplifiers (SOAs). It is shown that a high-quality logic-inverted signal and SOAs with faster gain recovery times are the two key enabling factors for obtaining regeneration results at such speeds. BER improvement of 1.
View Article and Find Full Text PDFWe demonstrate a simple, robust, and cost-effective method of generating high-speed multiwavelength picosecond optical pulses. This method is based on chirp compression of phase-modulated light, followed by nonlinear pulse compression and reshaping with a double-side Mamyshev reshaper. We show that this method becomes power efficient when the repetition rate is increased to 25 GHz.
View Article and Find Full Text PDFOptical 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.
View Article and Find Full Text PDFA 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.
View Article and Find Full Text PDFWe 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.
View Article and Find Full Text PDFWe propose to insert group velocity dispersion between cascaded phase and amplitude modulation for ultraflat optical frequency comb (OFC) generation. With the dispersion, the sinusoidally varied chirp of the continuous wave light induced by phase modulation becomes linear within a relatively wide time interval. This is useful to improve the flatness of the generated OFC by directly cascaded phase and amplitude modulation.
View Article and Find Full Text PDFWe demonstrate an all-optical synchronization using an amplified-feedback distributed feedback laser with coherent injection experimentally, which can synchronize 40 GHz degraded signals even with optical signal-to-noise ratio as low as 5 dB, or chromatic dispersion as large as 408 ps/nm. Besides, this optical synchronization has a large range of power operation, i.e.
View Article and Find Full Text PDFA stable 10 GHz pedestal-free short pulse generation scheme consisting of cascaded commercial LiNbO(3) modulators has been proposed and successfully demonstrated experimentally. Fiber-based pulse compression and reshaping stages have been utilized to obtain a 1.38 ps optical pulse train with very little pedestal and 132 fs timing jitter.
View Article and Find Full Text PDFOptical regenerative nonreturn-to-zero (NRZ) to return-to-zero (RZ) format conversion using a lithium niobate phase modulator and a lithium niobate intensity modulator is proposed and demonstrated. The key advantage of the proposed format converter is that the converted RZ signal has a very small pulse width, which can be multiplexed to a higher bit rate using optical time division multiplexing technology. The operation can greatly reduce the timing jitter of the degraded NRZ signal due to the regenerative property of the proposed scheme.
View Article and Find Full Text PDFAll-optical clock recovery for the return-to-zero modulation format is demonstrated experimentally at 40 Gbits/s by using an amplified feedback laser. A 40 GHz optical clock with a root-mean-square (rms) timing jitter of 130 fs and a carrier-to-noise ratio of 42 dB is obtained. Also, a 40 GHz optical clock with timing jitter of 137 fs is directly recovered from pseudo-non-return-to-zero signals degraded by polarization-mode dispersion (PMD).
View Article and Find Full Text PDFA simple and robust all-optical nonreturn-to-zero to return-to-zero (RZ) format converter is demonstrated and investigated using a semiconductor optical amplifier (SOA) and a reconfigurable delayed interferometer. The scheme can be used to convert input signals at different bit rates and obtain converted signals with tunable duty cycles. Format conversion at 10 Gb/s is achieved with a negative power penalty of -4.
View Article and Find Full Text PDFThe authors have proposed and experimentally demonstrated all-optical logic gates using a single SOA and delay interference filtering that enable simultaneous logic functions of OR and NOR at 40 Gbits/s. The proposed scheme, which utilizes the combinative filtering profile of a delay interferometer and an optical bandpass filter, has great merits for use in generating logic outputs with high quality in terms of pulse shape, extinction ratio, and eye diagram. Reconfiguration between the two gates is achieved by adjusting the tunable filter and the delay interferometer.
View Article and Find Full Text PDFWe propose and demonstrate a novel single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber ring laser incorporating a semiconductor optical amplifier. The SOA biased in its low-gain regime greatly reduces the gain competition of the two wavelengths. The stable SLM operation is guaranteed by a passive triple-ring cavity and a fiber Fabry-Perot filter.
View Article and Find Full Text PDFWe propose a simple and stable pulse compression scheme based on a filtering self-phase modulation broadened spectrum in a highly nonlinear fiber. It is found experimentally that under offset filtering the compressed pulse has a better quality compared with center filtering, such as a no pulse pedestal. Furthermore, numerical simulations reveal that the scheme has the potential to improve the pulse extinction ratio during compression.
View Article and Find Full Text PDFWe demonstrated a simple technique to obtain stable room temperature multiwavelength lasing in an erbium-doped fiber laser by the inhomogeneous loss mechanism. Successful reduction of the cross-gain saturation in erbium-doped fiber was achieved by incorporating a section of highly nonlinear fiber (HNLF) and a Fabry-Perot filter (FPF) in the laser cavity. More than 70 wavelengths simultaneous lasing were observed with the same frequency space of 25GHz.
View Article and Find Full Text PDFWe present a theoretical study of a supercontinuum (SC) continuous-wave (cw) optical source generation in highly nonlinear fiber and its noise properties through numerical simulations based on the nonlinear Schrödinger equation. Fluctuations of pump pulses generate substructures between the longitudinal modes that result in the generation of white noise and then in degradation of coherence and in a decrease of the modulation depths and the signal-to-noise ratio (SNR). A scheme for improvement of the SNR of a multiwavelength cw optical source based on a SC by use of the combination of a highly nonlinear fiber (HNLF), an optical bandpass filter, and a Fabry-Perot (FP) filter is presented.
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