Lou Cai-Yun

Novel method to simultaneously compress pulses and suppress supermode noise in actively mode-locked fiber ring laser

Nonlinear polarization rotation is used to compress pulses or suppress supermode noise in mode-locked fiber lasers at different situations. In this letter, we propose a novel method to simultaneously realize the above two effects by exploiting nonlinear polarization rotation in actively mode-locked fiber ring laser at a special state. A simple model derived by theoretical analysis is given to explain this phenomenon. We have also investigated the different transmission situations of nonlinear polarization rotation in the 10-GHz actively mode-locked fiber ring laser. Experimental observations agree well with theoretical predictions.

Generation of Pedestal-free 10 GHz Pulses from a Comb-Like Dispersion Profiled Fiber Compressor and Its Application in Supercontinuum Generation

We built a pulse compressor using a comb-like dispersion-profiled fiber (CDPF). The CDPF consists of 12-segment fibers with the dispersion alternatively high and low. Using this compressor and a 17 dBm Erbium-doped fiber amplifier, the 10 GHz, 12 ps pulses generated from an actively mode-locked Er3+ doped fiber ring laser was compressed to ~ 2 ps without pedestal. We also show that compared with the high order soliton pulse compressor, the power efficiency can be doubled in supercontinuum generation by using the pump pulses compressed by this CDPF compressor.

Effects of pulse chirp on supercontinuum produced in dispersion decreasing fibre

The supercontinuum (SC) source plays a key role in wavelength division multiplexing over the optical time division multiplexing (WDM/OTDM) transmission system. The SC produced in dispersion decreasing fibre (DDF) is wider and flatter than that produced in dispersion shifted fibre (DSF). In this paper, a SC producing process in DDF is numerically simulated, the effects of pump pulse chirp on the SC width and flatness are initially studied and the corresponding theoretical explanations are given. Particularly, we have analysed and compared the evolutions of the SC along DDF pumped by different chirp pulses. Several valuable conclusions are obtained.

A Stable Ultrashort Pulse Generator Based on EAM and Well-Designed Compressor for Applications in 160 Gbit/s OTDM Networks

A stable 10 GHz ultrashort pulse generator consisted of an electroabsorption modulator (EAM) and a well-designed fibre-based pulse compressor is proposed and demonstrated experimentally. The obtained short pulse has high extinction ratio, no pedestal, low timing jitter, and FWHM of only 2.4 ps. The excellent performance of multiplexing from 10 GHz to 160 GHz confirms the potential of the generator for applications in 160 Gbit/s optical time-division-multiplexing (OTDM) systems.

Multiwavelength Dispersion-Tuned Actively Mode-Locked Erbium-Doped Fibre Ring Laser with Gain Competition Suppression

Multiwavelength dispersion-tuned actively mode-locked erbium-doped fibre ring laser is demonstrated by incorporating a section of highly nonlinear fibre (HNLF) in the laser cavity. The HNLF and the time gate element (modulator) in the fibre laser successfully suppress the gain competition in the erbium-doped fibre, and thus enable multiwavelength operation. Simultaneous generation of 10 GHz pulses up to eight different wavelengths is achieved. Wavelength, spacing and modes number tuning are investigated by changing fibre cavity length, dispersion, and erbium-doped fibre amplifier power, respectively.

A polarization controlled multiwavelength Er-doped fiber laser

Without any stabilization equipment, multiwavelength laser oscillation was realized in an Er-doped fiber, based on a section of standard multimode optical fiber which was twined as a polarization controller (PC). The number of lasing wavelengths and wavelength spaces can be controlled by the state of the PC.

Influence Factors of an All-Optical Recovered Clock from Two-Section DFB Lasers

All-optical clock recovery by a two-section DFB laser with different injection wavelengths is demonstrated experimentally at 38.5 GHz. An optical clock with a root-mean-square timing jitter of 250 fs and an extinction ratio of 12.1 dB is obtained with 1551 nm injection. The timing jitter of the recovered clock is further investigated for various intensity ratios of the two DFB emission modes.

Influence of degenerate four-wave mixing on the performance of supercontinuum-based multiwavelength optical source

length optical source has been investigated in detail experimentally and theoretically. Numerical simulation results show that the degenerate FWM effect has a deteriorative influence on the spectral uniformity and the optical signal-to-noise ratio (OSNR) of supercontinuum-based optical source, and by suppressing degenerate FWM effect the performance enhancement of the supercontinuum can be achieved successfully. These results are also confirmed by our experiments. Experimentally, by suppressing degenerate FWM the crosstalk of adjacent channels to the filtered channel can be reduced by as much as 15 dB, and consequently the measured receiver sensitivity at 10 Gbit/s for the filtered optical source is improved from 1.7 to 17.8 dBm.

Theoretical Design of Fibre-Based Digital Autocorrelator for Completely Characterizing Ultrashort Pulses

A new idea to design fibre-based digital autocorrelation technique for completely characterizing ultrashort pulses is presented. Feasibility of the design is demonstrated by theory. The technique is found to promise minimized optical alignment requirements, compact configuration, high time resolution, and short measurement time.

A Novel 3R Regeneration and Its Application on PMD Mitigation

A novel 40 Gbit/s reamplified-reshaping-retiming (3R) regenerator is proposed and demonstrated based on a two-ring injection mode-locked fibre laser as the clock recovery and the electro-absorption modulator of the reshaping optical decision. A numerical model describing the cross-absorption modulation effect in a bulk electroabsorption modulator is presented. By this model, the shape and the extinction ratio of the optical decision gate is improved by optimizing the parameters. The polarization mode dispersion mitigation by the 3R regenerator is experimentally demonstrated at 40 Gbit/s with improved bit-error-rate (BER) performance when the differential-time-delay value is set up to 40% of bit interval.