被动锁模光纤激光器中双波长脉冲的产生

报道了从一个典型的基于非线性偏振旋转被动锁模光纤激光器中产生双波长锁模脉冲的研究。双折射诱导的波长相关腔传输使得激光器能同时在2个或多个波长上振荡,本文设计的激光器中最多有3个波长同时产生。由于偏振相关隔离器(PDI)引入的另外偏振相关腔损,通过调节偏振控制器(PC),3个波长中的任意2个能同时共振,并同时锁模。此外,双波长脉冲中2个不同波长的脉冲会相互作用,并通过交叉相位调制形成各种各样的调制格式。     

Subpicosecond pulse compression and Raman generation using amode-locked erbium-doped fiber laser-amplifier

Pulses of 20 ps duration from a 1536-nm erbium-doped fiber laser mode-locked at 10 MHz were soliton-compressed in a 1-km fiber to 1.5 ps. The pulses were then amplified in an erbium-doped fiber amplifier and compressed in a second fiber to less than 300 fs. Pulses give rise to stimulated Raman scattering in fibers; the direct output from the erbium fiber laser-amplifier has sufficient peak power to pump fiber Raman lasers. The sources can be made very compact and, with laser diode pumping, an all-fiber design can be realized. Such sources will find use in high-speed optical and electrooptical sampling instrumentation. Peak powers are high enough to study the nonlinear fiber effects that usually require a high-power Nd:YAG or color center laser     

High-repetition-rate optical pulse generation using a rationalharmonic mode-locked fiber laser

Rational harmonic mode locking takes place in an actively mode-locked fiber laser when the modulation frequency f_m=(n+1/p)f_c, where n and p are both integers and f_c is the inverse of the cavity round-trip time, the 22nd order of rational harmonic mode locking has been observed when f_m ≈1 GHz. An optical pulse train with a repetition rate of 40 GHz has been obtained using a modulation frequency f_m=10 GHz. The theory of rational harmonic mode locking has also been developed. The stability of the mode-locked pulses is improved considerably when a semiconductor optical amplifier is incorporated into the fiber laser cavity. The supermode noise in the RF spectrum of a mode-locked laser is removed for a certain range of current in the semiconductor optical amplifier     

Multiwavelength generation in a Raman fiber laser with sampled Bragg grating

Simultaneous continuous-wave multiwavelength operation of a Raman fiber laser is demonstrated with sampled Bragg grating (SBG) at room temperature. The characteristics of multiwavelength fiber ring laser can be easily controlled by adjusting the parameters of the SBG, including the sampling period and the sampling length. In the proposed fiber laser, stable four oscillating wavelengths with 100- and 50-GHz spacing has been achieved, respectively, as well as five oscillating ones with a wavelength spacing of only 25 GHz by varying the sampling period of the SBG.     

80-GHz pulse generation from a repetition-rate-doubled FM mode-locking fiber laser

We demonstrated a simple method to realize repetition-rate-doubling in a frequency modulation (FM) mode-locking fiber laser. The mode-locking of the laser is based on converting FM modulation to amplitude modulation by using a phase-modulated optical fiber loop mirror, which is formed by a phase modulator and an additional coupler only. With 40-GHz modulation, we obtained 80-GHz 1.74-ps transform-limited pulse train in the experiments.     

级联拉曼光纤激光器

只要具备合适的泵源，拉曼光纤激光器可以在很大的波长范围获得激光输出，并可进行宽带调谐。本文从结构、原理和工作特性范围方面对三类级联拉曼光纤激光器的最新进展进行了系统的概述，并指出了其发展趋势。     

Streak camera investigation of Raman pulse generation and propagation in an optical fiber

Stimulated Raman scattering ofQ-switched and mode-locked Nd:YAG laser pulses at 1.06 μm in a 120-m-long single-mode fiber has been investigated experimentally. A Photochron IIA Synchrosan streak camera with picosecond resolution was used to give time resolved detection of the first four order Stokes-Raman pulses at 1.12, 1.18, 1.24, and 1.31 μm. It has been shown that in traversing the fiber the fundamental and the first two order Stokes were substantially shortened and that the Stokes pulses were asymmetrical with sharper leading edges.     

Smoothly wavelength-tunable picosecond pulse generation using a harmonically mode-locked fiber ring laser

A simple design of a stable, smoothly wavelength-tunable picosecond pulse generator has been demonstrated using a dispersion-tuned, harmonically mode-locked fiber ring laser with a directly modulated semiconductor optical amplifier (SOA). The SOA functions as both a polarization-insensitive mode locker and a supermode noise suppressor. Near-linearly chirped pulses are generated and compressed to less than 4 ps when the intracavity dispersion is anomalous while 11-ps, near-transform-limited pulses are generated without compression when the dispersion is normal. Smooth wavelength tuning is achieved over more than 11 nm by only tuning the modulation frequency and pulse characteristics are stable over the entire tuning span. A simple numerical model successively simulates the operation principle of the system. The tuning range is determined by both the gain profile and the total intracavity dispersion. The dispersion and the SOA ensure the long-term stability of the system.     

Single-pass Raman generation pumped by a mode-locked laser

Single-pass Raman generation pumped by a mode-locked Nd:YAG laser is investigated for long-span and low-loss fibres. The peak wavelength of the first Stokes jumps dramatically from 1.114 ?m to 1.12 ?m at 1.65 W average input power. The first Stokes increases rapidly between the inputs of 1.65 W and 2.1 W. These characteristics of single-pass stimulated Raman scattering are discussed in terms of group velocity matching.     

Distributed feedback fiber Raman laser

We analyze the properties of a distributed feedback fiber laser based on Raman amplification. Such a laser is quite practical and has a number of novel properties. We model numerically the laser dynamics, analyze in detail the role of the nonlinear refractive index of the fiber and argue on the optimal design parameters     

A fiber Raman ring laser

A fiber Raman ring laser was synchronously pumped by a cavity-dumped argon laser. The Raman laser was tuned with either a piezoelectric intracavity interferometer or by varying the pump pulse rate.     

Gold nanoparticles film for Q-switched pulse generation in thulium doped fiber laser cavity

Passively Q-switched thulium doped fiber laser (TDFL) has been successfully demonstrated using gold nanoparticles (GNPs), which were embedded into polyvinyl alcohol as saturable absorber (SA). The stable self-starting Q-switched laser was generated to operate at 1 891 nm when a tiny piece of the prepared film was slot in between two fiber ferrules and incorporated into the laser cavity. The repetition rate can be adjusted from 48.54 kHz to 49.64 kHz while the pulse width decreased from 3.52 μs to 2.38 μs with the increase of 1 550 nm pump power from 840 mW to 930 mW. The corresponding pump power output power linearly increased from 3.62 mW to 6.3 mW with a slope efficiency of 2.53%. The maximum peak power and pulse energy were recorded at about 39 mW and 0.12 µJ, respectively at pump power of 930 mW. The Q-switching operation was caused by the surface plasmon resonance absorption of GNPs.     

用于激光脉冲整形的电脉冲产生技术

介绍了一种用于激光脉冲整形的超宽带脉冲产生方法.电路中利用阶跃恢复二极管(SRD)载流子可控、截止速度快的特点,采用对阶跃恢复二极管进行串并联相结合的方法设计了超宽带脉冲产生电路.给出了实际电路的测试结果,并且对实验结果在物理层面上进行了理论分析,实验结果与理论分析结果吻合.此脉冲产生电路可输出幅度约10V,脉冲宽度约...     

超宽光谱类噪声脉冲光纤激光器

报道了一种全光纤超宽带光谱的类噪声脉冲锁模光纤激光器。为了加宽锁模光谱,利用腔内色散管理和非线性技术,使在58m腔内具有小的反常色散,平均色散系数为0.12 ps/nm/km。实验获得了超过1300nm--1750nm超宽带光谱锁模类噪声脉冲,光谱20-dB带宽达到362nm,3-dB带宽达到102nm。类噪声脉冲的光谱宽度远超过掺铒光纤的增益带宽。     

Frequency tuning and pulse generation in a fiber laser with anintracavity semiconductor active filter

The authors demonstrate optical frequency tuning by direct electrical means as well as FM and AM mode-locking in an erbium-doped fiber laser with an intracavity distributed Bragg reflector active filter/modulator. They obtained a 6 nm discrete tuning range and pulses of 38 and 78 ps duration in AM and FM mode-locking, respectively     

High-power supercontinuum generation in a nested linear cavity involving a CW Raman fiber laser

We construct a novel nested linear cavity configuration to generate supercontinuum (SC) under continuous-wave pump. With this structure, stimulated Raman scattering and four-wave mixing can affect the whole region of the SC spectrum while the pump line is removed outside of the continuum, and a symmetrical spectrum can be obtained. The properties of the structure are demonstrated by using 3.5-km single-mode fiber, and an SC centered at 1315 nm with the bandwith of 102 nm and the output power of 1.3 W is achieved. By tuning the feedback fiber Bragg grating, we can easily adjust the spectral shape of SC to fit different requirement.     

Supercontinuum generation pumped by a regeneratively mode-locked fiber laser

Supercontinuum（SC） generation in a dispersion-shifted fiber（DSF） pumped by a 10 GHz regeneratively mode-locked fiber laser（RMLFL） is presented. Optimization of pump wavelength leads to a 20 dB bandwidth of 58.73 nm,which covers the whole C band and part of L band. Using an angle-tuning thin film filter, multi-wavelength and pico-second pulse trains of low chirp could be chosen from the SC spectrum. Amplified spontaneous emission（ASE） induced degeneration of the achieved pulse trains is observed and discussed.     

半导体激光器生成双波长超窄脉冲的实验研究

描述了一种用腔外注入方式调制增益的法布里珀罗半导体激光器产生双波长超窄脉冲的简单方法，腔外注入功能部分包含一个直流工作的法面里珀罗半导体激光器，一个3dB光耦合器和两个布喇格型光纤光栅。双波长的选择和间距通过调节光栅为实现，文中描述的系统实现了在10nm的调节范围内边模压制率优于17dB的理想结果。整个系统简单、成本低。     

Coherent pulse generation with a GaAlAs laser by active modelocking

A c.w. GaAlAs laser is modelocked by gain modulation. 60 ps coherent pulses are obtained at a repetition frequency of 433 MHz.     

40-GHz transform-limited pulse generation from FM oscillation fiber laser with external cavity chirp compensation

A 40-GHz frequency modulation oscillation fiber laser is demonstrated and the continuous-wave (CW) output is used for generating a high repetition rate short pulse train by external cavity chirp compensation. A 1.37-ps transform-limited pulse is obtained from its chirped, 488.1-GHz width CW output.