腔内滤波带宽对正色散束缚态孤子形成的影响

Effect of Intracavity Filtering Bandwidth on Bound-State Soliton Generation in Normal Dispersion Regime

以被动锁模正色散掺镱(Yb)光纤激光器为研究对象,实验比较研究了激光腔内滤波带宽对产生正色散束缚态孤子的影响。采用高掺Yb光纤作为增益介质,半导体饱和吸收镜作为锁模部件,获得1064 nm全光纤线型腔锁模激光器。当腔内带通滤波器选用不同带宽(0.2,1.0,1.2,2.3 nm)时,观察到不同的皮秒锁模脉冲状态。在滤波带宽较小(0.2 nm)或较大(2.3 nm)时,仅产生稳定的单脉冲耗散孤子;相反地,在滤波带宽适中(1.0 nm或1.2 nm)时,分别观察到典型的相位差为π和-π/2束缚态耗散孤子,脉宽和脉冲间隔均分别为3 ps和14 ps。将束缚态耗散孤子激光通过主控振荡功率放大技术放大至1.4 W后,将其注入到光子晶体光纤中,获得了750~1600 nm超连续谱(10 dB谱宽),输出功率约为0.7 W,相比传统耗散孤子抽运具有更好的光谱平坦性。

Based on passively mode-locked Yb-doped fiber lasers, the effect of intracavity filtering bandwidth on the generation of bound-state solitons in normal dispersion regime is studied experimentally. A heavily Yb-doped fiber as gain medium and a semiconductor saturable absorber mirror as mode-locked element are used to obtain the 1064 nm all-fiber linear cavity mode-locked laser. Different picosecond mode-locked pulse states are observed when the bandwidths of 0.2, 1.0, 1.2, and 2.3 nm of intracavity bandpass filter are selected. When the filtering bandwidth is narrow(0.2 nm) or broad(2.3 nm), only stable dissipative solitons are obtained. In contrast, when the filtering bandwidth is moderate(1.0 nm or 1.2 nm), we respectively observe the typical π and -π/2 bound-state dissipative solitons both with the pulse width of 3 ps and pulse interval of 14 ps. Then the bound-state soliton laser is amplified to 1.4 W by the master oscillator power amplification technique and injected into a photonic crystal fiber, generating the supercontinuum spectrum with the spectral width of 10 dB in 750-1600 nm and the output power of 0.7 W, whose spectral flatness is better than that pumped by the traditional dissipative soliton.