Abstract
We investigate a new configuration of a mode-locked fiber laser by using a nonlinear polarization rotation-based design to generate soliton pulses with low repetition rate. Unlike with previously reported configurations, we introduce a Faraday mirror after the first half of the cavity length to counteract the nonlinear polarization rotation effects. The total cavity length is 437 m including a 400-m long twisted SMF-28 fiber. The fiber was twisted to cancel the linear birefringence and to ensure that the polarization ellipticity is not altered as the pulse travels along the fiber. The strict control of polarization yields a stable relation between the polarization state of the pulses propagating in the cavity and the regimes of generation. Depending on the polarization state we observed three different emission regimes, the single soliton regime (SR), conventional noise-like pulses (NLP) and noise-like square-waveform pulse (NLSWP). In the SR, a 467.2 kHz train of solitons was obtained with pulse duration of 2.9 ps at 1558.7 nm.
Highlights
Ultrafast lasers have attracted significant interest due to their potential for applications like surgery [1], high-precision micromachining [2] and multiphoton microscopy (MPM) [3]
We investigate a new configuration of a mode-locked fiber laser by using a nonlinear polarization rotation-based design to generate soliton pulses with low repetition rate
A high-repetition train of ultrashort pulses causes the effect of thermal accumulation [5,6] which can be beneficial in some cases, it is undesirable for applications such as MPM
Summary
Ultrafast lasers have attracted significant interest due to their potential for applications like surgery [1], high-precision micromachining [2] and multiphoton microscopy (MPM) [3]. In the last case the fiber soliton sources can be especially useful because of their capacity of generating ultrashort pulses in the wavelength range from 1530 nm to 2000 nm using Er, Tm, Ho doped fibers and the effect of soliton self-frequency shift [4]. A high-repetition train of ultrashort pulses causes the effect of thermal accumulation [5,6] which can be beneficial in some cases, it is undesirable for applications such as MPM. Because the repetition rate of a mode-locked laser is inversely proportional to its resonator length, the repetition rate can be reduced by lengthening the cavity. In contrast to solid-state lasers, which require critical alignment, fiber lasers are more prone to achieve lower repetition rates with the convenience and simplicity of elongating a fiber cavity
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
