A wavelength-swept fiber laser is proposed and successfully demonstrated based on a bidirectional used linear chirped fiber Bragg grating (LC-FBG). The wavelength-swept operation principle is based on intracavity pulse stretching and compression. The LC-FBG can introduce equivalent positive and negative dispersion simultaneously, which enables a perfect dispersion matching to obtain wide-bandwidth mode-locking. Experimental results demonstrate a wavelength-swept fiber laser that exhibits a sweep rate of about 5.4 MHz over a 2.1 nm range at a center wavelength of 1550 nm. It has the advantages of simple configuration and perfect dispersion matching in the laser cavity.

A tunable single-longitudinal-mode (SLM) semiconductor optical amplifier (SOA)-based fiber laser based on a dispersion-shifted fiber (DSF) is proposed and successfully demonstrated. SLM operation is obtained due to the spectral narrowing effect resulting from inverse four-wave mixing in a DSF. A tunable optical filter performs wavelength selection function. By inserting a length of DSF in the laser cavity, SLM lasing can possibly be obtained when laser oscillation is stably established after traveling through the DSF many roundtrips. Stable tunable SLM oscillation with a signal-to-noise ratio as high as 65 dB over a wavelength range of about 35 nm is achieved experimentally, and each spectral linewidth is less than 6.5 kHz.