Ultra-wideband wavelength-swept laser with a 440nm scanning range using four SOAs

Broadband wavelength-swept lasers (WSLs) have many advantages in multi-point sensing and dynamic sensing in fiber optic sensors. In this paper, we report the implementation of an ultra-wideband WSL source with a 440 nm scanning range. It is composed of a polygonal scanning mirror-based wavelength tunable filter (PSM-TF) and four semiconductor optical amplifiers (SOAs). It consists of two independent gain media and PSM-TF, each gain media is configured in a Mach- Zehnder interferometer, and the central wavelengths are approximately 1250 nm and 1450 nm, respectively. The WSL achieved a 10-dB spectral bandwidth of 440.8 nm in the spectral domain and a temporal output duration of 323.8 μs at a scanning frequency of 2.338 kHz. The conversion ratio between the spectral and time domains over the scanning range was determined to be 1.361 nm/μs. The duty cycle was measured to be 75.7% from the oscilloscope trace, and the free spectral range in the spectral domain was calculated to be approximately 582.3 nm.