An 88 fs fiber soliton laser using a quantum well saturable absorber with an ultrafast intersubband transition

We demonstrate a 1.5 μm passively mode-locked fiber laser using an intersubband transition (ISBT) in a quantum well as a saturable absorber. The saturable absorption characteristic of faster than 1 ps in the ISBT was utilized for femtosecond pulse generation. We designed the laser cavity as a soliton laser, which enabled us to generate a stable pulse. As a result, an 88 fs, 42 MHz soliton pulse was successfully generated.