Low-Noise Narrow-Linewidth Fiber Laser at 1550 nm (June 2003)

TLDR

The study presents a compact integrated fiber laser delivering over 200 mW of output power. The laser is a compact integrated fiber device that employs thermal wavelength tuning and piezoelectric modulation up to 10 kHz. It achieves a linewidth below 2 kHz, a coherence length exceeding 5 km, mode stability better than ±10 MHz over hours, and a shot‑noise‑limited RIN except for a relaxation‑oscillation peak reduced to ~–130 dB/Hz at 1 MHz by negative‑feedback control.

Abstract

We present a compact integrated fiber laser with more than 200 mW of output power. It combines polarized fiber output with very narrow linewidth of less than 2 kHz. The coherence length of the laser is measured to be longer than 5 km. The laser features high mode stability of less than /spl plusmn/10 MHz over hours. The relative intensity noise (RIN) spectrum is dominated by a peak at the relaxation oscillation frequency and is shot-noise limited otherwise. The RIN peak at 1 MHz is reduced to /spl sim/-130 dB/Hz by integrating a negative feedback circuit. In addition to thermal wavelength tuning, the laser frequency can be modulated at a bandwidth of up to 10 kHz via the piezoelectric effect.