Linewidth and frequency jitter measurement of an erbium-doped fiber ring laser by using a loss-compensated, delayed self-heterodyne interferometer

The single-mode line width of erbium-doped, single-frequency, fiber ring laser has been measured by using a newly developed loss-compensated delayed self-heterodyne interferometer that has a resolution of less than 600 Hz. The natural linewidth is determined to have an upper bound of less than 2 kHz. In addition, frequency jitter was found to be dominant over the natural linewidth, yielding an effective linewidth of approximately 4 kHz

An improved delayed self-heterodyne interferometer for linewidth measurements

The authors demonstrated a delayed self-heterodyne interferometer with a recirculating delay, in which loss was partially compensated by an erbium-doped fiber amplifier. A resolution limit of 606 Hz was achieved with an 11-km fiber delay line, as compared to 18.2 kHz for the standard single-pass case. The possible effect of spectral broadening due to amplifier noise is considered and found to have a negligible effect on the system performance

Frequency locking of an erbium-doped fiber ring laser to an external fiber Fabry-Perot resonator

An all-fiber, single-frequency, erbium-doped ring laser has been frequency locked to a resonance peak of an external fiber Fabry-Perot resonator by the Pound-Drever technique. In addition, feedback to the mode selection filter in the laser resonator eliminates occasional mode hopping completely, resulting in frequency-locked, stable, single-frequency operation of the laser for periods of several hours

Reduction of the intensity noise from an erbium-doped fiber laser to the standard quantum limit by intracavity spectral filtering

The high frequency intensity noise of a tandem fiber Fabry–Perot erbium-doped fiber ring laser is reduced to the standard quantum limit, with a 0.5 dB experimental uncertainty. Noise reduction of >~14 dB is achieved by intracavity spectral filtering of weak side modes using a narrow-band fiber Fabry–Perot etalon