Multi-frequency low-noise semiconductor laser sources enabling advancement of resonant fiber optic gyroscopes including performance over temperature

Le résumé fourni par la source

We present multi-frequency low-noise semiconductor laser sources for resonant fiber optic gyroscope (RFOG) interrogation that have enabled excellent gyro stability over temperature. Each laser source includes three distributed feedback semiconductor laser chips coupled with micro-lenses to multi-component silicon photonics (SiP) chips. A first laser, the master, is locked to the RFOG with a Pound-Drever-Hall loop. Two slave lasers are optically phase-locked to the master laser with electrical loop bandwidths of 100 MHz. The SiP chips perform beat note detection and several other functions, such as phase and intensity noise suppression. The lasers and SiP chips are packaged in an optical engine that is controlled by compact low noise electronics. The fiber pigtails are connected to the RFOG so that light is sent in clockwise and counterclockwise directions. Tracking of the RFOG resonance frequencies in both directions allows rotation sensing. An ultra-stable differential frequency noise floor of 0.05 Hz/rt-Hz was obtained between the lasers and the coil resonator which was instrumental in achieving results for the RFOG over 60˚ C operating temperature range. The corresponding angle random walk level is less than 0.01 ˚/rt-hr and was not limited by laser differential frequency noise. The gyroscope bias drift over the tested temperature range was maintained within 0.005 ˚/hr, the best-ever published RFOG performance over temperature to date.

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