Limitations of frequency stability transfer in the near infrared using a fiber-based ring cavity: erratum.

We have detected a calibration error in the experiments presented in Opt. Lett.47, 5465 (2022)10.1364/OL.472887.

Limitations of frequency stability transfer in the near infrared using a fiber-based ring cavity.

We describe a fiber ring cavity for transferring frequency stability from a metrological optical reference at 1542 nm to tunable lasers covering 100 nm around 1.55 µm and show a stability transfer to the 10-15 level in relative value. The optical length of the ring is controlled by two actuators: a cylindrical piezoelectric tube (PZT) actuator on which a portion of the fiber is coiled and glued for fast corrections (vibrations) acting on the length of the fiber, and a Peltier module for slow corrections acting on its temperature. We characterize the stability transfer and analyze the limitations imposed by two critical effects in the setup: Brillouin backscattering and the polarization modulation generated by the electro-optic modulators (EOMs) used in the error signal detection scheme. We show that it is possible to reduce the impact of these limitations to a level below the detection threshold imposed by the servo noise. We also show that in the long term, the limitation to the stability transfer is a thermal sensitivity of -550 Hz/K/nm which could be reduced by active control of the ambient temperature.

Compact fiber-ring resonator for blue external cavity diode laser stabilization.

We demonstrate a compact and low-cost all-fiber-based locking setup for frequency-noise suppression of a 420 nm external-cavity diode laser. Frequency noise reduction in the 100 Hz to 800 kHz range is demonstrated up to 40 dB associated with a linewidth narrowing from 850 kHz to 20 kHz for 10 ms integration time. This simple locking scheme might be implemented for a large range of wavelengths and can be integrated on a small footprint for embedded applications requiring narrow linewidth blue laser diodes.

All-fiber ring-cavity for frequency stability transfer at 1.55 µm.

A compact setup for transferring the stability of a metrological frequency reference at 1.55 µm is described. One mode of a fiber-ring cavity is frequency-locked onto the reference. The stability transfer is achieved by locking an extended-cavity diode laser, tunable over 100 nm onto one cavity mode. Once locked, this tunable laser exhibits a relative frequency stability close to 10-12 for integration times from 1 to 3000 s (minimum of 6·10-13 at 10 s). We show that this stability limitation is due to the polarization fluctuations' sensitivity of the fiber optic components. Using a second cavity, the frequency stability transfer over 58 nm is demonstrated at a level of 4·10-12. Associated with a local frequency reference and with an efficient acoustic and thermal insulation, this compact setup is intended for embedded metrological applications.