We implemented an optical frequency standard based on noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) at 1.39 μm. The emission frequency of an extended-cavity diode laser was actively stabilized against the center of the 44;1 → 44;0 transition of the H2 18O ν1 ν3 band, under optical saturation conditions. The nonlinear regime of laser-gas interaction was reached by using an optical cavity with a finesse of about 8700. By filling it with an 18O-enriched water sample at a pressure of a few Pa, the Lamb dip could be observed with a full width at half-maximum of about 2 MHz. Absolute frequency stabilization was obtained by locking the cavity resonance to the center of the sub-Doppler signal, which was provided by the NICE-OHMS technique under the dispersion regime of operation. An Allan deviation analysis demonstrated a relative frequency stability of ∼5 × 10−13 for an integration time of 1 s. For longer integration times, the flicker frequency noise floor set the stability at the level of 4 × 10−14.
Absolute frequency stabilization of an extended-cavity diode laser by means of noise-immune cavity-enhanced optical heterodyne molecular spectroscopy
Fasci E;CASTRILLO, Antonio;GIANFRANI, Livio
2014
Abstract
We implemented an optical frequency standard based on noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) at 1.39 μm. The emission frequency of an extended-cavity diode laser was actively stabilized against the center of the 44;1 → 44;0 transition of the H2 18O ν1 ν3 band, under optical saturation conditions. The nonlinear regime of laser-gas interaction was reached by using an optical cavity with a finesse of about 8700. By filling it with an 18O-enriched water sample at a pressure of a few Pa, the Lamb dip could be observed with a full width at half-maximum of about 2 MHz. Absolute frequency stabilization was obtained by locking the cavity resonance to the center of the sub-Doppler signal, which was provided by the NICE-OHMS technique under the dispersion regime of operation. An Allan deviation analysis demonstrated a relative frequency stability of ∼5 × 10−13 for an integration time of 1 s. For longer integration times, the flicker frequency noise floor set the stability at the level of 4 × 10−14.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
