Toward a 1.54 μm frequency standard with Er-Yb (13C2H2)

A novel Er-Yb:glass quasi-monolithic diode-pumped laser has been developed to realize a high-accuracy frequency standard at 1.54 micrometer based on saturated absorption of isotopic acetylene. This compact oscillator shows low amplitude- and frequency-noise, wide wavelength tunability (approximately 20 nm), and continuous output power in excess of 20 mW with excellent linear polarization (approximately 30 dB extinction ratio). Employing this laser source sub-Doppler spectroscopy of the acetylene around 1.54 micrometer has been performed. To obtain the necessary saturation intensity (approximately 3.5 W/mm2), the absorbing sample is placed inside a Fabry- Perot cavity with a Finesse of approximately 150. The dispersion signal of the sub-Doppler resonance, useful to stabilize the laser frequency, has been obtained by dithering the Fabry-Perot piezo and employing a lock-in detection scheme.