Ultrahigh-frequency stabilization of a diode-pumped Nd:YAG laser with a high-power-acceptance photodetector

Shot-noise-limited laser power stabilization with a high-power photodiode array

The output power of a cw Nd:YAG laser was stabilized in a dc-coupled feedback loop with a low-noise multiphotodiode detector and an electro-optic amplitude modulator in the frequency band from 1 Hz to 1 kHz. For the first time, to our knowledge, an independently measured relative power noise of 2.4 x 10(-9) Hz(-1/2) at 10 Hz was achieved, fulfilling the power stability requirements of the Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory) gravitational wave detector.

Near shot-noise-level relative frequency stabilization of a laser-diode-pumped Nd:YVO(4) microchip laser

A laser-diode-pumped Nd:YVO(4) microchip laser was built and actively frequency stabilized relative to a Fabry-Perot cavity with the frequency-modulated sideband technique. The error signal reaches the shot-noise level of 7.4 mHz/√Hz around 1 kHz. Excess intensity noise sets a lower limit of16.5 mHz/√Hz for the relative frequency noise, corresponding to a spectral linewidth of 860 μHz. We discuss the method for reconstructing the actual frequency deviation from the observed error signal.

Accurate measurement of the radius of curvature of a concave mirror and the power dependence in a high-finesse Fabry-Perot interferometer

We describe the accurate measurement of the radius of curvature of a concave mirror in a Fabry-Perot interferometer with a finesse of 78,100. The radius of curvature of the concave mirror is determined by measuring the free spectral range and the transverse-mode range with the frequency response functions. The radii of curvature at two orthogonal (x and y) axes on the mirror surface resulting from the polishing nonisotropy were accurately measured to be r(x) = 1008.46 mm and r(y) = 1006.94 mm, respectively, with an accuracy of 8 × 10(-5). This accuracy is the best to our knowledge. The power dependence of the radii of curvature to the cavity internal intensity at a steady state was measured to be dr(x)/dI(c) = +60 µm/(MW/cm(2)) at the x axis and dr(y)/dI(c) = +47 µm/(MW/cm/(2)) at the y axis to an intensity of 2.1 MW/cm(2).

Vibration transducer using an ultrashort Fabry-Perot cavity

We report here on the development of an optical transducer for mechanical vibration, making use of an ultrashort Fabry-Perot cavity. The noise level measured by a cavity 150 µm long is ~1.3 × 10(-16) m/√Hz at ~1 kHz, which was obtained without a frequency-stabilization system. It was, however, large compared with the shot noise.