Frequency stabilization of frequency-doubled Nd:YAG lasers at 532 nm by frequency modulation spectroscopy technique

Investigation of Short-term Amplitude and Frequency Fluctuations of Lasers for Interferometry

“…The linewidth of the laser is below the 10 kHz level (integration time 0.1-1 s). Both L1(L2) and L3 are primarily intended for saturated subdoppler spectroscopy in iodine vapor at 532 nm wavelength and are designed to operate as laser optical frequency standards [32][33][34][35][36][37][38] with long-term frequency stability at 1*10 -14 level. L4 laser is simple DPSSL (diode pumped solid state laser) with alignment-free monolithic resonator equipped with slow thermal frequency tuning option which allows the linear absorption spectroscopy frequency stabilization technique.…”

“…This frequency stability is fully sufficient for measurements that are done on air conditions -the influence of the refractive index of air fluctuations is in the order of 10 -7 or can be compensated up to this level [23][24][25][26][27][28][29][30][31]. Next, the relative frequency stability of frequency doubled Nd:YAGs stabilized by some more sophisticated technique like saturated subdoppler spectroscopy in iodine vapor can be in the range close to the 10 -14 level for 100 s integration times [32][33][34][35][36][37][38]. Furthermore, not only long-term but also short-term frequency stability is important, especially in cases of high-speed interferometric systems.…”

Comparison of Molecular Iodine Spectral Properties at 514.7 and 532 nm Wavelengths

“…The first part of the arrangement with the Cell1 uses the third harmonic inline spectroscopy detection technique for the frequency stabilization of the laser to a selected molecular iodine hyperfine component [7,[10][11][12]15]. This laser is equipped with a PZT for the tuning of the cavity length, which is used for modulation of its optical frequency.…”

“…The a 10 hyperfine component of the P46(44-0) absorption line was studied with a special care under different experimental conditions. This hyperfine component seems to perform the most promising shape and linewidth.…”

“…Solid-state, frequency doubled Nd:YAG lasers stabilized by subdoppler saturation spectroscopy to hyperfine transitions in molecular iodine are used in metrological laboratories as stabilized lasers and represent the most stable optical references for interferometry and other applications in fundamental metrology. These lasers stabilized by saturation spectroscopy can achieve long-term frequency stability better than 1*10 -14 for an integration time of 100 s, which means a more than two orders better result in comparison to traditionally used He-Ne-I 2 stabilized standards [6][7][8][9][10][11][12][13][14][15][16]. The short-term frequency noise of these lasers is also lower [17][18][19][20].…”