Design of frequency-difference stabilizing system for two-cavity dual-frequency Nd:YAG laser using quadrature-demodulated Pound–Drever–Hall method

Advances of Research on Dual-Frequency Solid-State Lasers for Synthetic-Wave Absolute-Distance Interferometry

“…In 2022, our group reported a frequency-difference-stabilizing system for the diode-pumped TCDFL at 1064 nm using a double-modulator QD-PDH frequency-stabilizing method [ 43 ], as shown in Figure 39 , which included two sets of QD-PDH frequency-stabilizing subsystems (see parts II and III) that shared the same F-P cavity as the frequency reference, and the magnitude of the frequency difference was required to be an integer number representing times of the free spectral range (FSR) of the referenced F-P cavity.…”

“… Schematic diagram of the frequency-difference-stabilizing system for the TCDFL using the double-modulator QD-PDH frequency-stabilizing method [ 43 ]. LD: laser diode; OF: optical fiber; L: lens; PBS: polarizing beam splitter; FP: F-P etalon; OC: output coupler; PZT: piezoelectric transducer; M: mirror; ISO: optical isolator; P: polarizer; EOM: electro-optic modulator; DDS: direct digital synthesizer; A: amplifier; EOM-DR: EOM driver; QWP: quarter-wave plate; BS: beam splitter; F-P: F-P reference cavity; PD: photodetector; I/V: current-to-voltage; FSA: frequency-selective amplifier; QDU: quadrature-demodulated unit; D/A: digital-to-analog; PZT-DR: PZT driver.…”

“…Many experts and scholars worldwide have investigated the oscillating principles and key technologies of dual-frequency solid-state lasers with tunable and large frequency difference since 2000 [ 14 , 15 , 16 , 17 , 18 , 19 ], and they have successfully developed a series of new dual-frequency solid-state lasers, such as the birefringent dual-frequency solid-state laser [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ], the biaxial dual-frequency solid-state laser [ 31 , 32 ], the two-cavity dual-frequency Nd:YAG laser (TCDFL) [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ], and so on. Especially in the recent years, our research group has made important progresses in the research and development of the TCDFL and its quadrature-demodulated Pound–Drever–Hall (QD-PDH) frequency-stabilizing technology [ 41 , 42 ], and the QD-PDH frequency-stabilizing method has been applied to the frequency-difference stabilization of the TCDFL with a frequency difference of 24 GHz at 1064 nm [ 43 , 44 ]. This frequency-difference-stabilized TCDFL at 1064 nm has been successfully used as the light source for a synthetic-wave absolute-distance interferometric system [ 45 ].…”

Design of frequency-difference stabilizing system for two-cavity dual-frequency Nd:YAG laser using single-modulator quadrature-demodulated Pound–Drever–Hall method

“…According to the Ref. 20, the orthogonally and linearly polarized dual-frequency laser beams output simultaneously from linear and right-angle cavities are p- and s-polarized single-frequency laser (SFL) beams, respectively. Therefore, a coaxially propagating beam of the orthogonally and linearly polarized dual-frequency laser can be phase-modulated using a single EOM, provided that both polarization directions of the incident dual-frequency laser beam parallel to the inductive principal axes of the electro-optic crystal, respectively.…”

“…The experimental results had shown that the resonant frequency of the FP cavity could track the laser frequency in real time. To stabilize the frequency difference of the two-cavity dual-frequency Nd:YAG laser at 1064 nm based on the polarization splitting principle, 19 our research group had further designed and investigated a quadrature-demodulated PDH (QD-PDH) frequency-difference stabilizing system, 20 in which the orthogonally and linearly polarized dual-frequency laser could be phase-modulated by double electro-optic modulators (EOMs). And the two frequencies of the dual-frequency laser had been simultaneously stabilized to the two different resonant frequencies of the FP reference cavity, the frequency-difference stability of better than 4.2×10−7 had been experimentally obtained.…”