Orthogonally polarized dual frequency lasers and applications in self-sensing metrology

Abstract

The traditional Zeeman laser (Z-laser) outputs a frequency difference generally smaller than 2MHz, which has limited its applications. An orthogonally polarized laser is capable of outputting two frequencies with a 90-angle between their polarization directions. The difference between the two frequencies may range from 1MHz to 1GHz, determined by the birefringence within the resonance cavity of the laser. Because it is easy to adjust the frequency difference and to detect the intensities of the two frequencies separately, a number of unknown characteristics are observed in cavity tuning and optical feedback. These properties have turned and will turn into the working principles of self-sensing metrology instruments. That is to say that an orthogonally polarized laser, in addition to serve as a light source of a dual frequency laser, may be changed into a metrological apparatus. It has selfsensing ability, namely laser itself is just the instrument, e.g. nanometer displacement based on laser cavity tuning or feedback effects, retardation of a wave-plate based on frequency splitting or feedback effects, and non-contact high resolution laser feedback interferometer.

Orthogonally dual-polarization passively mode-locking operation of Nd:La0.25Gd0.75VO4 crystal

“…Lasers with orthogonal polarization states are important in scientific research and many practical applications such as laser interferometry and precision metrology [1,2]. Some crystals could generate polarized laser emission automatically because of the intrinsic birefringence of the host crystal, such as the Nd:YVO 4 or Nd:YLF crystals.…”

Monolithic dual-polarization self-mode-locked Nd:YAG 946-nm lasers: controlling beat frequency and observation of temporal chaos

“…Orthogonally polarized dual-frequency (OPDF) lasers are attractive for many applications, such as optical navigation, military purpose, medical surgery, material processing and highresolution measurement [1][2][3][4][5][6][7]. One typical method for generating the OPDF laser is to insert a birefringent element into the laser cavity to split the laser frequency between two orthogonal states [7][8][9].…”

Dual-comb self-mode-locked monolithic Yb:KGW laser with orthogonal polarizations

“…Various Nd-doped gain media have been widely employed to generate dual-wavelength laser sources [1][2][3][4][5][6] for the applications on laser interferometry, precision measurement, medical instrumentation, holographic microscopy, and differential absorption lidar [7][8][9]. In recent years, dual-comb mode-locked lasers with slightly different pulse repetition rates have also started to attract much attention due to the applications on laser spectroscopy [10][11][12] and asynchronous optical sampling for pump-probe measurements without mechanical delay [13].…”