• DOI:10.1103/PhysRevA.106.053504
• Corpus ID: 251224252

Self-mixing interference in a thin-slice solid-state laser with few feedback photons per observation period

@article{Otsuka2022SelfmixingII,
  title={Self-mixing interference in a thin-slice solid-state laser with few feedback photons per observation period},
  author={Kenju Otsuka and Seiichi Sudo},
  journal={Physical Review A},
  year={2022}
}

• K. Otsuka, S. Sudo
• Published 31 July 2022
• Physics
• Physical Review A

Formation of a peculiar lasing pattern leading to a TEM 00 -like mode accompanied by a nonzero bright outer-ring emission (namely, a modified TEM 00 mode) was observed in a 300-  m-thick LiNdP 4 O 12 (LNP) laser with reflective flat end mirrors that was pumped with a laser diode whose focused spot size was larger than the lasing beam spot size determined by the thermal lens effect. The photon lifetimes of the laser oscillations were found to be greatly shortened to  p = 6.74 ps as compared with those in pure TEM 00 mode operation, while the fluorescence lifetime was  = 130  s. The formation of the peculiar transverse mode was theoretically treated in terms of the pump-intensity-dependent thermal lens effect, which yields the lasing beam spot sizes in the resultant optical cavity. In addition, transverse spatial hole burning of population inversions due to the preceding transverse eigenmode intensity and the associated anti-guidance of the pure TEM 00 field leading to formation of the TEM 00 with an emergent outer ring emission was shown to appear with increasing pump power through the electric lens (i.e., population lens) effect, in which almost all of the population inversion contributes to lasing with a pronounced effective modal gain. Self-mixing laser Doppler velocimetry (LDV) experiments and numerical simulations revealed that spontaneous emission factors in the peculiar mode oscillations were greatly decreased in comparison with those in pure TEM 00 mode operation. The present thin-slice solid-state laser possessing a large fluorescence-to-photon lifetime and decreased spontaneous emission factor enabled us to detect LDV signals in the regime of few feedback photons per observation period.