A fringe locking phenomenon in a two beam interferometer using a semiconductor laser subject to optical feedback has been observed, whose injection current is modulated. When a path difference of the interferometer is sufficient, fringes taken by a CCD camera are seen to be stationary and the rms fluctuations of fringe phase is reduced to as low as 0.2 (pi) radians from more than 9 (pi) radians that is observed without the optical feedback. The rms phase fluctuation is independent of frequency and amplitude of the current modulation. The fringe locking has also been observed in the presence of both injection current modulation and PZT mirror vibration of the interferometer. A theoretical analysis has been performed that explains the observed phenomenon. It has been shown that the wavelength change due to injection current is controlled by the interferometer. The dependence of wavelength change on the injection current variation is calculated using a model of coupled resonators consisting of the laser cavity and the interferometer. The fringe phase change caused by modulation of injection current is derived from it. The calculated phase fluctuation agrees well with those observed in experiments.
[1]
Takamasa Suzuki,et al.
Sinusoidal phase modulating laser diode interferometer with feedback control system to eliminate external disturbance
,
1990
.
[2]
Ichirou Yamaguchi,et al.
Active phase‐shifting interferometers for shape and deformation measurements
,
1996
.
[3]
T C Strand,et al.
Laser diode feedback interferometer for stabilization and displacement measurements.
,
1987,
Applied optics.
[4]
Active Phase-Shifting Interferometer Using Current Modulation of a Laser Diode
,
1996
.
[5]
Ichirou Yamaguchi,et al.
Fringe locking in a laser diode interferometer by optical feedback
,
1998,
Optics & Photonics.
[6]
Junji Ohtsubo,et al.
Dynamics and chaos stabilization of semiconductor lasers with optical feedback from an interferometer
,
1997
.