Vv. Vasilev et al., HIGH-COHERENCE DIODE-LASER WITH OPTICAL F EEDBACK VIA A MICROCAVITY WITH WHISPERING-GALLERY MODES, Kvantovaa elektronika, 23(8), 1996, pp. 675-676
Narrowing of the linewidth of a diode laser was achieved by an externa
l high-Q microcavity, which was a fused silica sphere 370 mu m in diam
eter. Coupling of the radiation in and out, and matching to a 'whisper
ing gallery' mode of this sphere, were ensured by the method of frustr
ated total internal reflection. Optical feedback was provided by the R
ayleigh scattering. The width of the beat-note spectra of the investig
ated and reference lasers did not exceed 100 kHz.