Narrow-line-width diode laser with a high-Q microsphere resonator

A new modification of external optical feedback OFB was used to narrow the line of a diode laser DL . A 'whispering . gallery' WG mode of a high- Q microsphere was excited by means of frustrated total internal reflection while the feedback for optical locking of the laser was provided by the intracavity Rayleigh backscattering. The ; 600 MHz beatnote of the two laser diodes optically locked to a pair of orthogonally polarized modes of the same microresonator had the indicated spectral width of 20 kHz, and the stability of 2 = 10 y6 over averaging time of 10 s. The feasibility of miniature sub-kHz-line width