OPTICAL RESONATOR WITH A MONOMODE FIBRE AS RING RESONATOR, AND APPLICATION OF SUCH A RESONATOR

摘要

In systems of optical telecommunications or measurement engineering having ring resonators which are supplied via a directional coupler, it is possible to avoid oppositely directed light waves, i.e. reflections, in an optical fibre. The "free spectral region" (FSR) and the "bandwidth" ( DELTA f) are characteristic of such resonator configurations. It is the object of the invention to make possible the required adjustments for light waves of different spectral width. For this purpose, the fibre resonator is formed as an inherently closed ring (11) made from a polarisation-maintaining monomode fibre (10), which is at the same time incorporated into the resonator-side half (12s) of a fibre directional coupler (12), via which the resonator ring (11) is supplied. A second fibre directional coupler (13) is constructed correspondingly, and serves to tap the resonator ring (11). The free spectral region SFR is determined by the length of the resonator ring (11), and the quality is determined by the attenuation (Fig. 1). Such resonators can be used, e.g., for optical bandpass filters, for multiplexer/demultiplexers and, in particular, as a discriminator for frequency stabilisation of a laser.