| 摘要 |
<p>An monolithic version of optical multiplexer/demultiplexer with an improved spectral characteristic is provided by two diffraction gratings (20, 21) arranged optically in tandem and with a field stop (71, 107) in the coupling between them, the gratings also being arranged to provide free spectral ranges differing by a factor of at least two, and having a coupling (22) between them that carries over into the second grating information conceming the dispersion afforded by the first grating. The field stop is constituted by a pair of etched troughs (70, 105) arranged in the pattem of an open chevron. The diffraction gratings may be configured as a plurality of optical waveguides extending in side-by-side relationship in a set of arcuate optical paths disposed such that the set of arcuate paths of the optical waveguides of one of the diffration gratings embraces the set of arcuate paths of the optical waveguides of the other diffraction grating. <IMAGE></p> |
