Optical multiplexter/demultiplexer

摘要

PCT No. PCT/GB97/02051 Sec. 371 Date Nov. 16, 1998 Sec. 102(e) Date Nov. 16, 1998 PCT Filed Jul. 30, 1997 PCT Pub. No. WO98/04944 PCT Pub. Date Feb. 5, 1998An optical multiplexer/demultiplexer with an improved spectral characteristic is provided by two diffraction gratings (61, 60) arranged optically in tandem, the gratings being arranged to provide free spectral ranges differing by a factor of at least two, and having a coupling between them that carries over into the second grating information concerning the dispersion afforded by the first grating.