Planar Rowland spectrometer for fiber-optic wavelength demultiplexing

A planar Rowland spectrometer was fabricated and characterized as a wavelength demultiplexer for multimode fiber-optic applications. The spectrometer consisted of a planar multimode glass waveguide with two curved end faces and a cylindrical concave grating attached to one of the end faces. Semiconductor lasers with wavelengths between 0.825 and 0.845 microm were used for the measurements. Cross-talk isolation between two adjacent fibers with center-to-center separation of 175 microm (100 A in wavelength difference) was measured to be 18 dB. The device's performance was limited by grating diffraction efficiency, optical aberration , waveguide dispersion, and waveguide losses.