Integrated optical wavelength demultiplexer

Abstract

An optical wavelength demultiplexer is fabricated as an integral part of an integrated circuit chip. A waveguide in a common substrate having a chirped diffraction grating receives a number of wavelengths of optically modulated data from a single mode fiber. The wavelengths are diffracted from the plane of the lines of the grating into discrete beams angles through the substrate and impinge on appropriately located photodetectors. Signals provided by the detectors are fed to and processed by other integrated circuitry also contained on the chip. The common transparent substrate such as fused silica, glass, sapphire, lithium niobate or lithium tantalate mount semiconductor films of Si, Ge, GaAs or quanternary alloys that have the detectors and other integrated circuitry that are created by conventional CVD techniques. The waveguide and appropriate chirp grating are formed by established deposition and photolithographic procedures ot assure the separation of as many as fifty discrete beams of as many different wavelengths and their projection onto a like number of photodetectors to provide for a heretofore unattainable degree of optical wavelength demultiplexing.