Published/Posted: February 1, 1997
Authors: Murphy, T. E.Abstract: The unavoidable presence of noise in optical communications systems makes it necessary to use filters in practical optical receivers. Noise, especially amplified spontaneous emission noise from optical amplifiers, is what ultimately limits the sensitivity of an optical communications system. This thesis describes an optical matched filter which operates on the principle of Bragg reflection from an integrated grating structure. A matched filter is predicted to yield the highest possible signal to noise ratio, which would allow receivers to more closely approach the theoretical limit in receiver sensitivity. We analyze the predicted behavior of the matched filter device, and present a complete description of the device design, including coupled mode theory, insertion loss minimization, and calculation of fabrication tolerances. We describe a fabrication process which addresses some of the unique nanolithography challenges associated with the device, and present some fabricated structures which demonstrate the feasibility of this process.
T. E. Murphy, "Integrated Optical Grating-Based Matched Filters for Fiber-Optic Communications", MS Electrical Engineering and Computer Science, Massachusetts Institute of Technology (1997)