Summary: IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 10, NO. 6, JUNE 1998 839
Multiwavelength Diffraction and Apodization
Using Binary Superimposed Gratings
Ivan A. Avrutsky, Martin Fay, Student Member, IEEE, and J. M. Xu, Senior Member, IEEE
Abstract--The binary superimposed grating (BSG), consisting
of equal-size segments of two possible values of refractive index
and capable of effecting multiwavelength reflection, offers ease
of fabrication and great versatility in guided-wave wavelength-
division-multiplexing (WDM) applications. We present an ana-
lytical formula for the coupling strength of a BSG as a function
of segment size, and verify it with numerical transfer matrix
simulations of the grating reflectance spectra. Perfect agreement
is found for a single grating, and values 10%­12% less than pre-
dicted for 2­11 superimposed gratings. Subdividing the grating
into sections of grouped segments permits step-like apodization,
while maintaining binary index and base segment size. Sidemode
suppression ratios (SMSR's) of 27 and 16 dB are computed for
single-peak and 11-peak BSG's respectively.
Index Terms-- Apodization, diffraction gratings, distributed
Bragg reflector (DBR) lasers, laser resonators, wavelength-

Source: Avrutsky, Ivan - Department of Electrical and Computer Engineering, Wayne State University

Collections: Engineering