Focused ion beam lithography of multiperiod gratings for a wavelength‐division‐multiplexed transmitter laser array

Wavelength‐division multiplexing with closely spaced multiple wavelengths is of great interest for high‐capacity data transmission. One major and very critical requirement of such a system is the fabrication of a laser array with very small wavelength separations (∼2 nm). In this paper, the design, fabrication, and performance of an integrated eight‐channel system is described. Focused ion beam lithography, with the beam deflection sensitivity modified from its calibrated value, is used to write the critical stepped‐period distributed‐Bragg‐reflector gratings required to provide the tightly controlled multiple laser frequencies. The outputs of the lasers are combined via curved waveguides into a single optical output. © 1995 American Vacuum Society