SELECTIVE REGROWTH OF A WIDE-BANDWIDTH 1.3 MU-M INTEGRATED LOSSLESS TAP AND OPTICAL PREAMPLIFIER

We report the first monolithically integrated wide-bandwidth lossless tap-that is, an optical semiconductor amplifier followed by a colinear reverse-biased waveguiding photodetector with fiber-coupled input and output. The integration was achieved by using, for the first time, of f-axis selective epitaxial growth of ridge waveguides on a patterned d ielectric layer. The tilted facets produced by the off-axis growth, al ong with photodetector absorption, serve to reduce the effective facet reflectivity to -36 dB without any anti reflection coating. By adjust ing the length of the absorbing photodetector section, part or all of the amplified light may be absorbed, allowing the device to function r espectively as a lossless tap or an optical preamplifier. A lossless t ap with an electrical bandwidth of 7 GHz, a responsivity of 26 A/W, an d a fiber-to-fiber gain of 3 dB is shown to have a receiver sensitivit y of -22 dBm at 3 Gb/s.