A significant reduction of propagation losses in InGaAsP-InP buried-stripe waveguides by hydrogenation
ABSTRACT We show here that the high propagation losses often measured at /spl sim/1.56 /spl mu/m in InGaAsP-InP buried-ridge stripe waveguides can be significantly brought down by implementing hydrogenation (exposure to deuterium plasma) as the last step to device termination. For example, losses as high as /spl sim/30 dB/cm measured in conventional as-processed structures have dropped down after hydrogenation to typically 4-5 dB/cm. This improved loss value is totally compatible for the realization of passive sections in photonic circuits. We further present preliminary data describing the good thermal stability of these propagation losses in post-hydrogenated structures.
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ABSTRACT: We present the design, fabrication, and results from the first monolithically integrated optical phase-locked loop (OPLL) photonic integrated circuit (PIC) suitable for a variety of homodyne and offset phase locking applications. This InP-based PIC contains two sampled-grating distributed reflector (SG-DBR) lasers, semiconductor optical amplifiers (SOAs), phase modulators, balanced photodetectors, and multimode interference (MMI)-couplers and splitters. The SG-DBR lasers have more than 5 THz of frequency tuning range and can generate a coherent beat for a wide spectrum of frequencies. In addition, the SG-DBR lasers have large tuning sensitivities and do not exhibit any phase inversion over the frequency modulation bandwidths making them ideal for use as current controlled oscillators in feedback loops. These SG-DBR lasers have wide linewidths and require high feedback loop bandwidths in order to be used in OPLLs. This is made possible using photonic integration which provides low cost, easy to package compact loops with low feedback latencies. In this paper, we present two experiments to demonstrate proof-of-concept operation of the OPLL-PIC: homodyne locking and offset locking of the SG-DBR lasers.Journal of Lightwave Technology 03/2010; · 2.78 Impact Factor