Title :
An Optical Phase-Locked Loop Photonic Integrated Circuit
Author :
Ristic, Sasa ; Bhardwaj, Ashish ; Rodwell, Mark J. ; Coldren, Larry A. ; Johansson, Leif A.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of California, Santa Barbara, Santa Barbara, CA, USA
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.
Keywords :
III-V semiconductors; distributed Bragg reflectors; indium compounds; integrated optics; monolithic integrated circuits; optical beam splitters; optical couplers; optical fabrication; optical modulation; optical phase locked loops; photodetectors; semiconductor optical amplifiers; DBR; SOA; feedback loops; frequency tuning; homodyne locking; monolithically integrated circuit; multimode interference couplers; optical phase-locked loop; optical splitters; phase modulators; photodetectors; photonic integrated circuit; sampled-grating distributed reflector; semiconductor optical amplifiers; Coherent optical communications; integrated optoelectronics; optical phase-locked loops (OPLLs); tunable semiconductor lasers;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2009.2030341