Indium Phosphide Photonic Integrated Circuits for Free Space Optical Links

An indium phosphide (InP)-based photonic integrated circuit (PIC) transmitter for free space optical communications was demonstrated. The transmitter consists of a sampled grating distributed Bragg reflector (SGDBR) laser, a high-speed semiconductor optical amplifier (SOA), a Mach-Zehnder modulator, and a high-power output booster SOA. The SGDBR laser tunes from 1521 to 1565 nm with >45 dB side mode suppression ratio. The InP PIC was also incorporated into a free space optical link to demonstrate the potential for low cost, size, weight, and power. Error-free operation was achieved at 3 Gb/s for an equivalent link length of 180 m (up to 300 m with forward error correction).