3 Gbps Free Space Optical Link based on Integrated Indium Phosphide Transmitter

Abstract

In the last half century, advances in radio frequency (RF) and microwave technology have paved the way for space communications. Then in 2013, NASA demonstrated a two-way laser link between earth and a satellite in lunar orbit over 239,000 miles at a data rate of 622 Mbps, which is more than six times faster than previous state-of-the-art radio systems deployed to the moon [1]. The free space optical systems can be assembled with commercial-off-the-shelf(COTS) components. However, for deployment on small spacecraft, lower cost, size, weight and power (CSWaP) is required, while still demonstrating high output optical power and power-efficient modulation formats [2]. The indium phosphide (InP) photonic integrated circuit (PIC) platform is attractive for free space links since it enables complex single-chip implementations of advanced transmitters and receivers [3]–[5]. In this work, a free space optical link based on an InP PIC transmitter has been demonstrated. The transmitter is tunable from 1521 nm to 1565 nm, covering the entire C band. Error-free operation was achieved at 3 Gbps for an equivalent link length of 180 m (up to 300 m with forward error correction), and this distance can scale with the use of a high-power amplifier at the output.