High-performance, radiation-hard, widely-tunable integrated laser/modulator chip and large-area avalanche photodetectors (APDs) are key components of optical transmitters and receivers that can dramatically lower the barriers to deployment and operation of high capacity in-space optical communication links. Agility Communications develops and manufactures widely-tunable CW sources and transmitters based on chip-scale integration of a Sampled-Grating Distributed Bragg Reflector (SG-DBR) laser with an Electroabsorption or Mach-Zehnder modulator. The performance characteristics of these devices include 40 nm wavelength coverage, multi- Gigabit/sec data rates, low drive voltage, and compatibility with high spectral efficiency and high-sensitivity modulation formats. Agility has licensed low-noise APD structures patented at the University of Texas at Austin. These devices have achieved record-setting noise and gain-bandwidth performance and are ideally suited for space-based, high-bandwidth optical links. During Phase I of this project we will study the effects of proton irradiation for SG-DBR lasers, InGaAsP bulk electroabsorption and electro-optic modulators, and APDs with InAlAs multiplication structure. Based on the results of Phase I, optimum chip design and process technology will be selected for development of small, efficient, radiation-hard integrated optical components in Phase II of the project.