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Gallium Arsenide Based 1-Micrometer Integrated Analog Transmitter


Current airborne military communications and electronic warfare systems require ever increasing bandwidths while simultaneously requiring reductions in space, weight and power (SWaP). The replacement of the coaxial cable used in various onboard RF/analog applications with RF/analog fiber optic links will provide increased immunity to electromagnetic interference, reduction in size and weight, and an increase in bandwidth. However it requires the development of high performance, high linearity optoelectronic components that can meet extended temperature range requirements (-40 to 100 degrees Celsius (C)). Additionally, avionic platforms pose stringent requirements on the SWaP consumption of components such as optical transmitters for avionic fiber communications applications. To meet these requirements, new optical component technology will need to be developed. Current analog optical transmitter technology typically consists of discrete lasers and modulators operating at 1550 nanometers (nm), with a requirement for active cooling for operation in avionic environments. To meet avionic requirements, the transmitter should integrate laser and modulator into a compact uncooled package that can maintain performance over full avionic temperature range. It is envisioned that a Gallium Arsenide (GaAs) based transmitter at approximately 1 micrometer wavelength can meet this requirement. One (1) micrometer GaAs optical sources can operate over an extended temperature range (>100 degrees C) at high efficiency (up to ~60%). This is currently not possible at 1550nm. The desired optical component is a GaAs-based integrated analog transmitter (laser and high-efficiency modulator), with an integrated optical source with low relative intensity noise (RIN) (<-160dBc/Hz), 100 milliwatt (mW) output power, uncooled operation over a minimum temperature range of -40 to +100 degrees C, and an integrated optical intensity modulator with low V-pi (<2V), packaged in a ruggedized package that has a height less than or equal to 5 mm, and a volume of <2.5 cubic centimeters. The packaged transmitter must perform over the specified temperature range and maintain hermeticity and optical alignment upon exposure to typical Navy air platform vibration, humidity, thermal shock, mechanical shock, and temperature cycling environments [4]. PHASE I: Develop and analyze a new design and packaging approach for an uncooled 1 micrometer optical transmitter that meets the requirements outlined in the Description section. Develop fabrication process, packaging approach, and test plan. Demonstrate feasibility of the optical transmitter with a supporting proof of principle bench top experiment. PHASE II: Optimize Phase I transmitter and package design and develop a prototype. Test prototype transmitter to meet design specifications in a Navy air platform representative of a relevant application environment, which can include unpressurized wingtip or landing gear wheel well (with no environmental control) to an avionics bay (with environmental control). The prototype transmitter should be tested in an RF photonic link over temperature with the objective performance levels reached. Demonstrate a prototype fully packaged transmitter for direct insertion into analog fiber optic links. PHASE III: Perform extensive operational reliability and durability testing, as well as optimize manufacturing capabilities. Transition the demonstrated technology to Naval Aviation platforms and interested commercial applications.
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