High Speed, Watt Class Multi-access Modulators for Airborne and Spaceborne Communications

ABSTRACT: In order to achieve high data transmission rates (>40Gbps), it is necessary to use external modulators as direct diode modulation can be limited by chirping, parasitics or microwave effects. Traditional amplitude modulation is done with Mach Zehnder Interferometers or directional couplers. Unfortunately, this technology is not multi-access compatible without the introduction of multiplexing elements which add Size, Weight and Power consumption (SWaP) to the aircraft budget. An alternative approach is a serially transmitted, parallel encoding system based on an innovative multi-element modulator. In this Air Force Phase I effort, the feasibility of fabricating Watt class multi-access compatible waveguide modulators will be established. The proposed device will withstand high optical power and have a significantly higher rf modulation figure-of-merit than conventional waveguide based modulators. This parallel optical transmitter module suitable for satellite communications directly meets the needs of Air Force programs as called for in AF103-096 TITLE: High-Efficiency Optical Transmitter Module. BENEFIT: A broad range of communication applications will be affected by the availability of higher speed, higher power modulators. Applications include land-based as well as airborne and spaceborne use. Initially, the proposed modulator will address the DoD"s need for laser communications with lower terminal size, weight, and power. Next, free space communications will benefit directly as the near IR wavelengths most beneficial for earth based free space communications can be utilized at relatively high powers, not currently available with lithium niobate modulators. Further, the high figure of merit, simplicity of design, and high power handling will offer improvements for communications across a broader wavelength range than currently offered by lithium niobate modulators