Photonic Circuits for Broadband, High Dynamic Range Analog RF Applications Navy STTR FY2005 Sol No.: Navy STTR FY2005 Topic No.: N05-T008 Topic Title: Photonic Circuits for Broadband, High Dynamic Range Analog RF Applications Proposal No.: N054-008-0110 Firm: Photonic Systems, Inc. 900 Middlesex Turnpike Building #5 Billerica, Massachusetts 01821 Contact: Gary Betts Phone: (760) 839-8211 Web Site: www.photonicsinc.com Abstract: This proposal describes a linear modulation/demodulation architecture to impart analog photonic links with high dynamic range in wide instantaneous bandwidths, making them suitable for insertion into the RF systems on naval aircraft. This revolutionary architecture is projected to impart a fiber-optic link with an SFDR of > 125 dB�Hz2/3 for instantaneous bandwidths of up to 1 GHz and over an operational bandwidth of 100 MHz - 20 GHz after the completion of technology developments in Phase II of the program. In the 7-month base portion of Phase I, PSI will assemble a benchtop low-frequency version of the link using COTS components and compare its measured SFDR to that predicted by the PSI/UCSD analytical model, and UCSD will complete a design of two InGaAsP/InP integrated circuits that monolithically incorporate all of the optical and electro-optic components in the link's optical transmitter and optical receiver modules. In a subsequent 3-month Option, PSI/UCSD will use the results of the benchtop link measurements to update our analytical model, and use this improved model to design a prototype 100 MHz - 20 GHz link-including the InGaAsP/InP optical transmitter and optical receiver chips in addition to an integrated electronic feedback circuit-for manufacture in Phase II. Benefits: Besides enabling extremely desirable dynamic range performance, the PSI/UCSD RF photonic link architecture imparts additional benefits to an RF signal distribution system: 1) Broad operational bandwidth. Links that are constructed using the revolutionary linear modulation/demodulation architecture proposed herein can route RF signals at frequencies extending from below 100 MHz to above 20 GHz over distances of > 1 km because of the very low attenuation of 1550-nm light in single-mode optical fiber, and there is nothing to cause an out-of-band signal to "mix into" the band. Therefore a notch filter need not be included at the front end, and can instead by inserted after the link and directly before the receiver, if desired, where its loss has a less detrimental effect on the minimum detectable signal. 2) Small size, weight, and power. The optical transmitter module shown in Figure 2 of this proposal is intended to attach directly to an antenna. It is extremely light and can be designed to inhabit a small volume-less than 1 in^3-and requires no dc power whatsoever. The laser and photodetector module that connects to the receiver electronics within the body of a naval aircraft can also be very small-less than 10 in^3-and can consume less than 2 W of dc power. 3) Environmental insensitivity. Compared to coaxial cable, optical fiber has an electrical length that varies much less drastically with temperature. Return