TECHNOLOGY AREAS: Air Platform, Sensors, Electronics, Battlespace, Space Platforms

ACQUISITION PROGRAM: PMA-234, A6/EA6-Prowler

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: Develop a highly integrated dual output analog fiber optic transmitter for high bandwidth, high dynamic range, low power dissipation, analog RF communications capable of surviving in the harsh military aerospace environment.

DESCRIPTION: Aerospace communications has a large number of analog RF system requirements, ranging from electronic warfare (EW) and sensor systems to radar and communications signals, which could benefit from inherent performance properties of optical fiber. Current photonic technology for implementing RF transmission over optical fiber uses discrete components that are optimized for signal integrity performance but are not amenable for use on aircraft due to size, power, and reliability limits. Much progress has been made in the development of integrated photonic chips for fiber optic data communications but little work has been done optimizing integrated photonic chips for analog transmission. Additionally, new devices and materials have been developed such as electro optic polymers and silicon photonics whose benefits to component application are still untested. In order to meet the needs of military avionics, we seek an innovative approach in laser transmitter technology to realize acceptable size, weight and power (SWAP) metrics to fulfill the aerospace analog communications needs. Operation over the International Telecommunications Union (ITU) wavelength grid and ability to be overlaid on a wavelength division multiplexed (WDM) network are also of potential interest.

The "holy grail" of optical communications is to be able to replace current, heavy, difficult to install, hard to maintain, Electro Magnetic Interference (EMI) susceptible copper based RF links (such as rigid coax or specifically tuned cables) with light, flexible, high bandwidth, EMI immune optical fiber cables. High bandwidth and high dynamic range analog photonic links have been demonstrated in the laboratory. However, they fail to provide acceptable SWAP to establish an adequate value proposition for aerospace application. Additionally, these devices can not survive in the harsh aerospace environment (e.g. a wide temperature range exceeding -40 to +100 C and harsh shock and vibration). A number of integrated technologies have been developed under miscellaneous development programs. The objective of this topic is to design and develop an enabling component utilizing the optimum set of technologies to provide these capabilities with the lowest SWAP.

The diversity of analog RF systems in defense and naval aircraft in particular makes it important that candidate photonic circuit concepts be adaptable to a variety of specifications, however, spurious-free dynamic ranges exceeding 120dB/Hz2/3 with instantaneous bandwidths up to and exceeding 1GHz for operational frequencies from sub-100MHz to 20GHz would be expected to meet many of the most demanding applications. In addition, photonic circuit concepts with the potential for operating in a WDM network and covering significant portions of the operational frequency band with a common and/or easily adaptable hardware are desired.

Desired technical parameters to be achieved are:
1. Size: 40mm x 20 mm x 5 mm (height)
2. Power Max: 1W
3. Environmental: -40C to +100C; 6grms
4. Temperature Cycle Qualification: 1000
5. Frequency Range: 20 MHz to 1GHz (minimum): 20 GHz (Objective)
6. Single Wavelength User Specified: 1545 -1565 nm
7. Spur Free Dynamic Range Threshold > 120 dB/Hz2/3
8. Line width (FWHM(Äë) (-3dB fullwidth) (MHz): < 0.75
9. RIN (20~20000MHz): < -160 dB/Hz
10. Side Mode Suppression Ratio: > 45 dB
11. Hermetic Packaged per MIL-STD-883
12. Dual Output Fiber Coupled Output Power: 150 mW per Fiber
13. Output Fiber: Single Mode Fiber (Mode Field Diameter: 5-10 um)
14. BIT: Yes
15. Removable pigtail: Yes

PHASE I: Develop an innovative design approach, demonstrate feasibility and evaluate the proposed technology, with respect to stated performance objectives for avionics application. Metrics include low SWAP, high bandwidth, high dynamic range, ability to survive the harsh military aerospace environment, and potential for wavelength selection leading towards being carried over a WDM network.

PHASE II: Design, fabricate, package, and test a prototype of the highly integrated, wide dynamic range, low SWAP, analog RF laser transmitter that satisfies form, fit, function, performance, and stringent military environmental requirements (see reference 3 and 4 for details).

PHASE III: Complete final development, testing, and transition the optical technology to avionic platforms to optically carry analog transmissions such as EW signals and radar for Naval application.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: An underlining objective of this topic is to develop an innovation integration strategy utilizing the building blocks developed under numerous other development programs. If successful, an innovative integration strategy will be developed which will both meet the Navy's SWAP requirements, as well as provide the scales of economy from increased integration. These economies of scale will then be available for creative entrepreneurs to utilize to develop profitable commercial derivatives. The commercial market utilizes analog optical transmission as well as the DoD. However, their bandwidth and dynamic range requirements are much less stringent than the military needs, not to mention the challenges of surviving in the harsh military aerospace environment and a tolerance for a much larger SWAP penalty. The military market has numerous DoD specific specialty analog applications which are driving the demanding requirements outlined in this topic. Consequently, the specific products designed for the military may not be directly viable for a consumer market. However, the underlying integration strategies should provide many years of commercial derivatives.

REFERENCES:
1. Recent Breakthroughs in RF Photonics for Radar Systems, Garenaux, K.; Merlet, T.; Alouini, M.; Lopez, J.; Vodjdani, N.; Boula-Picard, R., Fourdin, C. Chazelas, J.; Thales Air Defence, Aerospace and Electronic Systems Magazine, IEEE Publication Date: Feb. 2007 , Volume: 22 , Issue: 2 , page(s): 3 - 8, ISSN: 0885-8985.

2. RF Photonics - Why Should Defense Take Notice? Zach, S. Singer, L.; Wales Ltd., Israel, Electrical and Electronics Engineers in Israel, 2006 IEEE 24th Convention Publication Date: Nov. 2006, page(s): 408 - 412,ISBN: 1-4244-0230-1.

3. RTCA DO160 F - Environmental Conditions and Test Procedures for Airborne Equipment, 2007-12-06; www.RTCA.org.

4. McDermott, B.G.; Beranek, M.W.; Hackert, M.J.; "Fiber Optic Cable Assembly Specification Checklist for Avionics Applications" Avionics Fiber-Optics and Photonics, 2006 IEEE Conference; Page(s):80 - 81.

5. Y.-C. Hung, B. Bortnik, H. Fetterman, R. Forber, W. Wang, "Suppressed Carrier Optical Transmitter with Intracavity Modulation for Coherent Analog Optical Links," Optical Fiber Conference, 2007.

6. Novak, Dalma; Clark, Thomas R.; "Broadband Adaptive Feedforward Photonic Linearization for High Dynamic Range Signal Remoting;" Military Communications Conference, 2007. MILCOM 2007. IEEE.

KEYWORDS: RF photonics; Laser; fiber optics; analog optical communications; microwave photonics; networking

** TOPIC AUTHOR (TPOC) **

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