TECHNOLOGY AREA(S): Air Platform, Electronics, Information Systems

ACQUISITION PROGRAM: PMA-234 Airborne Electronic Attack Systems

OBJECTIVE: Develop a single-mode multicore fiber optic connector for wideband digital and analog fiber optic links.

DESCRIPTION: Complex military communications, sensing, and surveillance systems require distribution of high fidelity analog and digital signals. Due to their wide bandwidth, low weight, and immunity against electromagnetic interference, analog and digital fiber optic links have attracted ample attention. For analog links, meeting the dynamic range requirements of communication and radar systems has proven to be challenging. In particular, nonlinearities of the electro-optic modulator, photodetectors, and electronic amplifiers have prevented the true potential of analog photonic links to be realized. In addition to dynamic range, link noise figure and connector performance pose other bottlenecks for some wideband applications. For digital links, while significant research has been conducted on improving transceiver packaging and the fault detection and isolation capability of link components, single-mode fiber has had difficulty penetrating the avionics, sensor and electronic warfare aircraft application markets. Single-mode fiber-based analog and digital optical links that meet the stringent performance metrics of a military airborne platform system have remained elusive.� Analog and digital links that incorporate fiber optic built-in test technology also has remained elusive.

In recent years, there has been significant progress in single-mode fiber optic connector performance for airborne platform applications, as well as significant progress in multicore fiber development. Leverage the progress in aerospace single-mode fiber optic connectors and multicore fiber to create a connector that is compatible with multicore fiber.

The envisioned connector should meet the environmental and mechanical requirements described in MIL-PRF-64266 [Ref 2]. The multicore fiber should have two cores separated by a distance that enables low optical loss, high return loss, and low optical crosstalk [Ref 5]. 38-micrometer core-to-core spacing and splicing capability has been reported in the literature, and U.S.-based specialty fiber manufacturers have demonstrated the capability to produce multicore fiber [Ref 5]. This SBIR topic is focused on development of a single-mode multicore fiber connector for two-core-, multicore-, fiber optic-based analog and digital links whereby the two cores are �weakly coupled� per the discussion of multicore fiber in Reference 3. It is anticipated that the connector contemplated under this SBIR topic will accommodate physical contact, angled physical contact, and expanded beam multicore fiber interfaces. The connector is expected to provide low insertion loss, low crosstalk, and high return loss at optical power levels required in modern radiofrequency-over-fiber (RFoF) wideband microwave photonic links operating at the 1,000-nanometer and 1,550-nanometer RFoF wavelength bands.

PHASE I: Develop detailed multicore fiber connector design concepts addressing specifics in the Description and providing low optical insertion loss, high return loss, and low crosstalk in mated multicore fiber connectors. Demonstrate concepts through modeling and simulation of the connector's optical characteristics, and digital and analog link performance. Develop a Phase II plan.

PHASE II: Design, develop, and test two-core multicore fiber optic connector prototypes at 1,550 nanometer wavelength.

PHASE III DUAL USE APPLICATIONS: Finalize and transition the demonstrated product to pre-production engineering prototypes for use in state-of-the-art digital and analog fiber optic links. Commercial sector data centers, local area networks, and telecommunication systems can benefit from the development of multicore fiber connector technology.

REFERENCES:

1. Urick, V.J., Williams, K.J., and McKinney, J.D. "Fundamentals of Microwave Photonics". Wiley Series in Microwave and Optical Engineering, 2015, Kai Chang, Editor. ISBN: 978-1-118-29320-1

2. MIL-PRF-64266. Connectors, Fiber Optic, Circular, Plug and Receptacle Style, Multiple Removable Genderless Termini, Environment Resisting General Specification for, Defense Logistics Agency, Columbus, Ohio.� http://everyspec.com/MIL-PRF/MIL-PRF-030000-79999/MIL-PRF-64266_37947/

3. Saitoh, K. and Matsuo, S. "Multicore fiber technology". Journal of Lightwave Technology, vol 34, no. 1, pp. 55-66, 1 January 2016. http://ieeexplore.ieee.org/document/7214203/

4. Nagase, R., Sakaime, K., Watanabe, K. and Saito, T. "MU-type multicore fiber connector". Proceedings of the 61st International Wire and Cable Symposium, pp. 823-826, 2012. http://www.iwcs.org/polopoly_fs/1.1585132.1417722537!/fileserver/file/313597/filename/17-2.pdf

5. Zhu, B., Taunay, T.F., Yan, M.F., Fini, J.M., Fishteyn, M., Monberg, E.M., and Dimarcello, F.V. "Seven-core multicore fiber transmissions for passive optical networks". Optics Express, vol. 18, no. 11, pp. 11 117-11 122, 24 May 2010.� https://www.osapublishing.org/oe/abstract.cfm?uri=oe-18-11-11117

KEYWORDS: Multicore Fiber; Connector; Crosstalk; Digital; Analog; Avionics