N221-045 TITLE: Fiber Optic Cable for Radio Frequency Over Fiber Links

OUSD (R&E) MODERNIZATION PRIORITY: Networked C3

TECHNOLOGY AREA(S): Electronics

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a military fiber optic cable for analog optical communication operating at no less than 45 GHz in air and sea platform fiber optic links.

DESCRIPTION: Current military shipboard and aerospace platform communications and electronic warfare systems require ever-increasing bandwidths while simultaneously demanding reductions in space, weight, and power (SWaP). The replacement of shielded twisted pair (STP) wire and coaxial cable with earlier generation length-bandwidth product multimode optical fiber has given increased immunity to electromagnetic interference, bandwidth, and throughput, and a reduction in size and weight. To address the emerging needs of radio frequency (RF), microwave and millimeter-wave applications to route and process increasingly high-frequency signals, photonics, and fiber optics play an important role in future military shipboard and aerospace platform applications. Polarization modulation with interferometric detection and balanced intensity modulation with direct detection (IMDD) provide advantages over conventional IMDD links.

In order to realize polarization modulation and balanced IMDD photonic link technology on military platforms, polarization maintaining and multi/dual-core fiber optic cable development and qualification is required. Shipboard and aerospace optical fiber and fiber optic cable share military specifications. MIL-PRF-49291/11 [Ref 1] describes modern examples of single mode optical fiber for shipboard and aerospace application. MIL-PRF-49291/11 specifies 8.2 to 9.5 �m mode field diameter (at 1,310 nm) and from 9.4 to 10.5 �m mode field diameter (at 1,550 nm) single mode fiber. Two operating temperature ranges are specified (-46 to +85�C and �55 to +165�C). Maximum macro-bend attenuation at 1,550 nm is 0.03 dB for ten turns around a 30 mm diameter mandrel. MIL-PRF-49291/7D describes modern examples of single-mode optical fiber for shipboard and terrestrial applications.

MIL-PRF-85045/16 [Ref 2] and MIL-PRF-85045/31 [Ref 3] are modern examples of fiber optic cable for shipboard and aerospace application, respectively. Two cable operating temperature ranges are specified (-40 to +85�C and �55 to +165�C). Short-term minimum bend diameter is eight times the cable outer diameter and long-term minimum bend diameter is 16 times the outer diameter. The maximum cable attenuation rate for cable with 9/125 �m single mode fiber is 1.0 dB/km at 1,310 nm, 1.0 dB/km at 1,383 nm, and 0.75 dB/km at 1,550 nm.

Shipboard and aerospace military installation requirements are well defined. No military specifications address polarization maintaining and dual-core optical fiber cable types. Innovation is needed to demonstrate military qualifiable polarization maintaining and dual-core fiber optic cables. One aspect of this research is to specify related optical fiber design and qualification test considerations relating to polarization maintaining and dual-core fibers. Another aspect of this research is to compare conventional single-mode fiber and fiber optic cable, as specified in MIL-PRF-49291 and MIL-PRF-85045, to polarization maintaining and dual core fiber optic cables with respect to military specification and application to polarization modulation and balanced IMDD photonic links. The testing will be defined in the MIl-SPEC, which is an output of proposal and early phase of effort. Testing to be done by SBIR awardee. Using data from this research effort, the Navy seeks to create new fiber and cable specifications and update MIL-STD-1678, MIL-PRF-85045, and MIL-PRF-49291.

PHASE I: Develop a concept for polarization maintaining and dual-core fiber optic cables for military and commercial applications. Demonstrate the feasibility of fiber optic cable designs, showing the path to meeting Phase II goals. Design polarization maintaining fiber optic cable prototypes that are compatible with distributed feedback laser outputs and high-speed electro-optic modulator inputs. Design dual-core fiber optic cable prototypes that are compatible with balanced photodetector inputs. Demonstrate the feasibility of the concept to meet the described parameters listed in the Description through modeling, simulation, and analysis. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.

PHASE II: Develop and deliver a prototype fiber optic cable design optimized from Phase I. Build the fiber optic cables to meet performance requirements described in the Description and draft specification planned for publication in MIL-PRF-85045 and MIL-PRF-49291. Test the fiber optic cables. If necessary, perform root-cause analysis and remediate fiber optic cable failures. Deliver fiber optic cables to the Navy.

PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to Navy use by verifying and validating the cable performance for transition to military and commercial fiber optic platforms. Commercial sector telecommunication systems, fiber optic networks, and data centers optical networks could benefit from the development of Polarization Maintaining and Dual-Core Fiber.

REFERENCES:

1. DLA Land and Maritime. (2019, July 17). MIL-PRF-49291/11B: Fiber, optical, type II, class 5, size II, composition A, wavelength D, radiation resistant, enhanced performance characteristics (Metric). Department of Defense. https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=276804.
2. Naval Sea Systems Command. (2014, June 17). MIL-PRF-85045/16C: Cable, fiber optic, single (one) fiber, cable configuration type 2 (OFCC), tight buffer, cable class SM and MM. Department of Defense. https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=106883.
3. (2019, July 17). MIL-PRF-85045/31A: General specification for cable, fiber optic. Department of Defense. https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=276840.
4. Diehl, J., Nickel, D., Hastings, A., Singley, J., McKinney, J., & Beranek, M. (2019, November). Measurements and discussion of a balanced photonic link utilizing dual-core optical fiber. In 2019 IEEE Avionic and Vehicle Fiber-Optics and Photonics Conference (pp.1�2). IEEE. https://doi.org/10.1109/AVFOP.2019.8908161.
5. Saitoh, K., & Matsuo, S. (2016). Multicore fiber technology. Journal of Lightwave Technology, 34(1), 55-66. https://www.osapublishing.org/jlt/abstract.cfm?uri=jlt-34-1-55.
6. Abe, Y., Shikama, K., & Asakawa, S. (2017). Multi-core fiber connector technology for low-loss physical-contact connection. NTT Tech. Rev., 15(6), 1-6. https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr201706fa6.pdf&mode=show.

KEYWORDS: Multicore Fiber; Polarization Maintaining Fiber; Fiber Optic Cable; Radio frequency; RF; Single Mode Fiber; IMDD photonic link technology