TECHNOLOGY AREA(S): Electronics, Materials/Processes, Sensors

ACQUISITION PROGRAM: Strategic Systems Programs ACAT IC

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 section 3.5 of 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 superluminescent diodes (SLDs) that provide high optical power, wide optical bandwidth, low spectral asymmetry, low gain ripple, high central degree of second order temporal coherence, fast centroid wavelength stabilization, and multi-decade environmental lifetime for use in strategic-grade high-precision inertial sensors such as interferometric fiber-optic gyroscopes (IFOGs) and accelerometers.

DESCRIPTION: The performance requirements for strategic and navigation-grade inertial sensors based on optical interferometry continue to become more stringent, necessitating continued innovation for optical component technologies. For example, IFOGs used in inertial navigation systems for fleet ballistic missile (FBM) submarine applications require unprecedented precision, characterized in terms of long-term bias stability, scale factor linearity, and angle random walk (ARW) performance.

A key component in these types of sensors is the light source. In principle, SLDs are an attractive option for such optical inertial sensors and are indeed employed in a number of commercial off-the-shelf (COTS) IFOGs. However, the relatively low optical power available from COTS SLDs limits the miniaturization of sense coils needed to achieve given ARW requirements, and furthermore is problematic with regard to splitting the optical power between multiple sense coils. In addition, inertial sensor performance may be limited by insufficient optical bandwidth, gain ripple, central degree of second order temporal coherence, centroid stabilization time, and environmental lifetime of COTS SLDs.

Therefore, the need remains for new technical approaches to improve SLD performance for interferometric inertial sensor applications. The objective of this topic relates to advanced SLDs designed for high-precision interferometric inertial sensors. In particular, SLDs are required with 1,550 nm operating wavelength, high optical power, wide optical bandwidth, low spectral asymmetry, low gain ripple, high central degree of second order temporal coherence, fast centroid wavelength stabilization, and at least thirty (30) year environmental lifetime.

PHASE I: Perform an analysis of design and materials aimed at an SLD that achieves stable performance over at least thirty (30) year lifetime for interferometric inertial sensor applications as compared to the current state of the art via novel designs, materials, and fabrication processes. Assess device performance parameters of fabricated test structures; consider all aspects of device fabrication; include a preliminary assessment of long-term environmental stability based on a materials physics analysis; and justify the feasibility/practicality of the approach. Propose, in a Phase II plan, a specific device design for fabrication based upon this analysis.

PHASE II: Fabricate and characterize a lot (up to ten (10)) of prototype SLDs in complete thermoelectrically cooled packages including lens-coupled fiber-optic polarization-maintaining pigtails, integrated isolators, and electrical connectorization suitable for incorporation into test beds for interferometric inertial sensors. Ensure that characterization testing is in accordance with MIL-STD-202, MIL-STD-750, and MIL-STD-883. Characterization testing comprises (1) optical power as a function of diode current; (2) polarization extinction ratio; (3) spectral characterization including sensitivity of centroid wavelength, optical bandwidth, gain ripple, and spectral asymmetry to diode current, chip-on-submount temperature, and case temperature; (4) and sensitivity of relative intensity noise (RIN) and central degree of second order temporal coherence to diode current, and centroid wavelength stabilization time. Perform an accelerated aging study involving SLDs under environmentally challenged conditions to develop a predictive model of long-term environmental stability. Perform a proof-of-concept study of one or more prototype SLDs in a suitable IFOG test bed. Deliver the prototypes by the end of Phase II.

PHASE III DUAL USE APPLICATIONS: Continue development that must lead to productization of SLDs suitable for interferometric inertial sensors. While this technology is aimed at military/strategic applications, SLDs are heavily used in many optical circuit applications including optical coherence tomography (OCT). An SLD that can meet the stringent performance requirements of strategic and navigation grade inertial sensors is likely to bring value to many existing commercial applications. Also, technology meeting the Navy needs could be leveraged to bring IFOG technology toward a price point that could make it more attractive to the commercial markets.

REFERENCES:

1. Adams, G. and Gokhale, M. "Fiber optic gyro based precision navigation for submarines." Proceedings of the AIAA Guidance, Navigation and Control Conference, Denver, CO, USA, vol. 1417, 2000. https://arc.aiaa.org/doi/pdf/10.2514/6.2000-4384

2. Ashley, Paul R., Temmen, Mark G. and Sanghadasa, Mohan. "Applications of SLDs in fiber optical gyroscopes." Test and Measurement Applications of Optoelectronic Devices, Vol. 4648. International Society for Optics and Photonics, 2002. https://www.spiedigitallibrary.org/conference-proceedings-of-spie/4648/1/Applications-of-SLDs-in-fiber-optical-gyroscopes/10.1117/12.462647.short

KEYWORDS: Superluminescent Diode; SLD; Inertial Sensor; Fiber-optic Gyroscope; Navigation; Optical Power; Light Source