N151-018 TITLE: Integrated Laser and Modulator

TECHNOLOGY AREAS: Air Platform, Sensors, Electronics

ACQUISITION PROGRAM: JSF-MS

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 5.4.c.(8) of the solicitation. 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 an integrated laser and intensity modulator for analog/radio frequency photonic links operating at 1.55 micron.

DESCRIPTION: Military communication systems on avionic platforms have very small size and low weight requirements. Fiber optic based links provide inherent advantages over electronic based systems due to ultra-wide bandwidth, immunity to electromagnetic interference and reduced weight. Despite the advantages provided by fiber optics, the size of an entire system is still limited by engineering tradeoffs such as the spacing required between components due to the fiber optic interfaces and the packaging size of individual components. Specifically, the required use of optical fiber between the laser and modulator limits the ability to create a compact transmit system. A standard system includes a laser, modulator and a photodiode receiver. Typically there is some active and/or passive signal processing that can be done post modulator, indicating that the laser and modulator are consecutive. Thus a small packaged integrated laser and modulator device is needed.

Recently low relative intensity noise (RIN) lasers and small form factor modulators have become commercially available. However, the challenges posed by integrating both components together in a very small form factor package without the aid of fiber has yet to be accomplished, as typically the laser and modulator are of differing materials. Some work has been done to integrate optical components monolithically [1, 2], and heterogeneously [3], but researchers have yet to demonstrate an integrated laser and modulator design at power levels needed for most radio frequency (RF)/analog photonic links.

RF/analog photonic links suffer from complexity and size since the components cannot be built on one chip. Avionic platforms, as well as radar applications, would benefit from a very compact integrated link. Integrated laser and intensity modulators operating at 1.55 micron are desired with a minimum linewidth requirement of less than (<) 200 kHz and ideally < 100 kHz, and relative intensity noise of < -169 dBc/Hz from DC to at least 20 GHz. The intensity modulator should have a 3 dB bandwidth of at least 20 GHz and ideally 40 GHz, with a radio frequency (RF) Vp < 3 V at 1 GHz, a reflection coefficient (S11) of < 15 dB and 25 mW output power when biased at quadrature. The extinction ratio is required to be > 20 dB but is desired to be > 25 dB. Typically, a laser and modulator interfaced via optical fiber are of different material types. The desired laser and modulator interface may be of the same or differing materials so long as the two are combined without the aid of optical fiber on a single chip, monolithically or heterogeneously. The integrated device should be designed such that dimensions in height and width are feasible for packaging at 1 cm by 1 cm with a length not to exceed 15 cm. Ideally, the dimensions should not exceed a packaging requirement of 5 mm by 5 mm by 10 cm for the integrated laser and modulator interface. The inputs should include a female K connector (2.92 mm) and bias control for the modulator, as well as laser bias and thermal electric cooler (TEC) control if necessary and a fiber output style ferrule connector (FC)/angled physical contact (APC) (FC/APC). Collaboration with an original equipment manufacturer (OEM) in all phases is encouraged, but not required, to assist in defining aircraft integration and commercialization requirements. TRL (Technology Readiness Level)/MRL (Manufacturing Readiness Level) assessments at the conclusion of each phase should be performed.

PHASE I: Design and analyze a new approach for an integrated laser and modulator device addressing the goals in the description. The approach to optical coupling or monolithic integration should be demonstrated in a bench top experiment as well as the electronic circuitry needed for RF and direct current (DC) bias and any temperature control if required. Perform modeling and simulation of the device and analyze required power handling and frequency requirements. Perform a proof-of-concept demonstration and a Technology Readiness Level (TRL)/Manufacturing Readiness Level (MRL) assessment.

PHASE II: Build, test and demonstrate a prototype heterogeneously integrated laser and modulator interface device with bench-top experiment showing 20 GHz bandwidth with 25 mW output power at quadrature and RF Vp of no more than 3 V at 1 GHz. Develop packaging suitable for transition to Navy aircraft applications and develop integration plan. Test prototype integrated laser and modulator in an RF photonic link with the objective performance levels reached. Characterize the packaged device over the full –40 to +100 degrees Celsius ambient temperature range. If necessary, perform root cause analysis and remediate packaged integrated laser and module failures. Deliver packaged laser prototypes on evaluation boards. Update TRL/MRL assessment.

PHASE III: Finalize packaging for transition to military and commercial applications. Develop plan and demonstrate capability to fabricate and package devices for military platforms and outline design for typical avionic ruggedness requirements. Perform final avionics integration activities and qualification testing. Demonstrate plan for device manufacturing.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The technology would find application in commercial systems such as fiber optic networks and telecommunications.

REFERENCES:
1. Hou, L., Wang, W., Zhu, H., Zhou, F., Wang, L., & Bian, J. (2005). Monolithically integrated laser diode and electroabsorption modulator with dual-waveguide spot-size converter input and output. Semiconductor Science and Technology, 20, 779-782.

2. Sysak, M. N., Raring, J.W., Barton, J.S, Dummer, M., Blumenthal, D.J., & Coldren, L.A.. (2006). A Single regrowth integration platform for photonic circuits incorporating tunable SGDBR lasers and quantum-well EAMs. IEEE Photonics Technology Letters, 18, 15, 1630-1632.

3. Ahmed, T., Butler, T., Khan, A. A., Kulick, J. M., Bernstein, G.H., Hoffman, A.J., & Howard, S. S. (2013). FDTD modeling of chip-to-chip waveguide coupling via optical quilt packaging. Proc. Of SPIE, 8844.

4. Department of Defense. (2011). Technology Readiness Assessment (TRA) Guidance. <http://www.acq.osd.mil/ddre/publications/docs/TRA2011.pdf

5. Department of Defense. (2009). Manufacturing Readiness Assessment (MRA) Deskbook. http://www.dodmrl.com/MRA_Deskbook_v7.1.pdf

KEYWORDS: Laser; Modulator; RF Photonics; Heterogeneous; Integrated; Packaging

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