DON26BZ01-NV012 TITLE: Optical Power Limiters Countering Frequency Agile Lasers and Dazzlers

COMPONENT TECHNOLOGY PRIORITY AREA(S): Advanced Materials;Directed Energy (DE);Space Technology

PROJECTED CMMC LEVEL REQUIREMENT: Level 2 (Self)

OBJECTIVE: Develop Mid-Wave Infrared/Long-Wave Infrared (MWIR/LWIR) nonlinear optical (NLO) dyes embedded in sol-gel glass operating as an Optical Power Limiter that protects optical sensors from damage caused by high-intensity light by reducing transmittance at high input power levels such as from frequency agile lasers and dazzlers.

DESCRIPTION: The proliferation of commercial, visible, and infrared wavelength laser systems is increasingly becoming a threat to our warfighters, which drives the need for further research and development for electro-optical/infrared (EO/IR) sensor. Current fielded sensor protection equipment is limited to fixed wavelength filters. However, broad band filters that are designed to circumvent multiwavelength laser threats are plagued by low transmittance, which degrades the sensitivity and performance of the sensor. Future warfighter threats include frequency agile lasers and dazzlers which have the potential of defeating fixed filters. Self-activating (passive) devices, where protection is activated by the incoming radiation (optical limiters), are the best approach to counter frequency agile and short pulse laser threats. The current state of the art of optical limiters are hampered by off-state low transmittance, low laser damage threshold, high activation laser threshold, and narrow field-of-view (FOV) and bandwidth. In addition, a sensor’s size, weight, and complexity greatly affect the user’s acceptance as a potential optical-limiting device. A sensor protection device is generally designed as an insert, an add-on, or replacement to the optical system. The optical limiter must be designed not to impact the sensor’s FOV and optical transmission. Currently available systems are very bulky and narrow band in their protection.

This SBIR topic solicits new, innovative NLO dyes embedded in sol-gel glass to provide sensor protection from frequency-agile laser and dazzlers operating in the MWIR/LWIR spectrum. The proposed NLO dyes embedded in sol-gel glass should allow ample transmission of ambient MWIR/LWIR light and be of high optical quality so as not to significantly degrade sensor performance. It should have a fast response time when exposed to dangerous fluence levels, sufficient to react to and block incident laser pulses to a high optical density. The dyes should be capable of changing from a high transmission state to a very low transmission state within sufficiently short time to block nearly all of the light contained in a light pulse emitted from frequency agile lasers and dazzlers . When harmful radiation is no longer incident, it must recover to a high transmission state in a short amount of time so that the sensor’s optics are not interrupted or significantly degraded after exposure. The proposal should discuss in detail the spectral transmittance in the attenuating state, activation threshold, response time, optical density in the attenuating state, and recovery time of the technology, the electric and other parameters of the excited state to be taken for measurements, excimer formation as well as any other important technical details.

The NLO dyes embedded in sol-gel glass critical requirements are:

1) Wavelengths – threshold MWIR 3 to 5 micron goal MWIR/LWIR 3 to 12 microns;

2) Response time: < 1ns

3) Recovery time: < 1ms

4) Low-intensity transparency is > 50%

5) For light intensity or fluence above the limiting threshold (LT), the attenuation is > 20dB

6) The Damage threshold (DT) is at least 10 times larger than that of the nonlinear optical material used

7) The fluence limiting threshold (LT) is below 500 milli-joules/cm^2/pulse

8) Multiple use without performance degradation exceeds 10,000 pulses

9) Wide acceptance and protection angles

10) Testing should be performed using f-number optics no greater than f/10, unless a higher f-number is required by a specific application

11) Dynamic range (~120 dB)

12) Rapid response time (~20 us)

13) Optical limiting threshold of 6.5 W / cm2 at room temperature.

Use of government materials, equipment, data, or facilities will not be offered and will not be required. If the technology is capable of exceeding any of the above requirements, the proposal should note this as well. Likewise, the proposal should note any limitations inherent to the proposed technology.

New and innovative material solutions may be proposed to provide new options for sol-gel glass production. Potential candidates include but are not limited to vanadium dioxide, use of commercially available or novel silanes and solvents. Processing approaches could include methods to control the rate of curing of the glass and the type, material, and shape of container used for the cure, as well as the cure temperature.

The goal is to develop a process that can make larger optical elements more reliably. Well established materials and processes may be proposed with a focus on improving the manufacturability, producibility, and reliability for current and next generation optical elements. Increasing size, manufacturing yield, and reducing cost while at the same time reducing manufacturing variability is desired. Proposers must have experience in the production of dye containing sol-gel glasses.

A second requirement of the optical elements are dyes which have the required optical transmittance/absorbance properties while being compatible with the sol-gel materials and production methods and are reliably available from domestic sources. This is currently a challenge. The performer will be required to identify suitable dyes for the optical elements and to design synthetic approaches to any dyes that are not commercially available from reliable domestic sources. The performer will synthesize any required dyes not commercially available from domestic sources in amounts exceeding 10 grams by the end of Phase II and have the capability to produce the dye(s) at batch sizes of at least 10 grams going forward or to work with another domestic producer to do so, or both. Proposers should have documented experience in the design, synthesis, and production of novel and existing absorbing and fluorescing dyes in the infrared regions of the spectrum and must have demonstrated the ability to reliably and reproducibly synthesize, purify, and characterize light-absorbing dyes at greater than 10-gram batch size. The proposal should clearly identify the current state of the art of the sol-gel and dyes of interest including both technical and manufacturing readiness and how the proposed work will advance readiness for the proposed optical elements.

Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by 32 U.S.C. § 2004.20 et seq., National Industrial Security Program Executive Agent and Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA) formerly Defense Security Service (DSS). The selected contractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances. This will allow contractor personnel to perform on advanced phases of this project as set forth by DCSA and NAVAIR in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material during the advanced phases of this contract IAW the National Industrial Security Program Operating Manual (NISPOM), which can be found at Title 32, Part 2004.20 of the Code of Federal Regulations.

PHASE I: Develop a NLO dye embedded in sol-gel glass protection concept designed to meet the (NLO) dyes embedded in sol-gel glass critical requirements stated. Identify critical fabrication processes for realizing this concept. Conduct theoretical analysis and limited laboratory laser irradiation experiments on sample materials or devices to prove the feasibility of the concept.

Demonstrate a clear ability to prepare at least 1 inch diameter optically clear sol gel glass boules that are suitable for cutting and polishing. Demonstrate experience in putting organic or organic/inorganic dyes into the sol gel and preparing 1 inch diameter optically clear sol gel boules that could be cut and polished into optical flats. Provide description and photos of procedures utilized in "Phase I-like" effort that will carry into the Phase II proposal. The Phase I deliverables will also include prototype plans to be developed in Phase II, 3-dimensional model, Weight Budget, Trade-off analysis, and preliminary lab test data and supporting analysis.

All NLO dyes embedded in sol-gel glass protection prototype testing is expected to be performed at the awardee’s site with the awardee’s equipment (no Government supplied equipment). Any remaining concept refinements needed after a Phase I completion will be addressed early in the Phase II effort, ideally in parallel with the design efforts.

PHASE II: Develop and demonstrate a NLO dye embedded in sol-gel glass protection prototype system. Prototype optical limiting for mid-infrared transparent windows should be built in the form, fit and function of, or integrated for use in conjunction with, common Embedded Image Periscopes (EIPs) or embedded vision blocks on ground combat vehicles. This a NLO dye embedded in sol-gel glass prototype shall be jamming, damage, and device tested for critical requirements listed in the Topic Description, broadband laser protection performance, linear absorption, and degradation to optical system performance in a laboratory environment. Factors to be considered for Advanced Naval Technology Exercise demonstration include, but are not limited to, optical density upon laser illumination, response time, recovery time, linear optical properties under normal daylight illumination, manufacturability, and environmental stability. Phase II deliverables will include a prototype a NLO dye embedded in sol-gel glass laser protection system limiter satisfying the critical requirements as specified in the Topic Description, interim sample materials (if applicable), test data, monthly progress reports, semi-annual progress reviews, a final review, and a final report.

The design process should include planning for demonstration and testing/measurements. Fabrication and demonstration of a prototype is expected to require a substantial portion of the Phase II program due to component purchase lead times and several iterations of fabrication to refine the process. With proper planning for demonstration and testing, the final portion of the Phase II program should be relatively short and produce high quality data that indicates the NLO dyes embedded in sol-gel glass protection prototype function as a high-quality optical component near a virtual focal plane.

It is probable that the work under this effort will be classified under Phase II (see the Description section for details).

PHASE III DUAL USE APPLICATIONS: Pursue commercialization of the various technologies developed in Phase II for transitioning expanded mission capability to a broad range of potential government and civilian users and alternate mission applications. Phase III award may be for additional research and development or direct procurement of products and services developed in coordination with the program.

Commercial applications could include coatings on car windows to attenuate incoming headlights, and coatings on windows of buildings to reduce heating from the sun. This system could be applied to other military platforms as well as the commercial and private airline industries as a defense against real world terrorist threats.

REFERENCES:

1. Vella, J. H. et al. "Experimental Realization of a Reflective Optical Limiter." Phys. Rev. Appl., vol. 5, no. 6, June 2016, p. 064010. doi: 10.1103/PhysRevApplied.5.064010
2. Alam, M. Z.; Schulz, S. A.; Upham, J.; De Leon, I. and Boyd, R. W. "Large optical nonlinearity of nanoantennas coupled to an epsilon-near-zero material." Nat. Photonics, vol. 12, no. 2, February 2018, pp. 79-83. doi: 10.1038/s41566-017-0089-9
3. Mann, S. A. et al. "Ultrafast optical switching and power limiting in intersubband polaritonic metasurfaces." Optica, vol. 8, no. 5, May 2021, p. 606. doi: 10.1364/OPTICA.415581
4. C. Wan, Z. Zhang, et al. "Ultrathin broadband reflective optical limiter" Laser Photonics Rev., 15 (6) (2021), Article 2100001, 10.1002/lpor.202100001
5. J. King, C. Wan, et al. "Electrically tunable VO2–metal metasurface for mid-infrared switching, limiting and nonlinear isolation", Nat. Photonics, 18 (1) (2023), pp. 74-80, 10.1038/s41566-023-01324-8

KEYWORDS: Sol-Gel Glasses; Laser protection; Frequency-agile laser; Dazzlers; Mid-Wave Infrared; Long-Wave Infrared

TPOC:
NAVAIR SBIR/STTR POC
navair-sbir@us.navy.mil