Atch A - FY11 JTO BAA Topics 20Jun2011.doc

BAA 11-RD-02

BROAD AGENCY ANNOUNCEMENT

HIGH ENERGY LASER - JOINT TECHNOLOGY OFFICE (HEL-JTO)

TECHNICAL TOPIC AREAS

Attachment A

Technical Topic Area 1: DIODE LASERS “Diode lasers have the highest electrical to optical efficiency of any laser system. Their energy can be converted to laser output with excellent beam quality and power scalability through the diode pumping of other types of lasers. Although different lasers require unique diode pump sources to efficiently couple into the gain media, the desired improvements have significant overlap. All diode pumped lasers will benefit from: (1) high efficiency and brightness over a range of temperatures, particularly as the temperature increases from 20-80°C; (2) efficient overlap of pump spectrum and absorption spectrum; and (3) a center wavelength and bandwidth that remain constant as a function of temperature and stress.

DL-1: Advanced Diode Design

Point of Contact: LTC John Hartke, (845)938-8611, e-mail: john.hartke@usma.edu Maximum award amount per task order NTE: $500K/1st year, NTE $1M/2nd year Technical period of performance may not exceed 12 months Proposals are sought to address innovative and advanced concepts in laser diode design (at any standard pump wavelength), architecture, and materials with the goal of dramatically improving any of the key performance parameters: efficiency, high temperature operation, increases in internal cavity damage threshold, wavelength stabilization, brightness, or cost, while maintaining performance capabilities of the other parameters. “

DL-2: Pump Sources for Alkali Lasers Point of Contact: Kevin Hewett, (505) 853-2684, e-mail: kevin.hewett@kirtland.af.mil Maximum award amount per task order NTE: $1M Technical period of performance may not exceed 12 months

Scaling efforts need appropriate pump sources. Innovative research proposals for pump sources with the following attributes are sought:

a. Match the optical pump transition for one of the alkali atoms. This means that the center wavelength must be at 767 nm for potassium, 780 nm for rubidium or 852 nm for cesium.

b. The center wavelength shall not drift more than 25% of output bandwidth over the entire operating temperature range.

c. The output beam leaving the device (after collimating optics / narrowing elements, etc) should have divergence less than 10 mrad in the fast axis and less than 20 mrad in the slow axis.

d. The pump source should have a center wavelength tunability of at least 70 GHz to maximum flexibility. (Ask for clarification as to what this is for)

e. The output bandwidth of the pump sources should be between 150 GHz (threshold) and 20 GHz (objective).

f. The output power of the packaged pump source should be between 500 W (threshold) to 1000 W (objective).

g. The pump sources developed should be manufacturable.

DL-3: High Performance/Affordable Diode Pumps Point of Contact: Gary Wood, 301-394-0932, e-mail gwood@arl.army.mil

Maximum award amount per task order NTE: $1M Technical period of performance may not exceed 12 months

This topic area seeks to lower the cost of diode packages for pump sources without sacrificing diode laser performance. Solid state lasers for high average power rely on diode pumps to greatly increase efficiency. While individual diode lasers have dropped in cost without sacrificing performance, diode array costs have remained steady. Fiber coupled multi-emitter modules have a cost per W that is about 10X the single emitter cost. Since most of cost of a diode pumped solid state laser is the cost of the diode packages, these lasers could be more affordable with lower cost diode arrays. Affordability is a major driver to eventual transition of any high average power laser based directed energy weapon into a service program of record. The additional cost of fiber coupled diode arrays is in the packaging and optics to efficiently couple the diode power into the fiber. For this technical topic the diodes of interest are pump sources for fiber lasers and amplifiers. The specific pumps of interest are for Yb pumping (976 nm) into a 200 micron diameter fiber with a 0.22 NA. Diode manufacturing processes are sought that can reduce the necessary materials, process steps and minimize human involvement. This will ensure high quality diode production and ensure reproducibility, leading to higher yields and lower costs. The goal is a 10X reduction in current fiber coupled diode laser packages without a loss in SOA performance. Utilizing chip and/or modular design approaches as well as some automation would allow for standardization at the component level which can reduce production costs. Performance as measured in output power; efficiency; beam quality (brightness); and weight to output power ratio should remain at SOA or improve. It is envisioned that technologies and techniques that could address these improvements would be advances in thermal management materials, structures and devices; reduced electrical resistance; innovative designs and improvements in diode beam quality. For bars and stacks smile is a critical parameter and needs to be reduced (ideally to < 0.5 microns). In summary, fiber pump sources are sought that can be manufactured in quantity that will reduce the cost of an array package by ideally 10x from currently available packages and maintain or improve SOA brightness, size and weight.

Technical Topic Area 2: FREE ELECTRON LASERS (FEL)

Point of Contact: Quentin Saulter, (703) 696-2594, e-mail: quentin.saulter@navy.mil Maximum award amount per task order NTE: $1M

Technical period of performance may not exceed 12 months

Further power scaling in the FEL requires significant technology developments in several areas. This Technical topic concentrates on FEL injector technology and the fundamental physics and engineering issues related to scaling the output power of the FEL up to and beyond the nominal megawatt range. HEL-JTO understands that many industries and laboratories would not be able to conduct most of the experiments at the beam parameters required for these efforts, but collaborative research with national laboratories may be needed to complete the proposed efforts.

FEL-01: FEL Injectors

A critical component of high power free electron lasers is the injector where the electric fields inside the injector cavity must be large enough to overcome the space charge, resulting in a low emittance, high current beam. The emerging consensus is that Superconducting RF injectors are the most likely way to create the high brightness, low emittance beam necessary for the FEL to reach MW class levels. Superconducting RF guns offer the potential for higher gradient and voltage in continuous wave operation due to decreased losses. Proposals are sought for research in the design, modeling, development and fabrication of SRF photocathode and thermionic injectors, as well as in MW RF input couplers and booster cryomodules for the SRF injector.

FEL-02: FEL Megawatt Electron Beam Physics and Engineering FEL Megawatt Electron Beam Physics and Engineering: Performance of basic and applied research on the physics and technology relevant to FEL and MW class future systems. Proposals are sought for studies that include MW electron beam and optical beam physics, modeling and simulation for FEL cathodes, injectors, accelerators, and architectures. Design and development of FEL components based on these studies should follow.

Technical Topic Area 3: ADVANCED CONCEPTS Point of Contact: LTC John Hartke, (845)938-8611, e-mail: john.hartke@usma.edu Maximum award amount per task order NTE: $500K/1st year, NTE $1M/2nd year Technical period of performance may not exceed 12 months Proposals for the Advanced Concepts topics are intended to be higher risk, higher potential payoff, and longer range to pay-off than the other topics of this technical topic. The proposals should address key technical barriers of HEL development that are proving difficult to resolve with more established approaches. The proposal should present a clear and compelling understanding of the specific challenging HEL technology barrier(s) being addressed, and the limitations of conventional HEL approaches that this unorthodox approach will attempt to alleviate. Failure to address these important aspects of the proposal will result in a proposal being found to be non-responsive. A proposal may also be justified in terms of the need to avoid the potential of technological surprise in the development of specific leap-ahead performance enhancements in HEL technology and systems.

AC-1: Develop Optical Elements and Increase Survivability in a HEL system

Proposals are sought for durable, low absorption, low-scatter optics and coatings, and for innovative and advanced concepts in materials and designs with the goal of increasing the survivability of optical elements and coatings within the optical train of an HEL system. This includes, but is not limited to, particulate contamination resistance, humidity resistance, and coating adhesion to optical elements. Ruggedized, durable coatings are desired which can withstand total powers of 150kW with irradiance levels as high as 100kW/cm2. Additionally, coatings and substrates should transmit from the visible to the mid-wave infrared (up to 5 microns). Key figures of merit for the substrates are low absorption at laser wavelengths, high transmission in the visible to mid-wave spectral region, and high thermal conductivity. The offeror should show that the product will be cost competitive with current substrates, such as fused silica, and have superior performance to fused silica in one or more of the figures of merit, while maintaining performance capabilities of other parameters.

AC-2: Beam Combination

Proposals for this topic should address advanced concepts in beam combination, with the goal of substantial improvement over existing approaches in combining beams from several sources to efficiently maximize power in the bucket.

AC-3: Laser Damage Assessment Technologies

This topic requests research in methods and technologies in systems that provide detection of damage or reduced operability to critical components on a platform that is being engaged by a high power laser. Of particular interest are passive methods, but innovative active methods will also be considered. Components of particular interest are those that reduce a platforms capability while not reducing its maneuverability such as sensors, cameras, and communication links.

AC-4: Laser Sources for Detection

This topic request research in lasers and associated systems that provide a capability for proactive threat detection. That is, systems that use a laser to scan a region to detect aircraft for subsequent hand over to an acquisition system. Systems that are integratable with and share resources with an acquisition, tracking and aimpoint designation system are of particular interest. Laser wavelengths proposed must be eyesafer and propagate well through the atmosphere (e.g. 2 micron region).To be considered responsive, white papers in this area must address systems that can be matured into military useful packages (small, light weight, rugged and reliable). Discussion of laser sources proposed for research should include a discussion of the sensor that would be used with that source and the maturity and availability of that sensor.

Technical Topic Area 4: SOLID STATE LASERS.

Point of Contact: Gary Wood, 301-394-0932, e-mail gwood@arl.army.mil

Maximum award amount per task order NTE: $1M Technical period of performance may not exceed 12 months

Proposals for this area should address enabling technologies for high average power (>100kW) solid state lasers, SSL, with excellent beam quality (<1.5 x DL), short turn on times (<1 s), long run times (>minutes) fieldable on military platforms for various applications. Research and development in these areas should show scalability to high average power. All SSL research and development should make high efficiency, high beam quality and scalability to high average power a prime consideration. Proposals of particular interest for the solid state laser area should address research and development in the following two areas (not in a priority order):

SSL-01: Specialty Fiber Design

a. Gain fibers

All scalable fiber lasers or amplifiers need to address SBS, and other nonlinear effects, as well as mode control. Conventional glass fibers, in large part originally designed for the telecommunications industry, are easily available with excellent properties such as low loss, ability to splice, flexible format and mode control via micron sized cores. In addition, these fibers are easily available and perform as specified. However, these more traditional laser fibers are not amenable for scaling to high average power. Large core fibers offer some scalability and a significant reduction in SBS and other nonlinear effects, but the large cores beyond certain sizes have issues with mode control. Non-conventional fibers, (i.e. materials other than glass, fibers with structure beyond the step-index, etc.), may offer solutions to mitigate both SBS and other nonlinear effects as well as better mode control, but often have issues with loss, flexibility and lacking spliceability. In addition, these fibers are not always mass producible and can lack reproducibility. Improvements are sought in specialty fibers such that they can be made: scalable to high powers; spliceable; reproducibly manufacturable; sufficiently flexible. They also have to offer much better thermal management, have reduced SBS and other nonlinear effect thresholds and have superior mode control.

b. Non-gain fibers

Delivery fibers are sought for high power fiber delivery of laser radiation to allow high power laser sources to be decoupled from the eventual launch position. Specialty fibers are sought for beam clean up and improvements in beam quality. Specialty fibers are also sought for integrated optical elements such as Faraday rotators.

SSL-02: Ceramic Gain Material

This topic requests research into processes and technologies that provide enhancement to the manufacturability of current and innovative design of ceramic gain material.

Technical Topic Area 5: BEAM CONTROL

Point of Contact: Dan Herrick, 505-853-5189, dan.herrick@kirtland.af.mil Maximum award amount per task order NTE: $1M

Technical period of performance may not exceed 12 months BC-01: Wavefront Control Components

Proposals are sought for Beam Control Components, as described below, for testing in DEW (Directed Energy Weapons) Demonstration platforms with a total power of up to 150 KW from a Solid State Laser (SSL) or a fiber-laser system with a 1.06 +/- .02 µm wavelength. All components may be tested in the laboratory with final testing to be accomplished in a relevant environment. The offeror must show scalability to the goals or alternative methods for achieving equivalent performance. Developed components should be deliverable standalone components with complete documentation and control software, where applicable, and be suitable for further government testing. The wavefront control system is meant to address a Katyusha-class target with a depressed trajectory at range 9 km in a HV 5/7 atmosphere. The output aperture of the system will be 30-50 cm.

a) Advanced Wavefront Sensor (WFS)

Current design studies indicate the need for a wavefront sensor to operate close to the HEL wavelength, typically in the 1 to 1.1 µm region. The WFS must be able to accurately sense and reconstruct wavefronts from a beacon that has propagated through a turbulent atmosphere characterized by an r0 as small as 0.03 m and a Rytov number up to 1.0. The sensor frame rate along with data transfer and processing latencies should be able to support up to 50 kHz sample rates and a ~2.5 kHz closed loop bandwidth. The sensor should have high quantum efficiency and low noise. The sensor should be time gateable to permit range gating for background rejection and should support a 100 nanosecond or less integration time per sample. The table below lists the expected parameter space for the WFS. The “Threshold” column indicates the minimum acceptable performance and the “Objective” column indicates the desired performance. The offeror should show how the proposal will demonstrate key performance parameters that would substantially reduce the risk of achieving the desired performance.

These specifications are provided as a guide and may not apply to all concepts (beaconless concepts, for example) and they may be too aggressive. The offeror should show that the proposed concept meets the requirements listed or show how the proposed concept will operate in the severe environment described above.

b) Illuminator Lasers

AO beacon illuminators are necessary for Tactical DEW range extension. SWaP considerations will be important for fielded systems and should be part of initial studies. Performance parameters for such laser are:

BC-02: Beam Alignment and Stabilization on Dynamic Platforms (IRU)

Less costly inertial reference units (IRUs) to meet requirements for targeting and firing laser weapons from a variety of platforms while on the move are needed. These dynamic scenarios are challenging from the standpoint of absolute knowledge of platform position and orientation (for predictive avoidance and target acquisition and de-confliction), as well as line of sight stabilization in the high vibration environment in which the HEL must operate.

Ideally, one IRU could fulfill both roles, having low drift, for precise attitude determination, and good high frequency characteristics, along with a guide beam to mitigate optical train jitter. If not quantified, the resulting LOS jitter can increase noise in target state estimates, leading to more jitter and decreased track continuity.

IRUs capable of quantifying optical train jitter to <1 urad, 3 sigma while, providing attitude information with very low drift (<1 mrad / day and a desired goal of 1 µrad / hr.) are of interest. This performance should be attainable while operating in typical vibration environments of tactical HEL platforms. Proposed approaches should give adequate consideration to reliability, maintainability and size, weight, power (SWAP) and unit cost. The technical approach should be consistent with a LRIP cost of less than $500k per unit.

BC-03: Tracking

Proposals are sought for technologies that facilitate the rapid development and integration of tracking and image processing functions into HEL weapons. Proposed approaches should facilitate functions such as rapid model based development (e.g. using Simulink, Matlab, etc.) and hardware in the loop (HIL) testing at video rates of 60 Hz and above. A secondary goal for proposed approaches is the mitigation of intellectual property issues via the use of widely adopted standard technologies, middleware, development tools and interfaces. Efforts should also leverage existing HEL interface specifications and standards whenever possible. Examples of the latter include joint government efforts currently underway within the beam control TAWG. A long-term goal of this effort is the definition and construction of a hardware/software platform that could host a wide variety of different tracking algorithms, with a library of appropriate image processing functions, and development tools to facilitate rapid prototyping.

BC-04: Phased Arrays Proposals are sought to further component technology for optical phased array weapon systems. Special consideration will be given to proposals that include integration with the functions of tracking, aimpoint maintenance, beam pointing and beam formation necessary for a full weapons system. Technology should be scalable to a target projected aperture of 50 cm having a + 45° field of regard.