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GHz burst mode ultrashort pulse laser

Description:

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Directed Energy (DE)

 

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: The Air Force seeks the development of robust, compact, extreme repetition rate, high per pulse energy ultrashort pulse lasers with pulse on demand capability. Specifically, we seek advancements towards developing a turn-key GHz or higher repetition rate in a burst mode system. Ideally this system has a tunable rep-rate. It is desirable to have two operational modes: one that is externally trigger-able to sub-millisecond timing that yields a series of a few bursts and another that allows the system to continuously fire bursts at 1 Hz or better for up to several seconds. The resulting system at minimum should be compact or clearly scalable to compact package and be maintainable by non-specialists or minimal maintenance from laser experts.

 

DESCRIPTION: The Air Force Research Laboratory seeks to find novel ways to counter rf and EO/IR sensors and effectively ablate materials. The Air Force is seeking innovations towards developing burst mode lasers with tunable pulse trains of 1-20 GHz rep rate with individual pulses on the order of 100 mJ, pulse durations on the order of 1 ps, and bursts of 10 pulses or better. The Air Force seeks development of a system that operates in two modes: externally triggerable 'on-demand' burst mode with sub-millisecond trigger delay, and a continuous mode that allows for burst to occur at 1 Hz or better for several seconds. This system would allow the Air Force to further explore the feasibility of adopting such technology for military utility. A successful project will document, design, and test a laser system that meets these specifications. Such a solution may include commercial-off-the-shelf components, however will require novel laser engineering to achieve the desired burst pulse characteristics. A successful system should be compact and require minimal maintenance. Basic day to day operation should be achievable by a non-expert, e.g. turn on and shut down of system does not require a laser engineer to realign system frequently, changing frequencies should not require manual moving of optical components. If proposers find that the requirements in all parameters are infeasible, they should propose to what they believe can be achieved and evaluations will be scored accordingly. Intra-burst rep rate tunability and pulse-on-demand are the highest air force priorities for this effort, although the high frequency rep rate target values should be as-achievable. Pulse duration, number of pulses per burst, inter-pulse rep rate, and energy requirements are more flexible, but should be sufficient to demonstrate desired nonlinear laser-plasma interactions for air force applications. In addition to demonstration of laser technology goals, calibrated measurement of tunable rf resulting from the laser plasma, burn through rates on selected samples, and characterized supercontinuum in selected samples will be considered major milestones for the final product.

 

PHASE I: Phase I will consist of designing, costing, and specifying components needed for the planned system. Periodic updates will be required to ensure team is on track to meeting project objectives. System design should be supported by modeling and engineering calculations to support the design feasibility. Model should provide clear performance goals for the final laser specifications (ie pulse profiles, wavelength, energy, trigger modes) that the system should aim to meet in Phase II. Applicants should provide proof of concept/breadboard demonstration for novel and/or high risk concepts key to phase II success. Applicants should detail a statement of work with timelines of system development and personnel required for its successful completion.

 

PHASE II: Phase II should continue to build off the foundation laid in Phase I. Awardee(s) should execute design proposed in Phase I and benchmark system's capabilities. During this time applicants should continue to iterate and improve on design to better meet the goal of tunable GHz burst mode laser with ~100 mJ, and ~ps individual pulses. The end of Phase II should result in a prototype that meets the goals of this project that is compact, or with clear paths to being compact, and operable by non-experts. An ideal final system will not require manual movement of optical components by personnel to change the laser operation. In addition to demonstration of a laser system that meets goals of the project, calibrated measurement of tunable rf resulting from the laser plasma, burn through rates on selected samples, and characterized supercontinuum in selected samples will be considered major milestones.

 

PHASE III DUAL USE APPLICATIONS: If laser-material interaction milestones of phase II are sufficiently promising, the air force will seek phase III funds to further develop and acquire a laser system that is compact, ruggedized, and commercially available and which meets thresholds requested by the topic. We anticipate TRL 3 at entry of Phase III. Depending on magnitude of RF demonstration milestone in phase II, DAF demonstration follow-on funding may be sought to support phase III development and transition to TRL 6.

 

REFERENCES:

  1. G. Blair, P. Sprangle. "Generation of rf radiation by low-intensity laser pulse trains in air," in Phys. Rev. E, vol. 108, pp. 015203, 2023.;
  2. Danielle Reyes, Haley Kerrigan, Jessica Peña, Nathan Bodnar, Robert Bernath, Martin Richardson, and Shermineh Rostami Fairchild, "Temporal stitching in burst-mode filamentation," J. Opt. Soc. Am. B 36, G52-G56 (2019);

 

KEYWORDS: burst mode laser; ultrashort pulse; high repetition rate; pulsed laser; high average power

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