Technical Questions and Answers for FA8650-20-S-1137.pdf

Technical Questions and Answers for FA8650-20-S-1137

Question 1

In Appendix 5 Statement of Objectives (SOO), Section 3.0 Objective/Scope, Paragraph 3, would the Government clarify the performance metric of “FULL POWER OF 280W (minimum)”. If the objective is delivery of 280 J of energy in one second or less, would the Government consider this energy delivery across times from 1 ns to 1 ms to provide clarity?

Answer 1

The objective is to deliver 280W of power. While this does equate to 280 Joules of energy per second, this does not translate to single pulse energies of this magnitude under the current specifications. The BAA technical requirement is CW or pseudo-CW (high repetition rates of greater than 1 MHz), and so energy delivery with a time period of 1 ns to 1 ms does not fall within the scope of this BAA. Similarly, a “burst” emission with CW or high repetition rate content would meet with the system requirements only during the “on” time and would fail to meet requirements during any dwell time. True CW or continuous >1MHz operation is what is being sought by this BAA.

Question 2

Appendix 5 SOO, Section 3.1 Tasks, Task 2, states a performance metric of “a power stability of 1% or better during a 30 minute operation period, and better than 5% absolute over any operating duration.” When comparing baseline and potential alternate approaches, this measurement may not provide a figure of merit. Would the Government replace this performance metric of “a power stability of 1% or better during a 30 minute operation period, and better than 5% absolute over any operating duration” with an acceptable performance measure of 5% pulse to pulse energy stability over the magazine depth? This metric is a consistent measure of current mission capabilities for this technology.

Answer 2

A 5% pulse to pulse energy stability over the magazine depth would be acceptable providing the average power stability requirement of 1% or better during a 30 minute operation period, and better than 5% absolute over any operating duration is also met.

Question 3

In Appendix 5 Statement of Objectives, Section 3.0 Objective/Scope, the Government will likely need to compare alternate approaches and laser concepts. Local spectral brightness offers a metric directly attributable to mission capabilities. Would the Government add local spectral brightness as a performance evaluation metric?

Answer 3

Local spectral brightness will be used as a performance evaluation metric, but only within the stated spectral brightness requirements of 200 mW of average power per nm of spectrum over a 50 nm integration window, true broadband, or in discrete lines spectrally spaced at no more than 50 nm (+/- 10%). This equates to a minimum average power of 10 W per 50 nm. Very spectrally bright features, such as singe longitudinal mode operation at any given wavelength, do not offer any evaluation advantage under this BAA.

Question 4

Does the laser output needs to be single-aperture or can be multiple apertures? Generally, it's hard to make a waveguide capable of guiding broadband light (350-1750) while maintaining high beam quality M2 < 1.5 because it is multimode for the light at short-wavelength.

Answer 4

The laser output need to be a single aperture.

Question 5

Does the laser output need to be optical fiber coupled or free-space collimated?

Answer 5

The laser output needs to be free-space collimated to within the specified beam quality.

Question 6

Based on the description of the opportunity, there are only requirements on beam quality, spectral power density and spectral range. Any other specific requirements on SWaP?

Answer 6

SWaP is not specified, but it is obviously always of interest to the Air Force.

Question 7

The BAA states that the laser line spacing can be up to 50 nm, but this corresponds to a dramatically different frequency separation at 350nm vs 1750 nm. Is it correct to assume that this is the maximum spacing on the long wavelength edge of the overall spectrum (i.e.

around 1750 nm)?

Answer 7

The specification for line spacing is in terms of nm throughout the required emission spectrum. Certainly this will correspond to very different frequency separations between adjacent lines across the spectrum of interest, but we require a frequency spectral density in terms of nm. For example, if you wish to design around discrete wavelengths, the maximum spacing should correspond to wavelengths 350 nm, 400 nm, 450 nm,……………, 1650 nm, 1700 nm, 1750 nm.