HR001124S0038_HAPPI_FAQ_Update_11_1_24.pdf

HR001124S0038

Heterogenous Adap vely Produced Photonic Interfaces (HAPPI)

Frequently Asked Ques ons (FAQ) Document Updated on November 1, 2024

Q1. What is the an cipated total funding for the HAPPI Program?

A1. Total funding for the program is $30M for 36 months. DARPA an cipates mul ple awards.

Q2. Does the 3um x 3um interconnect pitch scale with the center wavelength across the 400-1800 nm wavelength range, or is it constant for any center wavelength chosen within the range?

A2. It remains constant at 3um x 3um.

Q3. Does the spectral bandwidth of 100 nm scale with the center wavelength across the 400-1800 nm wavelength range, or is it constant for any center wavelength chosen within the range?

A3. It remains constant at 100 nm. The intent is to support broadband applica ons and avoid highly selec ve wavelength solu on. Geometric scaling is allowed, if necessary, as long as the approach does not have inherit bandwidth limita ons.

Q4. The BAA states that no specific material pla orm will be defined but it also men ons 100–500 µm thick semiconductor substrates. Are non-semiconductor substrates such as glass allowed?

A4. Glass and other non-semiconductor op cal materials are of interest and traversing interfaces between heterogeneous materials is highly encouraged. At least one of the materials in the heterogeneous stack may be a semiconductor as the pla orm must be able to support ac ve optoelectronic devices.

Q5. Will Abstract feedback be shared with the proposer team?

A5. Yes.

Q6. When will Abstract feedback be shared?

A6. A specific date for abstract responses cannot be provided. The processing time will depend on the number of submissions received.

Q7. Should UARCs contact DARPA before submission?

A7. Yes, UARCs will generally follow the instructions provided for FFRDCs. Please reach out through the BAA email if further clarification is needed.

Q8. Only one proposal is allowed per lead organization. Can we submit multiple abstracts?

A8. Yes.

Q9. Can technology or materials be used that are compatible with a foundry process, but not currently used?

A9. Yes.

Q10. Can modifications be done to the interposer and/or substrate at the BEOL?

A10. Yes.

Q11. What is the quantitative requirement on alignment?

A11. There is no alignment requirement in the BAA. Proposals should discuss alignment in the context of the proposed fabrication and assembly approach and the goal of achieving the loss metric. The approach to alignment should be compatible with automation and chip-scale manufacturing.

Q12. Can each layer have their laser, modulator or photodetectors?

A12. Integration of lasers, modulators or photodetectors is not required in the program.

They are allowed to be used in debugging, testing or calibration.

Q13. Should coupling be bidirectional?

A13. Yes.

Q14. Does the proposed material have to be CMOS-compatible?

A14. No. The proposals should discuss the pathway to manufacturability with the proposed materials.

Q15. Can you provide a funding range per proposal?

A15. DARPA does not specify funding range per proposal. We anticipate funding multiple proposals within the total program budget.

Q16. Is there an aggregate bitrate requirement or metric?

A16. Bitrate is not specified in the BAA. Data-transmission metrics are outside of the scope.

Q17. Do you have a target architecture or topology in mind?

A17. No. The architecture and topology are proposer defined.

Q18. Do you have a latency target for end-to-end path?

A18. There is no conversion or processing in the electronic domain. Therefore, we expect the latency to be time-of-flight.

Q19. How important is “reconfigurability” for HAPPI? Must the system architecture be “adaptable” or “tunable”?

A19. Reconfigurability and/or tunability is not required. “Adaptable interfaces” refers to any methods that may be used to achieve optical alignment post fabrication or assembly.

A20. Will the US Government be doing test and evaluation for the go/no-go milestones.

Q20. No. The data for the go/no-go milestones is supplied by the performers. Submission and approval of the test plans as well as live hardware demonstrations at the performer’s site are required per the BAA.

Q21. Is free-space optics ruled out?

A21. Yes. “Free space” is defined as unguided propagation in air. Refer to Q32 addressing small gaps occurring in chip-to-chip packaging. In such cases, microscale optical elements can be used as long as the solution is compliant with the specified array pitch.

Q22. Is there a minimum or a maximum number of waveguide layers for the originating or terminating PICs.

A22. The minimum number for both discrete chips is 4. The partitioning between the two chips can be 2-2 or 1-3. There is no maximum.

Q23. What does the minimum number of layers mean if the routing is not done by a layered approach?

A23. The HAPPI BAA (pg. 6) calls for transitions from in-plane to out-of-plane waveguiding and connections between multiple waveguiding layers per chip in a multichip stack. The approach should support traditionally produced waveguides. As stated in the BAA (pg.5), the “approaches should include coupling to a PIC platform with demonstrated optoelectronic components (sources, amplifiers, modulators, multiplexers, tuners, filters, detectors, and other optoelectronic components) while meeting the program loss and density metrics”.

Q24. What does 6.2 funding mean?

A24. It is DoD funding for Applied Research.

Q25. Are the current metrics subject to change?

A25. No.

Q26. Can the 3D routing footprint cover a larger area than the 2D coupling array?

A26. Yes. The proposer must show through analysis that the approach remains scalable and meets the BAA metric for the density and size of the coupling array.

Q27. Does the 3 µm pitch apply in vertical direction, between waveguide layers?

A27. No. The vertical pitch is performer defined.

Q28. Does the link array need to be square (3 mm x 3 mm)? Can it be rectangular with the same area?

A28. Yes, the array footprint is square, as specified in the BAA.

Q30. Is there a maximum height for the 3D routing?

A30. No, solutions should be compatible with chip scale integration and packaging dimensions.

Q31. Are there any polarization maintenance or polarization control requirements?

A31. No. Polarization maintaining or polarization invariant waveguides are not specified. Per the BAA, any approach should account for polarization-dependent losses and outline corresponding mitigation strategy.

Q32. The interface between the two chips is shown with zero gap. Is this meant to imply hybrid bonding (i.e. no solder balls)?

A32. All BAA graphics are for illustration purposes only. Both gapless and small gap (e.g.

accounting for solder ball thickness) are of interest. If a gap is envisioned, the optical path should be protected through standard packaging processes such as solder reflow, underfill, encapsulation, passivation, etc.

Q33. Is it envisioned to have electrical connections (in addition to optical connections) traverse the chip-to-chip interface?

A33. Yes. While it is not required for approaches to support coexisting electrical and optical connections through the chip-to-chip interface, it is highly encouraged.

Q34. Is there a power consumption requirement?

A34. No. Energy for one-time post fabrication trimming is unconstrained. However, any non-zero static power consumption may limit the scalability of the solution and should be addressed in the proposal.

Q35. Is international collaboration allowed?

A35. Yes. Per the BAA, “All responsible sources capable of satisfying the Government's needs, including both U.S. and non-U.S. sources, may submit a proposal that shall be considered by DARPA”.

Q36. Is there a requirement to implement “one to many” routing?

A36. No. All metrics in the BAA refer to point-to-point links.

Q37. What is the motivation for the requirement to traverse >100 µm substrate material?

A37. To enable optical through-substrate via, allowing vertical stacking of more than 2 photonic chips.

Q38. Is the HAPPI concept limited to 2-chip stacks?

A38. No. DARPA is interested in solutions, generalizable to more than 2 stacked dies.

Q39. Can the Phase 2 approach be demonstrated through die to wafer packaging?

A39. Yes.

Q40. How will ITAR issues be handled if foreign entities or individuals are performing on the program?

A40. Performers are responsible for determining and protecting ITAR information during program meetings and collaboration events.

Q41. Is there a preference for certain contract instruments?

A41. No.

Q42. If a performer is allowed to submit mul ple abstracts, but is allowed only one proposal, who should determine which approach is to be caried forward in the proposal?

A42. CORRECTED: The BAA does not restrict the number of proposals per organiza on. Mul ple proposals per organiza on are allowed.

Q43. Are broadband comb sources and/or modulators in the program scope?

A43. No.

Q44. The BAA references wavelengths in the 400 – 1800 nm band. Does the proposal need to cover the en re band?

A44. No. Covering 100 nm sub-band within the 400 – 1800 nm is sufficient.

Q45. Does the Government have a preference for a photonic foundry for technology transi on?

A45. No. DARPA will consider any foundry capable of reproducing and sustaining the technology for DoD use. For further guidance, reference the BAA, Sec on II: Evalua on Criteria, Poten al Contribu on and Relevance to the DARPA Mission.

Q46. Does the link array size refer to number of physical channels or data channels that may be mul plexed on fewer physical links?

A46. It refers to physical channels.

Q47. Should ac ve material pla orm be integrated in the final demonstrators in Phases 1 and 2, or should be just described?

A47. The ac ve material pla orm should be integrated and demonstrated in func onal links. The program metrics refer to measured performance on such links.

Q48. The 1000 x 1000 array size implies 1 million independent waveguides for addressing the array. Is that the program intent?

A48. As discussed in the test and evalua on sec on, the BAA states that the performance of the array can be evaluated by employing daisy-chained structures and sta s cal methods.

Q49. Does the program target specific DoD applica ons?

A49. The HAPPI program will develop founda onal technology capable of transi oning to follow-on applica on-specific R&D. While discussion of DoD applica ons is encouraged, it is not required beyond addressing the BAA, Sec on II: Evalua on Criteria, Poten al Contribu on and Relevance to the DARPA Mission.

Q50. Can amplifica on be used to offset some of the losses for a net loss of 1 dB?

A50. No.

Q51. Can we propose rou ng devices requiring electrical actua on, and therefore, electrical connec on?

A51. Yes. See, also A34 discussing power consump on.

Q52. If the university is not allowed to lead the proposal due to non-fundamental aspect of the BAA, is the university at least allowed to submit a proposal abstract and then have an industry partner to lead the proposal?

A52. There is no restric on on universi es to submit Abstracts and Proposals. “Non-fundamental research” refers to publica on restric ons only. It is en rely in the university discre on if they would par cipate.

Q53. In the BAA and at today’s presenta on, both 90 degree and non-90 degree rounding layouts were shown. Are we required to do both, or can we do one of them so long as we can meet the milestones?

A53. No. Demonstra ng one or the other is sufficient as long as the solu on meets the metrics.

Q54. How does the performer prove that the process to create the optical link is compatible with an active platform?

A54. The performer is not required to demonstrate active components, but the compatibility should be thoroughly described using supporting evidence.

Q55. Where can we find the Proposers Day presenta ons and Q&A?

A55. The slides presented as well as video recordings of the Gov. session will be made available at www.darpa.mil/work-with-us/opportuni es.

The Q&A (this document) is available at the sam.gov website along with the HAPPI BAA and will be updated on a regular basis un l the ques on period closes on October 22, 2024.

Q56. Can a proposing team propose to conduct fundamental research led by a university in Phase I and to conduct non-fundamental research and commercial transi on led by a company in Phase II?

A56. No. Non-fundamental research refers to both program phases. Furthermore, the prime organiza on cannot be changed between phases.

Q57. The example provided in the BAA for integrated 3D interconnects outlines a PIC integrated on an interposer, appearing to represent a 2.5D integra on scheme. Is full 3D integra on, bypassing the interposer and using 3D interconnects, within the scope of the HAPPI program?

A57. Yes, 3D integra on and direct chip-to-chip coupling are within scope.

Q58. For the 3D photonic rou ng “obstacle course” pinout maps(s), can you clarify what is considered a “node”? Is it expected that there is a source or detector or some other structure at the nodes?

A58. A “node” can be interpreted as a “loca on” on the map. Sources or detectors are not required at the nodes. The intent is to demonstrate rou ng networks of high complexity.

Q59. For the 3D photonic rou ng “obstacle course” pinout maps(s), are nodes defined only on the first and last layers, or can nodes be defined on any/all layers?

A59. Each link in the obstacle course will consist of a guided op cal path origina ng in the waveguide fabric of one discrete chip and termina ng in the waveguide fabric of another discrete chip stacked on the ini al chip.

Q60. Since A19 in the FAQ states that reconfigurability is not required, does this imply that the fabricated 3D photonic system is intended to have sta c interconnec ons as defined in the pinout?

A60. Yes.

Q61. Is the automated tes ng in Phase 2 expected to assess performance of many 1000x1000 arrays, such as across a wafer, or just within a single 1000x1000 array?

A61. Tes ng a single array will sa sfy the program requirement. Tes ng across the wafer to assess the uniformity and yield of the pla orm is desirable, but not required.

Q62. Is there a requirement for representa ve or total sampling for tes ng of link arrays?

A62. In both phases, the metrics should be reported as typical performance across the array obtained by uniform sampling and sta s cal analysis.

Q63. Does the program metrics for link array size suggest that for Phase 1, that an array pitch of ≤ 300 µm will be acceptable (10 x 10 array in an array area of 3 mm x 3 mm)?

A63. Yes.

Q64. The adjacent link crosstalk metric states that it would be measured at a 3 µm x 3 µm pitch, but this would be limited by the link array size/pitch achieved in Phase 1 and Phase 2. Should this pitch be scaled to the 10x10 array size in Phase 1 and 1000x1000 array size in Phase 2 for a 3 mm x 3 mm area?

A64. In Phase 1, the adjacent link crosstalk can be measured in a smaller separate array with a 3 µm x 3 µm pitch. In Phase 2, it will be measured in the 1000x1000 array.

Q65. Can an organiza on submit mul ple proposals?

A65. Yes, the BAA does not restrict the number of proposals per organiza on. A42 above has been corrected. An amended version of the Proposers Day slides will be made available.

Q66. The metric for the minimum number of rou ng layer implies that PICs may have two or more rou ng layers. Do the interconnects within a PIC also have to meet the Table 1 metrics for link efficiency, array size and area, crosstalk, op cal power handling, spectral bandwidth and opera ng environment?

A66. Yes.

Q67. In the BAA, Table 1, a minimum number of >4 seems to imply at least 5 layers. The FAQ implies at least 4 layers. Can you please clarify which is the correct interpreta on?

A67. The minimum number of layers is ≥4. The BAA, Table 1 has been amended to reflect the clarifica on. Please see Amendment 2.

Q68. What size of die are required?

A68. The minimum die size is 3 mm x 3 mm capable of accommoda ng the 1000 x 1000 Phase 2 array. The BAA does not specify maximum die size. Approaches that can address die-to-die, die-to-wafer, or wafer-to-wafer manufacturing flows are of significant interest.

Q69. Is it a requirement to stack more than 2 chips ver cally?

A69. For demonstra on on the program, only two chips are required to be stacked. Approaches that enable the stacking of more than 2 chips are highly encouraged.

Q70. Does the out-of-plane waveguide need to traverse the substrate of one of the component photonic chips?

A70. Per the BAA, the out-of-plane waveguide traverses the photonic circuit substrate. Please, reference BAA pg. 6, Sec on B. Program Descrip on, pg. 7, Sec on C. Program Structure, and Table 1, Program Metrics. The vision is also illustrated no onally in Fig. 2 on pg. 6. The out-of-plane waveguide purpose is to traverse the thickness of op cal components (PIC or interposer) and enable out-of-plane rou ng through the substrates thickness.

Q71. Would like clarifica on around A achment I Proposer Checklist that is a listed requirement. Do subawards need to complete and include this document as part of the subaward cost proposal?

A71. Sec on 9 of A achment D outlines what is required of the subaward cost proposal. It should also be noted that all subawardees should provide an A achment E with their cost proposal as well. That being said, since A achment I is not listed as a requirement to the subawardee cost, it is not required.

Q72. The presenta on slides state that offerors must include a data rights cer fica on. Is this sa sfied by Sec on 10 of the Volume 1 template? Or is the data rights cer fica on expected to be a separate statement?

A72. Sec on 10 of A achment C does in fact sa sfy this requirement.

Q73. The Volume 1 template calls for a "transmi al le er." Is the transmi al le er expected to be a basic cover le er? I'm not sure I've heard the term transmi al le er, so I just wanted to make sure I'm understanding what that would consist of.

A73. The transmi al le er should iden fy the BAA number, the proposal by name, and the proposal reference number (if any), and should be signed by an individual who is authorized to submit proposals to the Government.

Q74. Is it acceptable to DARPA for an prime organiza on to submit a Research OT proposal without cost share, considering the organiza on does not intend to have any commercial applica ons?

A74. If requested a research OT under 10 U.S.C. 4021, resource share is required and to the maximum extent prac cable, the funds from the Government do not exceed the total amount provided by the other par es.

Q75. Why is A achment J: HAPPI Controlled Unclassified Informa on Guide signed September 12, 2024 deleted from the SAM.gov website?

A75. A achment J is s ll live on sam.gov.

Q76. Is A achment F required? It states only for Other Transac on Agreements. If we would like a procurement contract, do we complete Sec on K Reps and Cert and Other Statements of Offerors for procurement contracts? If we would like an OTA, would we complete a achment F? Or is A achment F required regardless of the type of agreement we request?

A76. A achment F: Other Transac on Cer fica on Template is only required for submissions reques ng an award of an Other Transac on.

Q77. Would you be able to provide or direct me to a sample model contract that I could review as part of the proposal process?

A77. We do not have a sample model contract to offer at the moment.

Q78. Is a cover/ tle slide included in the 20 slide limit for the oral presenta on briefing?

A78. As this is not specified in the BAA, it is recommended that proposers ensure their presenta on does not exceed the slide limit outlined in A achment C.

Q79. Are there any limita ons to the number of presenters/team members present (for prime and subcontractor organiza ons) for Oral Presenta on and Q&A?

A79. The BAA does not limit the amount of presenters or the amount of team members present for the oral presenta on.

Q80. Does the Volume II sec on "Cost Summary" require any in-document content, or is a aching the cost spreadsheet sufficient?

A80. The informa on required from the DARPA Excel Cost Spreadsheet suffices what is requested in the "Cost Summary" sec on.

Q81. Can you confirm that Volume II sec on "Cost Details" is reques ng a table with the aggregated amounts from all team members? Or, is this a per-awardee item?

A81. A achment D of the HAPPI BAA states a proposer must “Provide the cost details broken down by the following (referencing sec ons 1-12). Include suppor ng documenta on describing the method used to es mate costs…” While a table with aggregated amounts may be a way to display this informa on, it is not specifically required.

Q82. Can you confirm that the Cost Spreadsheet for the Prime awardee does NOT need to include amounts from subawardees?

A82. The DARPA Excel Cost spreadsheet does have sec ons that request a breakdown of the subawardee costs.