Responses_to_Questions.pdf

TITLE: - Amplified Ultrafast Laser System

SOLICITATION NUMBER: SB1341-15-RQ-0434

RESPONSES TO QUESTIONS

1. A CW optically pumped semiconductor or diode pumped solid state based pump laser capable of producing at least 6 W of 532 nm to pump the Ti:sapphire oscillator.

a. If we can provide the specifications (more efficiently using <6W) does the pump laser have to be 6W?

Response: If every specification for each system component can be met, pump power of < 6 W is acceptable. Please see Amendment 001 for the revised specification.

2. Ti:sapphire femtosecond oscillator capable of producing <7 fsec pulses at a center wavelength of 800nm with >6 nJ energy per pulse at a repetition rate of ≤75 MHz.

a. Although short pulses have a benefit, is <=7fs a necessary requirement? Please let me know if

12fs is sufficient or, if not, why the experiment requires this unique pulse width.

Response: <= 7 fsec is a necessary requirement. The experiments do not require a “unique” pulse width but rather short pulse width enabling new measurement developments. Shorter pulse widths correspond to larger bandwidth and higher peak power, thereby allowing capabilities not possible with longer pulses. The system is being purchased for a broad range of experiments developing capabilities that are either simply not possible or inefficient with pulses that are longer. The intended applications include far-IR generation with extremely large bandwidths, pump-probe spectroscopy to study phenomena that occur on <10 fsec time scales, photoelectron emission spectroscopy, higher harmonic generation, and novel radiation pressure driven time-of-flight optomechanical experiments.

b. Is <=75MHz a necessary requirement or is there some latitude with repetition rate, such as +/-

5MHz?

Response: There is a latitude with the repetition rates, and the variation of +/- 5MHz around 75

MHz is acceptable.

NOTE: The rate “<=75MHz” is currently referred to 6 (six) times in the Solicitation. It should be changed to “75MHz+/- 5MHz” throughout the RFQ. Please see Amendment 001 for the revised specification indicated throughout the RFQ.

3. Q-switched intra-cavity frequency-doubled Nd:YLF pump laser capable of producing ≥50W (at

527nm) pulses at 1 kHz to pump the Ti:sapphire amplifier.

a. If the amplified pulse energy of 5mJ at 1kHz can be met with lower power (<30W), is this more efficient design allowed?

Response: If every specification for each component (including amplifier, CEP stability, OPA, pulse-compressor etc.) can be met, smaller pump power is acceptable. Please see Amendment 001 for the revised specification.

4. Femtosecond Ti:sapphire optical amplifier capable of producing <20 fsec pulses at a center wavelength of 800 nm with >5 mJ energy per pulse at a repetition rate of ≥1 kHz.

a. Would <25 fsec be acceptable? If not, would you please share what you can about the effects on the research using 25 fsec compared to 20 fsec?

Response: <= 20 fsec is a necessary requirement. Shorter pulse widths correspond to larger bandwidth and higher peak power, thereby allowing capabilities not possible with longer pulses.

The system is being purchased for a broad range of experiments developing capabilities that are simply either not possible or inefficient with pulses that are longer.

b. Is there any interest/preference for a system that can produce higher pulse energies than the specified 5mJ?

Response: The specification states “>5 mJ” implying higher pulse energies are acceptable given that every specification in the solicitation is met.

5. The output pulse durations from the femtosecond amplifier in the base system shall be tunable from <20 fsec to <30 fsec using an in-built computer controlled acousto-optic programmable dispersive filter, with a commensurate change in bandwidth.

a. If there are other proven ways to accomplish this, is this acceptable?

Response: If every specification for each component (including amplifier, CEP stability, OPA, pulse-compressor etc.) can be met, an alternate integrated approach is acceptable. Please see

Amendment 001 for the revised specification.

b. Do you mean pulses between 20-30fs? If not, would you please restate what you require?

Response: The pulse duration from the amplifier should be tunable from <20 fsec to <30 fsec using a built-in integrated controller. <20 fsec pulses from the amplifier are needed to achieve larger bandwidth and higher peak power for experiments requiring amplifier pulses. <30 fsec amplifier pulses are needed to achieve higher conversion efficiency while using it to pump the OPA.

6. The beam pointing of the output beam from the femtosecond amplifier should be actively stabilized for subsequent pumping of an optical parametric amplifier or a hollow-fiber pulse compressor.

a. Beam pointing stability from a well-designed amplifier will meet or beat any beam pointing stability specifications for the amplifier. If the pointing specification can be met, is it necessary to have active beam pointing control to achieve stable, low noise pumping of an OPA? What beam pointing stability is required?

Response: The amplifier output is intended to be used: (a) directly in experiments, (b) to pump the

OPA and (c) to pump the pulse compressor. Active beam stabilization system for (b) and (c) minimizes manual realignment when switching between the three options. The required beam pointing stability is: < 10 μrad rms at full beam diameter for all the three cases. While a “well designed” amplifier can meet the beam pointing stability required here, it is unclear if the stability can be maintained over long periods of time without manual intervention. Please see Amendment

001 for the revised specification.

b. Are there requirements on pulse energy stability, since this stability might directly affect both

OPA output noise and CEP noise?

Response: The amplifier pulse energy stability should be <1.5 % rms over a period of 24 hrs.

Please see Amendment 001 for the revised specification.

7. Hollow fiber compressor: If there are other proven ways to achieve the compression of a 5mJ pulse, is this acceptable?

Response: In order for any another pulse compression technique to be acceptable, NIST requires:

(a) The new system/technique to meet every specification in this solicitation.

(b) The new system/technique to be able to temporally compress the output pulse width of the femtosecond amplifier from <20 fsec or <30 fsec to < 7 fsec. The pulse-compressor system shall be capable of accepting input pulse energies >5 mJ at ≥1 kHz repetition rate at a center wavelength of 800 nm from a femtosecond amplifier.

(c) The offeror shall meet all the requirements in the Past Experience factor including demonstration of the extent to which they have recently manufactured and/or distributed similar equipment.

8. CEP stabilization module for the oscillator shall include the capability to stabilize the carrier envelope offset frequency to zero.

a. Is it acceptable if the oscillator for the amplified system stabilizes the offset frequency to frep/4

(20MHz) if the amplifier has locking offset frequency to zero?

Response: Not acceptable.

9. The CEP module for the oscillator shall be capable of accepting input pulse-widths of <7 fsec and input pulse energies up to 7 nJ at ≤ 75 MHz repetition rate at a center wavelength of 800 nm.

a. Is 80MHz acceptable?

Response: Acceptable. Please see Amendment 001 for the revised specification.

b. Is sub-12 fsec acceptable?

Response: Not acceptable.

10. There are CEP specifications required for both the amp and oscillator but no mention of environmental conditions, such as temperature stability and acoustic noise, which have a direct influence on CEP performance. What is required?

Response: Vendor is expected to provide the “temperature stability and acoustic noise” requirements for the lab to be able to achieve the CEP specifications as required in this solicitation.

“Page 5: Installation, (d): The vendor shall provide a list of installation and facility requirements

(with explanations and technical drawings, wherever necessary) including in-house services, temperature, humidity and vibration requirements within one week after an award is made. NIST will provide any required connections to the in-house services.”

11. If all specifications can be met, is a shorter lead time given any preference? Nine months is significantly longer than what is necessary.

Response: No preference for shorter lead time.