Dear all,
I am building and aligning mech Zehnder type f-2f interferometer for CEP signal detection. I have a few questions regarding this setup if someone could advise or comment?
- (crystal length / 2 x ZR) = 2.84 and we can work out the focus spot inside the crystal and focal length of the lens. Since In my case I have low power to use as a pump (10mw), do I need to focus tightly, or follow this condition? (I am using 10mm PPLN crystal)
Thanks in advance!
Dear Dr. Sankari Manda
, thanks for your comment. Actually even with 10mW, I might have reasonable peak power; the difficulty is, I don't know what the pulsewidth is after supercontinuum. Because due to modulational instability, the initial 135 fs pulse breaks up into multiple solitons with different pulse durations.Also, the bandwidth that I want to frequency double (~1400nm/2), corresponds to which soliton in the time domain is unknown. Therefore, I am assuming the pump beam is a CW signal.
Dear Abbas, before I can give some suggestion, can I know what kind of laser oscillators you are working with? Ti:sapphire? Er:fiber?
In my experience, there is no need to use another laser for alignment. I also used a Mech Zehnder type f-2f interferometer. I used a grating to spatially disperse and a APD to detect, as shown in the figure. Right in front of the APD, if you see the beam using a white paper, you will see two beams, one is the SC, the other is the SHG beam. In my case, I used 1200 nm -> 600 nm. I didn't measure the power, but I can clearly see the beam spot of SHG after grating. Then I aligned the spatial overlap of the two beams both in near field and far field. Finally I adjusted the delay, CEP signal could be found. I suggest to use a fan type crystal, that gives you a more flexible choice of SHG wavelength. I think 10-mm long is fine. You can check this paper [OE, 25, 10, 11910, 2017].
I never calculate ZR condition. But I think follow your calculation the result should be right.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Optics