JTK Notebook

To Do

Short Term

• Make presentation on Ti:sapph lasers for group meeting
• Modify diode mount for water cooling (almost done, will drill screw holes once water blocks get here)
• Build crystal mount (aluminum part done, ordered copper part from eMachineShop)
• Write Gaussian Beam Mode Matching v4
• Get more info from Lambda re: mirrors - transmittance at blue, revised quote (10 mirrors, 2 R=10 curved, 2 R=7.5 curved, 4 flat, 99% output coupler, 98% output coupler)
• Make TEC controller wire for crystal TEC
• Do absorption measurements on our Ti:sapph crystal

Long Term

• Assemble Ti:sapph laser
• Build box for Ti:sapph laser

Theory

• Find some accessible Raman theory writeups
• Work through Raman System Effective Hamiltonian calculations

To Buy

• Water chiller accessories (tubing, etc.)
• Ti:sapph cavity mirrors
• Ti:sapph cavity saturable absorber
• Ti:sapph extracavity optics
• Blue optics (cylindrical-lens telescope, focusing lens)
• FS prism pair

Log

7/16/2015

• Talked about final mirror order with Deniz. Decided on 10 mirrors (2 R = 10 cm curved, 2 R = 7.5 cm curved, 4 flat, 99% output coupler, 98% output coupler). Emailed Lambda for another quote request and with a few more questions (not that they've responded to my last email...). Definitely need to know what they mean by "high reflectance" - we want to minimize cavity losses to make the laser more efficient. The diode pumping papers I'm working off quote 0.7% cavity losses (Finesse is around 900).
• Emailed ECI for the revised quote as well. I imagine it will be very expensive.
• Completed NSF RCR training.
• Emailed Reflekron about a SESAM.
• Started writing Gaussian Beam Tools v4.0

7/15/2015

• Found a stable Z cavity with a folding angle of 10 degrees, a total length of about a meter, and plenty of stability room to move the FS prisms around in. Will require tuning once it's operating to get the crystal and prisms positioned right. Need a way to do an interferometric measurement of the pulses to analyze the GVD compensation?
• Incidentally, fixed (all of?) the KeyError problems by naively upscaling all the units (so that it's not working with such small floats all the time) and adding the keys to the position list. There's now a small problem where, in a cavity, it's possible that the endpoint of the position list will not be exactly where you wanted it to be, throwing off the symmetry of the calculation. Increasing the unit upscaling seems to help. Also, wrote a neat waist detection algorithm. Now have to rewrite a bunch of older code to use that. Maybe just save it for v4...

7/13/2015

• Emailed Lambda back with more questions re: mirrors.
• Realized we need to use a Z cavity instead of a bowtie cavity so that we can use a prism pair for GVD (Group Velocity Dispersion) compensation. Started looking at cavity stability and how prism pairs work as GVD compensators.
• Decided I probably need to massage the code a little to avoid running into key errors because of floating points. Will probably recode everything so that it works in tenths of a millimeter as the "base unit" instead of meters, so that everything can be an int. My other thought is to simply add the dictionary keys to the position list - this would effectively decouple the position list resolution from the optical element positions, which would be very nice anyway (it would let you make things like cavity length scans at higher resolution than currently works). Still worried about floating point key errors with that method though. Maybe a combination....

7/10/2015

• Finished Gaussian Beam Tools v3.2, which reimplements existing cavity stability analysis MatLab code.

7/8/2015

• Tried to get some mill time today, but all the machines were full. Not urgent, so I'll let it calm down a little.
• Started making slides for talking about the Ti:sapph laser to the group.
• Watched over David's shoulder while he tried to get the cavity lock behaving better.
• Started writing Gaussian Beam Tools v3.2, which will re-implement my existing cavity analysis MatLab code.

7/7/2015

• Sent out Gaussian Beam Tools v3.1, with fixes for issues running on Mac.

7/6/2015

• Gaussian Beam Tools v3.0 is done. Sent it out. Nick found that there were some problems with running it on Mac. Will fix issues and send out v3.1 tomorrow.

7/2/2015

• Wrote some code to back out q values from measured beam parameters. Mode Matching v2 is basically done now - it replicates all of the functionality of David's code and expands it a bit by letting you use it in a "plotting" mode with no mode matching, and by letting you work with any number of lenses.
• Thinking about v3: replace lenses with optical elements as classes, handle the position rail better (maybe a class of it's own?). Basically use classes to generalize and expand what the code can do.

7/1/2015

• Continued working on Mode Matching v2.
• Heard back from ATF on mirror quote. Order is too small and specialized for them to do...

6/30/2015

• Wrote v2 of the mode matching program from scratch with some new ideas. Worked great on the first try!

6/29/2015

• A bit downtime for the next week and a half while the student shop is closed. Decided to write a program to do mode matching. Wrote v1 today, and it was awful and didn't work at all.
• Ordered the copper part of the crystal mount from eMachineShop. ETA ~3 weeks.

6/25/2015

• Got quote back from ECI - $13000! Way too expensive. Asked them to redo quote without the backs AR-coated to see what that's like. Sent quote request to Lambda.

6/24/2015

• REO got back to me and said they don't do mirror quotes for such small orders. Sent a quote request to ECI.
• ECI got back to me within 30 minutes with questions. Now that's what I call customer support...
• Made aluminum part of crystal mount.
• Haven't heard back from ATF on mirror quote or eMachineShop on copper part. It's not like it's their job or anything....

6/23/2015

• Got in early to do some machining but all three mills were already being used...
• Sent passive-aggressive emails following up on the mirror quotes.
• Got a quote on indium foil. Sent in purchase request.
• Started working through Raman system theory.
• Heard back from Advantech Machining. They won't do such a small job.

6/22/2015

• Ordered TEC, thermistor, and Kapton tape from Thorlabs. Ordered new mount from Newport. Ordered water chiller from eBay. Ordered aluminum from the stock room to make the aluminum part of the crystal mount.
• Asked for a quote on indium foil.
• Asked for quotes on making the copper part of the crystal mount from eMachineShop and Advantech Machining.
• No response on any of the mirror quotes except the questions from Layertec. Will send passive-aggressive emails tomorrow.

6/18/2015

• Realized the whole mounting scheme won't work because the Thorlabs rotation/translation mount is too large. Will rework design tomorrow to use this mount instead. Will likely have to buy more aluminum and copper stock (gdosafjoijforngoasjf). May look into getting the copper part of the mount outsourced - it's going to involve fairly precise machining on a small piece, and the shop will be closed for a week and a half anyway. The aluminum part I'll do next week.

6/17/2015

• Cut channel into diode laser mount. Waiting to drill screw holes until I get the part to see if I need to mill any more out to make it fit.

6/16/2015

• Got questions back from Thomas at Layertec. Sent answers. They're working on a quote.

6/15/2015

• Ordered water blocks from Custom Thermoelectric.
• Ordered rotation/translation mount from Thorlabs.
• Designed channel cut for diode laser water cooling modification. Looks like it should work with no problems...
• Designed crystal mount.
• Ordered crystal mount copper/aluminum stock.

6/11/2015

• Talked to Deniz about lasing direction. Decided we don't need an intracavity isolator for the Ti:sapph laser. The output coupler will provide enough asymmetry to force lasing in the correct direction.
• Sent email to Layertec requesting quote for Ti:sapph cavity mirrors.
• Talked to Zach about design for Ti:sapph crystal mount. Decided on basic design using water block, possibly from Custom Thermoelectric. Crystal should probably be wrapped in thin indium foil for better contact with copper. Also talked about cutting a "channel" out of the diode laser aluminum block to add a similar water block below the TEC.