Counting Atoms

11:00AM - 1:30PM

Today I adjusted the vertical tilt on the grating to lower the mazing threshold of the laser to a minimum.  This stabilized the laser and increased its propensity for single mode states.  I tested this by directing the laser into a fabry-perot interferometer and observed single modes.  After recalibrating the system for maximum output power, I used our wave meter to measure the wavelength of the laser.  To my surprise, the wavelength remained relatively constant around 809nm despite my changing the laser temperature considerably.

I set up new path for another optical coupler and adjusted it to maximum gain from the beam. Then I connected this coupler with another one on “main” table with optical fiber. I used a mirror to properly navigate light into a beam splitter and then to Fabry-Perrot interferometer. Now the system is adjusted so we can observe it’s modes on oscilloscope connected to Fabry-Perrot and also observe it’s wavelength on wavelength meter.

11:00AM - 1:00PM

I got the better power meter and increased the efficiency of the system further.  Then I tried adjusting the vertical tilt on the grating to achieve single mode lazing over a wide power range.  This proved difficult.  I will need some further instruction on how to do this.

I set up a beam-fiber coupler to get maximum power input to oscilloscope. The maximum gain is 11V. Then I attached the optical fibre to the box that measures wavelength and I am ready to adjust the wavelength of laser.

11:00AM - 2:30PM

Through a final tweak of the temperature without the grating I found that the closest stable wavelength I could reach was 811.21nm with a voltmeter reading of .716V.  Next I replaced the grating and got the laser back through the system and into the fiber.  I then adjusted the grating angle till the laser wavelength measured 811.26nm.  The laser should now be nearly ready to fluoresce krypton.

I connected the fiber to the other system (with the krypton tube) and maximized the peaks on the fabry perot interferometer.  The laser is single mode with high peaks on the FP.

I set up a basic path to measure the wavelength of laser. The beam of  light is parallel according to the table and it`s propagation, as approximately 0.5 cm wide line,  is also parallel with table. I tried to measure  the wavelength of laser, but it was not propably focused enough into optical fibre. Another part of experiment was calibrating the temperature. I calibrated the line at every 0.05 volts. I measured both actual and setting voltage and I obtained polynomial functions of volatge/temperature, that describe the behavior with good precision. The graph is here: calibrationoftemperature_jakub

11:00AM-2:00PM

I rotated the copper laser mounting in its box and then rotated the box itself in order to get the laser to shine out of the box and through the system without the grating.  Then I adjusted the mirrors to get the beam into a fiber.  The laser without the grating lazed at ~808nm.  I adjusted the temperature of the laser to change it to 811.15nm.  This requires the laser to run a little hot; the multimeter is reading .721 V.  My next step is to tune the laser with the grating at this temperature.  For the moment I am leaving the laser set up as is, but the box is not screwed down so be careful not to touch it.

This is a test to see how annoying it is to upload data files

fig07-06

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Chain of valves on the atom source