Spherical mirrors at closest position. FSR, finesse and beam size., posted by Loïc Amoudry at Optical room about lasers and optics 
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The spherical mirrors are at the closest position to get a FSR ~=33.3435 MHz. Planar mirrors are at the largest position.
The finesse has been measured about 17 000.
Beam diameter (2*w) is ~= 4.6 mm x and y. |
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Amplifier output power , posted by Loïc Amoudry at Optical room about lasers and optics
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The ouput power of the ThomX amplifier has been measured as a function of the 3rd stage pumps current (0A is 1st and 2nd stage turned on).
We measured the total power, the total power without the "donuts" pump signal dumped by an iris and the transmission of a dichroic
mirror (for ref see image). |
Amplifier output power , posted by Loïc Amoudry at Optical room about lasers and optics
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Loïc
Amoudry wrote:
The ouput power of the ThomX amplifier has been measured as a function |
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Onefive Origami 33MHz specs, posted by Loïc Amoudry at Optical room about lasers and optics
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Beam Size Onefive added
Loïc
Amoudry wrote:
Power during ~20h, power after turn on, spectrum image and excel |
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Onefive output power, posted by Loïc Amoudry at Optical room about lasers and optics
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The pump voltage has been increased few days ago when looking for a modlock of the laser.
The 33MHz Onefive output power is now 3.58mW with OD1 filter ==> ~36mW.
There are 2µW @ 1% coupling fiber with OD1 filter ==> ~20µW ==> 2mW @99% coupling fiber (2mW to the amplifier). |
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CVBG reference and Eric Cormier calculation, posted by Loïc Amoudry at Optical room about lasers and optics
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The Stretcher is the "D 24-02-II", it must be used in double path before the amplifier injection.
There are two compressors in single path, "D 25-14-I" and "D 25-14-II".
Eric calculations are attached below. |
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Onefive output power, posted by Loïc Amoudry at Optical room about lasers and optics
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Onefive output power measured today. 3.52 mW with OD1 filter ==> ~35mW.
Loïc
Amoudry wrote:
The pump voltage has been increased few days ago when looking for |
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Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics
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We installed the 2 CVBG for compression after the amplifier.
We used an interferometric technique with a delay line and combining the two paths in a CCD to measure interferences... see interferences.avi video
file |
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Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics
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Yesterday, Loic installed a telescope before CVBG's to reduce the spot size on CVBG's and reduced the incident angle 0.5-1° on them (on the
datasheet the specified incident angle is 2.8°).
We used an interferometric technique with a delay line and combining the two paths in a CCD to measure interferences. |
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Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics
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Yesterday, Loïc put the CVBG's back to their specified angles.
We used an interferometric technique with a delay line and combining the two paths in a CCD to measure interferences.
After supressing the global shape of the superposed pulses, one measures the amplitude of the remaining fringes (standard deviation) each 50µm |
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Telescope for compressors and ThomX, posted by Loïc Amoudry at Optical room about lasers and optics
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CVBGs telescope is done with w ~= 1mm.
ThomX telescope is done with w ~= 2.3mm in x and y.
Newt step is to lock with these short pulses (measured ~2.5ps with FWHM standard deviation interference method). |
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ThomX Locked with CVBGs, posted by Loïc Amoudry at Optical room about lasers and optics
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ThomX has been locked with a new telescope while using compression CVBGs.
Coupling is ~50-55% and lock is stable.
Power up to ~50kW should follow up soon (stop when HOM are observed). We'll not go over ~100kW to not risk any breakdown due to the |
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Powerup with 2.5ps pulses, posted by Loïc Amoudry at Optical room about lasers and optics
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A power up has been performed on ThomX until 65kW intracavity power. We didn't see any modes but stored power was really unstable since ~60kW (see
image tek00004.png).
Measurement report is shown in the table below. Gain seems to decrease against intracavity power. |
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Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics
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Last Thursday (20th of February), Loïc and Titouan realigned the stretcher CVBG to its nominal angle and they used an interferometric technique
with a delay line and combining the two paths in a CCD to measure interferences.
After supressing the global shape of the superposed pulses, one measures the amplitude of the remaining fringes (standard deviation) each 50µm |
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Optical spectrum analyzer resolution, posted by Ronic Chiche at Optical room about lasers and optics
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The Koheras @0.5mW is directly connected with fibers FC/APC -> FC/PC to the Avantes optical spectrum analyzer.
The FWHM wavelength, measured with the Avantes software, is 0.126nm |
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Optical spectrum analyzer resolution, posted by Ronic Chiche at Optical room about lasers and optics
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Same measurement with Koheras @100mW and using fiber coupling lenses between Koheras and Avantes OSA.
The FWHM wavelength, measured with the Avantes software, is 0.116nm
Ronic |
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Optical spectrum before and after CVBG, posted by Ronic Chiche at Optical room about lasers and optics
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Measurement of the optical spectrum with Avantes OSA before (1st picture) and after CVBG (2nd picture) with 2nd stage on the laser amplifier.
The 1st CVBG stretches the beam horizontally due to the default incident angle and the fact that different wavelength are reflected in the CVBG
with different depth. |
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Amplifier laser diodes issue, posted by Ronic Chiche at Optical room about lasers and optics
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This is a long time issue for the ThomX amplifier : on the 4 pumping diodes available, the 1st diode has a higher temperature than the others around
40°C (see the picture).
the problem comes from the TEC which is not activated (see diodes parameter files in execel format). the related software windows are shaded. |
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Pointing stability with CVBG, posted by Ronic Chiche at Optical room about lasers and optics
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Yesterday, with Titouan, we made some measurements on pointing stability of the laser beam after amplifier and CVBG.
the amplifier beam go through a first telescope to be small enough and colimated before going to CVBG's, then go to CVBG's and then is sent
through the FP-cavity telescope to the FP-cavity itself. |
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Finesse measurement after confinement, posted by Loïc Amoudry at Optical room about lasers and optics
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After 3 months without human presence, finesse has been measured 3 times with average optimization:
- 16150
- 16067 |