Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics 
|
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 |
Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics
|
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. |
|
Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics
|
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 |
|
Telescope for compressors and ThomX, posted by Loïc Amoudry at Optical room about lasers and optics
|
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). |
|
ThomX Locked with CVBGs, posted by Loïc Amoudry at Optical room about lasers and optics
|
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 |
|
Powerup with 2.5ps pulses, posted by Loïc Amoudry at Optical room about lasers and optics
|
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. |
|
Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics
|
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 |
|
Optical spectrum analyzer resolution, posted by Ronic Chiche at Optical room about lasers and optics
|
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 |
|
Optical spectrum analyzer resolution, posted by Ronic Chiche at Optical room about lasers and optics
|
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 |
|
Optical spectrum before and after CVBG, posted by Ronic Chiche at Optical room about lasers and optics
|
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. |
|
Amplifier laser diodes issue, posted by Ronic Chiche at Optical room about lasers and optics
|
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. |
|
Pointing stability with CVBG, posted by Ronic Chiche at Optical room about lasers and optics
|
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. |
|
Finesse measurement after confinement, posted by Loïc Amoudry at Optical room about lasers and optics
|
After 3 months without human presence, finesse has been measured 3 times with average optimization:
- 16150
- 16067 |
|
Finesse measurement after the Edge installation, posted by Ronic Chiche at Optical room about lasers and optics
|
After the Edge installation inside the cavity, the Finesse has been measured several times by modulation technique with an average around 16000:
(the scan speed is 50kHz in 10 seconds.)
So, it hasn't changed since the last measurement in June, just before the Edge installation. |
|
Coating reflectivity, posted by Loïc Amoudry at Optical room about lasers and optics 6x
|
| Coatings reflectivity curves and datas for HR Saphir, HR Suprasil and HR ULE. |
|
Beam size and finesse, posted by Loïc Amoudry at Optical room about lasers and optics
|
Measurement behind P4 (planar mirror)
Loïc
Amoudry wrote:
FSR initiale : 33.34 MHz (S3 = -825000 et S4 = -825000) |
|
Onefive ouput power and spectrum, posted by Loïc Amoudry at Optical room about lasers and optics
|
After turning on, one can see the 133.33MHz Onefive output power for ~40min with OD2 filter (~/20). So the real output power is ~57mW. A measurment over
several days (15?) should come in few weeks.
The spectrum here has been taken one day after turning on the Onefive (see Fig. 133_spectrum_full and 133_spectrum). One can see the central |
|
Onefive ouput power and spectrum, posted by Loïc Amoudry at Optical room about lasers and optics
|
1) Note: The OneFive laser used for experimenting is the one for the SBox
but, for now only this laser arrived from the company so we are doing tests (measuring the spectrometer and power ) on it inside the ThomX cavity
clean room. |
|
Alignment procedure, posted by Ronic Chiche at Optical room about mechanics | lasers and optics
|
Picture of the installed mirrors inside the FP cavity.
To install an Iris instead of a mirror :
One has to remove manually the orange nuts and replace the mirror mount with the Iris mount. |
|
33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics
|
On the 8th of July, the SN2439 33MHz laser was returned from NKT to our lab, being repaired.
it stayed all the weekend to warm up in the optical room and has been turned on on Monday.
the mode-locking was not working (28mW output power and a CW line for the optical spectrum), thus I "kicked" the laser with 100µm |