Participants : Marc, Yuefan, Yuhang

Today we continue the alignment of the collimator and the fiber.

Because last time wasn't successful, we decided to use a 1550 nm fiber laser and try to align it at the opposite of its use (inject the laser with the fiber and try to align the output of the collimator).

If we could align it using an IR card, it was not possible to use a power meter nor the beam profiler due to this wavelength.

We decided to go back the first way of aligning this collimator (laser at the input of the collimator and check the power at the output of the fiber).

We decided to use 2 sterring mirrors (actually one mirror and one 98/2 BS).

We got the following power

output of the Auxiliairy laser : 0.873A -> 29.7mW

After 1 mirror + BS (98/2) : 28.7mW

After collimator : 28.7mW

After the fiber 4.5 uW

We can see some light at the output of the fiber (on IR card, power meter and fiber photodiode).

One problem is that as soon as we touch the fiber or the collimator, we see power fluctuations.

This means that between each time we screw we need to wait for few seconds...

It should be useful to find a way to fix the fiber.