====== 383 nm Laser system (T-MOT) ======

The 383 nm laser system consists of 767 nm lasers which are then frequency doubled to achieve 383 nm light.

**External Cavity Diode Laser (ECDL)**

For 767 nm lasers, ECDL in Littrow configuration is used. Typically we used the laser diodes from Eagleyard Photonics: EYP-RWE-0790-02000-1500-SOT02-0000

Recently, Eagleyard has replaced these with new laser diodes: EYP-RWE-0760-02010-1500-SOT12-0000

**TA**
  * Output Power: 1.5 W
  * Input Current: 2 A
  * Injection Power: 32 mW
  * Power behind 30dB Isolator: 1.05 W
  * Originally this TA was used: EYP-TPA-0765-01500-3006-CMT03-0000. Is this still true?

**Fiber**
  * PMC-780-5,0-NA012-3-APC-200-P
  * Incoupling: 67%
  * Power behind fiber: 700 mW

===== Frequenzy doubling =====

**LBO-Crystal**
  * Lenght: 15 mm
  * AR coating

**Resonator**
  * Ring resonator (double Z configuration)
  * Length: 280mm
  * Curvature of mirrors: 50 mm (S3 and S4)
  * Distance of mirrors: 64 mm 
  * Waist: 30µm (crystal), 130µm (long arm)
  * Transmission: TS3 = 0.049%, T1 = 1.2 %
  * Conversion efficiency ENL = 6.1*10^(-5)/W
$$E_{NL} = \kappa L_c k_1 h_m (B,\xi) $$
  * Linear losses: eL = 0.85(0.15) %
  * Finesse: F = 270

{{ :groups:mg:experiment:laser:ueberhoeungsresonator_mg.png?400 |}}

===== Stabilisation =====
  * PDH-Method
  * Error signal at about 20 MHz


{{ :groups:mg:experiment:laser:mg_aufbau.png?400 |}}

===== Stabilisation: Laser 4 - Potassium =====
{{ :groups:mg:experiment:laser:image_2022-04-01_110522.png?400|}}
Dopplerfree Saturation Spectroscopy on D1 line of Potassium:

  * 1st the two beams with similar intensity are generated by the beam sampler and are send trough the glas cell
  * one part of the initial beam is going trough the sampler to a double pass aom and then in the other direction trough the glas cell, crossing only one beam. Important: the beam coming from the aom must have a much higher intensity!
  * the first two beams, coming from the sampler trough the cell are than monitored by the PD. The signal is substracted
  * in or case e use the aom to create the peak on one side of the mainpeak. This is important for the lock-in scheme

{{ :groups:mg:experiment:laser:dopplerfreespectrosc.gif?700|}}