285 nm-Laser (S-MOT)

The 285 nm Laser consists of a two-stage frequency doubled, raman-fiber-amplifier MOPA. The raman-fiber-amplifier is seeded by a diode laser.

Laser-Diode current: 280 mA @which settings?

Seed power (is displayed in the FLPM RMU CCT 1.1.0.0 program): ~ 20 mW

Turning on the Laser

Enable oxygen to 285nm SHG.

Enable main-switch. Now set the key to standby.

Wait for the LED to change the color from orange to green to orange (~15 seconds after turning on). Turn the key now.

Start the program FLPM RMU CCT 1.1.0.0 and select the checkbox of Laser Enable.

The Power Setpoint must stay at 0.500 W

Optimize fiber coupling to Iodine Spectroscopy. Transfer-efficiency > 70%

Change Power Setpoint for 285nm SHG operation

2 - 2.500 W for 100-150 mW directly after 285 nm SHG.

Do not exceed much more than 3.5 W

Turning off the Laser

Unlock the laser in DigiLock

Now just turn off the main-power on the laser

Disable oxygen to 285nm SHG.

Locking to Iodine-Spectroscopy

Start DigiLock-Module Server and connect to S-MOT-Laser

Push Scan on and AutoLock

Change the Offset Value to 0 V

Change the frequency with the piezo on the toptica rack electronics to be close to the iodine resonance (check with wavemeter)

Change the Setpoint (under AutoLock) to be in the middle of the error signal. Check, if the crosshair snaps to the slope.

Move the crosshair to the second slope, rightclick on press PID: Lock to Slop.

Lasersystem - Typical power values

The 285nm SHG was build by Jan Friebe and is described in his diplomathesis.

570 nm-Laser

Outputpower after cube to 285 nm-SHG: ~ 1.2 W @ 2.5 W 1140nm pump

Operationpower: < @ 3 W

Max outpupower: ??? W @ ??? W

Iodine spectroscopy

500 mW pump of the yellow laser

Infront fiber: ~ 38 mW

After fiber: ~ 29 mW @ 0.500 W (= 400 mV @ 0.500 W) [efficiency ~ 70 %]

Normal operation (2-3 W)

After fiber: ~ 100 mW

At iodine cell: 20-40 mW

285 nm-SHG

Outputpower: ~ 100+ mW @ 2.000 W

Stabilized power (infront AOM): 80-90 mW

Power behind the AOM: 43 mW @ 2.000 W (efficiency ~ 50 %)

Power for the Zeaman-slower: 10 mW

Power behind the mystical mirrow: 30 mW