6 Chapter 2. First light
ensuresthatthecurrentisrampedupslowlyandsafelytotherequired
current. However,whenfirstaligningthelasertoyourexperiment,itis
important to set the laser output power to a low value for safety.
Adjustthediodecurrentto5–10mAandcheckthatthediodevoltage
(VOLTAGE selectionontheDLC8-waydisplayencoder)isthesameas
listedinthediode datasheet.Ifindoubt, pleasecontactMOGLabsbefore
continuing.
Thelaserthresholdcurrentisdefinedasthecurrentatwhichtheoutputis
1mW.AdjustCURRENT to achieve1mWoutput,andifthe thresholddiffers
from that in the test report by more than 10mA please refer to §4.3.
Abovethreshold,thelaserpowervs. injectioncurrentislinear(seefig-
ure 2.1). Initially the current should be set above threshold, but well
below themaximum operating current, until thelaser is fully alignedwith
your experiment.
2.3 Temperature
TheoptimumtemperaturehasbeensetbyMOGLabsandshouldnotre-
quireadjustment. Oncethediodecurrentisset,allow5minutesforthe
temperaturetoreachequilibrium. Whenthelaserisnotneededforex-
tendedperiods, forexampleovernight, turnthelaser diode off and the
keyswitchtoSTANDBY.Instandbymode, thetemperaturecontroller re-
mains active,sothatstableoperation canbe achievedmorequicklythan
whentheDLCispoweredoff. ItisnotnecessarytochangetheCURRENT
setting when turning the laser diode on and off.
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