Experiment 04 - advance Laser Lab - آزمایشگاه بین المللی چمران

Experiment 04 - advance Laser Lab

Diode Laser

Experiment

Set-Up

Description of Module

Module A
Module B
Module C
Module D
Module E
Module F
Module G
Module

Spatial Beam Distribution

With the above set-up the Beam geometry of the laser diode will be measured. The Module A (Laser diode with tow axes rotational stage) and the photo detector (Module G) are used. In front of the detector a pinhole mounted in a click mount is inserted into the mounting plate.

The laser diode can be turned around its optical axis as well perpendicular to it. Turning the diode around its optical axis is provided to align the diodes elliptical beam cross section with respect to the plane of the other rotational stage. By rotating this stage the angle resolved intensity distribution of the laser diode emission is been measured.

The photo detector is connected to the BNC socket at the rear of the control unit the section "INPUTS" marked with "PHOTODIODE". The BNC outlet marked "PHOTODIODE" within the section "OUTPUTS" is connected to the digital voltmeter. The voltmeter is switched to DCV.

One has to make sure, that the detector will not be saturated by the laser light. A pinhole is used to reduce the sensitive area of the detector for better angle resolution as well for avoiding the saturation of the detector.

Of course the detector output of the control unit can also be connected to on oscilloscope. In this case the modulator of the control unit can be activated for producing AC signal.

Within the same set-up the dependence of the laser power versus injection current and temperature can be measured.

In addition the behaviour of the laser diode is measured when it is modulated either by the internal modulator (rectangular amplitude, switch MODULATOR on the front panel is set to the INT. position) or by an external modulator. In the latter case the signal of the modulator is fed into the BNC socket within the section " INPUT" marked as "EXT". MOD." and the switch "MODULATOR" is set to thev"EXT" position.