Available Photonics Experiments:

P5861 Diode laser
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  • Basics of semiconductors
  • Types of laser diodes
  • Spatial intensity distribution
  • Spectral properties
  • Polarisation properties
  • Beam shaping
  • Examples of investigations and measurements
OX Spatial intensity distribution
With the above set-up the beam geometry of the laser diode will be measured. The module A (laser diode with two axes rotational stage) and the photo detector (module G) are used.
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.
OX Spectral Properties
The wavelength of a laser diode is determined by the maximum gain and the optical length of its resonator, which in turn depends on the temperature and the optical density inside the resonator relying on the injection current. The goal of this experiment is the measurement of these relations. To determine the wavelength, the Nd:YAG rod with its well known absorption transitions will be used. The rod is mounted into the module E and has a diameter of 3 mm and a length of 5 mm. The beam of the diode laser is focused by means of the module B into the rod. For different temperatures of the laser diode the maximum of absorption will be determined.
OX Polarisation properties
To the set-up the module F is added. The module consists of a rotator with scale for rotating and reading the angle position of the polariser mounted into it. To obtain unambiguous polarisation states with respect to the polarisation analyser the laser light of the diode is collimated by means of the module B containing the focussing optics. The parallelism of the beam is checked with the IR screen and adjusted by the distance of the module B from the diode. The polarisation analyser is turned to a position for a sufficient signal. Now the injection current is varied and the intensity behind the analyser is measured.
OX Beam shaping
From the basics and carried out measurements it is known that the emitted beam of the laser diode exhibits a more or less strong divergence which in addition posses an significant astigmatism. Within this optional experiment different sets of lenses shall be used to correct the beam. Without optics which corrects for these errors, the use of diode lasers is very limited. Applications of laser diodes are only successful if one is able to transform the beam into the desired shape.
For this reason in this experiment three different optical element are used:
module B: microscope objective f=8.2 mm
module C: cylindrical lens f=20 mm
module D: cylindrical lens f=80 mm
  • P5861 Diode laser consisting of:
13L-03901BNC-Banana adapter connection leads 2x4 mm plugs
24B-07301Collimating cylindrical lens f = 20 mm
34B-07401Collimating cylindrical lens f= 80 mm
4ED-00201Digital diode laser controller
5MC-00051Profile rail MG-65, 500 mm
6MC-01201Crossed hair target mounted in holder 25 mm
7PM-00701Infrared display card, spectral range 0.8 -1.6 �m
8TP-00301Digital multimeter 3 1/2 digits
9XM-00201Module A - Diode laser head, adjustment holder
10XM-00301Module B - Collimating optics on carrier MG-65
11XM-00501Module D - Adjustment holder with Nd:YAG rod
12XM-00801Module G - SiPIN photodetector
13XM-01201Rotary polarisation analyzer on carrier 20 mm
14XM-02201Optics cleaning set
15XM-10902Mounting plate C25 with carrier 20 mm
 4D-01001Laser safety goggles 532, 808 and 1064 nm
 TP-01001Oscilloscope 100 MHz digital, two channel