Available Photonics Experiments:

P5866 Pulsed diode laser PDF Download page

  • Fundamentals of semiconductor laser
  • Types of pulsed diode laser
  • Peak power of laser pulse
  • Duty cycle
  • Repetition rate of pulses
  • Average output power
  • Spatial radiation distribution
  • Examples of investigations and measurements
Measuring the repetition rate
Measuring the pulse width
Temporal properties
Pulsed diode lasers emit a sequence of short pulses with a pulse width of 50 - 100 nanoseconds. The repetition rate depends on the duty cycle which is typically 0.1 %. Similar to a flash lamp the laser can emit a very high peak power in a short time. This qualifies pulsed diode laser for remote sensing application like LIDAR and range finding. Within this experiment the temporal and spatial properties of a diode laser emitting a peak power of 70 W within a pulse width of 100 ns. The electrical as well as optical pulse is monitored on an digital oscilloscope with USB connection for plotting or saving the measured plots.
OX Spatial energy distribution
As already known from continuous working laser diodes the elliptically shaped emission is strongly divergent. Within this parts of the experiments the spatial intensity distribution is measured by using the photodetector (2) which is mounted onto the swivel arm of the unit (13). The photodetector is connected to a digital meter which is operated in the A mode measuring the photo current of the detector. By turning the swivel arm the angle resolved intensity distribution is recorded.
The laser (7) is mounted into a 4 axes adjustment holder with additional rotary insert so that the laser can be turned around its axis. By means of the scale the rotation angle can be read. Turning the laser to the main axes of the elliptical beam and measure the angle resolved intensity distribution provides three dimensional plot of the emission cross section.
OX Polarisation properties
This experiment shall provide information about the polarisation properties of pulsed diode laser. For this purpose a polarisation analyser (1) is placed onto the swivel arm in front of the photodetector (2). The polarisation extinction is measured for different values of the injection current by rotating the polariser firstly to the maximum and subsequently to the minimum of the transmitted radiation.
OX Collimated radiation
From the measurements of the spatial intensity it is known that for a application the emissions needs to be collimated. This done within this section of the experiments. From the measurements can be concluded what focal length and aperture a lens should have to get an almost parallel beam. The requirements for a short focal length with a large aperture can not be fulfilled by a single lens.
Typically three element collimators are used to obtain the highest collimation and subsequently highest transmission of the divergent light. The provided module B (10) contains such a collimator mounted in a holder which is placed in front of the diode laser. The adjustment screws of the holder of the diode laser are aligned in such a way that the beam passes the collimator centrically.
  • P5866 Pulsed diode laser (XP-0900) consisting of:
12B-05401Photodetector for pivot arm
22E-02901IR converter screen 0.8 - 1.6 �m
33C-00801BNC T - connection piece
43C-02401BNC shunt resistor 50 Ohm
5ED-00901Pulsed laser diode controller PLDC-01
6LS-13001Pulsed diode laser module
7MC-00061Profile Rail OCM 650, 500 mm with ruler
8TP-00301Digital multimeter 3 1/2 digits
9XM-00300Module B - Collimating optics on carrier MG-65
10XM-02101Triple swivel unit
11XM-11141Adjustment holder, 4 axes, rotary insert , C20
 Required Options:  
 TP-01001Oscilloscope 100 MHz digital, two channel
 TP-00421Laser power meter LabMax-TO
 TP-00501 Laser energy sensor head 300 nJ - 600 µJ