Available Photonics Experiments:

P5865 Q-switch operation (DPSSL) PDF Download page

  • P5862 Nd:YAG laser
  • Q - switch by saturable absorption
  • Puls peak power
  • Width of laser pulse
  • Pulse repetition rate
  • Max repetition rate
  • Average output power
  • Optional active Q-switch
  • Optional mechanical Q-switch
Principle of operation
The basic set-up of XP-06 is enhanced by the saturable absorber module L which is placed into the laser cavity formed by mirror M1 and M2. The initial absorption prevents the laser oscillation. Under increasing induced emission due to the optical pump process the absorption decreases under the threshold of the laser.
  • Examples of investigations and measurements
Characterization of diode pumped Nd:YAG laser
All experiments and measurements performed with XP-06 Nd:YAG laser can be done as well with this setup.
In addition a KTP crystal (K) and the filter BG-39 (F) is provided which turns the XP-06 experiment into a set-up for frequency doubling.

Passive Q-switch
After aligning the basic set-up in the same way as already shown in XP-06 the Q-switch crystal assembly (16) is inserted inside the cavity It can be turned and tilted inside the adjustment holder for highest peak output power. The output is monitored by means of the provided photodetector (14) which is connected to the signal conditioning box (3). The output of this box is connected via the BNC connector to an oscilloscope. As a result of the Q-switch crystal the output shows a train of pulses which peak power and repetition rate depends on the losses like pump efficiency as well as cavity losses.

Mechanical Q-switch
For the demonstration of basic Q-switching the optional mechanical light chopper is applied. Although no real Q-switching is obtained it shows the significant increase of the initial spike indicating the begin of Q-switching.The speed of the chopper blade can be controlled and the effect on the initial spiking determined.
Electrooptical Q-switch
To demonstrate active Q-switch operation the optional Pockels’s cell (22) including the necessary high voltage driver is applied. The cell comes with an adjustable brewster window to set the optimum polarisation parameter. The Pockels's cell is placed inside the cavity. The voltage of the cell is off to align the cavity for maximum output. If the high voltage is applied, the Pockels's cell turns the direction of polarisation in such a way that the losses at the internal Brewster's window entends the threshold and the laser operation is surpressed.
  • P5865 Demonstration of short pulses with saturable absorber consisting of:
13L-02002BNC cable, BNC connector both sides, 1,5 m
2ED-00201Digital controller for injection current and temperature
3ED-00601Photodetector signal conditioning box
4MC-00051Profile rail MG-65, 500 mm
5MC-01201Crossed hair target mounted in holder 25 mm
6PM-00701Infrared display card, range 0.8 -1.6 µm
7PM-02501RG1000 Coloured glass filter 50x50x4 mm
8XM-00201Module A - Diode laser, adjustment holder
9XM-00301Module B - Collimating optics on carrier
10XM-00401Module F - Focussing optics, f=60 mm
11XM-00501Module D - Mirror adjustment holder with Nd:YAG rod
12XM-00601Module E - Adjustment holder “right” with laser mirror SHG 100
13XM-00701Module F - Filter plate holder
14XM-00801Module G - SiPIN photodetector
15XM-01001Module P - Crystal for passive q-switch operation with adjustment holder
16XM-02201Optics cleaning set
Required options:
19TP-01001Oscilloscope 100 MHz digital, two channel
20XM-01101Active Q-switch with Pockels’s cell and HV driver
22XM-08041Mechanical light chopper, intracavity