Examples of Investigations and Measurments

Basics
In optics, frequency doubling is introduced as a parametric process for which the parameters like phase matching and high non-linearity of the crystal are discussed under the aspect of getting a high conversion ratio. It will be shown that the phase matching condition with the used KTP - crystal can be fulfilled in a convenient way.
This set-up uses for the generation of the fundamental radiation the same Nd:YAG laser as within the EXP-08. Therefore all therein described measurements can be performed as well.

Output power of the Nd:YAG laser
Although a high reflectivity has been chosen for the resonator mirror (R>99.98%) about 10 to 20 mW of fundamental wave power (1064 nm) are transmitted to the outside of the resonator. If 0,5 % is accounted for the total losses, there will be 4 Watt as the fundamental wave power within the resonator. The photo detector is connected to the Y-channel and the injection current (respectively the power of the diodelaser) to the X-channel of the oscilloscope. Each modification of the parameters like temperature (wavelength of the diodelaser) or state of adjustment of the resonator mirror can directly be studied.

Power of the frequency-doubled radiation
By means of the filter BG39, which is placed in front of the photo detector, the frequency-doubled radiation is measured. This filter suppresses the pump as well as fundamental laser radiation. A dynamic track of the measured values is obtained on the oscilloscope in the same way as in the previous example. In an illustrative way, the quadratic relation between the power of the harmonic wave and the power of the fundamental wave becomes evident. Depending on the state of adjustment and the cleanliness of the optical components, up to 3 mW (multimode) of ��green�� power can be generated.