In this part of the lab, the characteristics of the pump diode for the DPSS target design laser are determined. These parameters (spectrum and wavelength characteristics) will be used as the input for a convolution simulation (in the same manner as described in section 5.7 of Laser Modeling) predicting the effect of diode temperature on DPSS laser output.
Using the same AL0808F2000 diode as lab #2, operate the diode at a constant current of 2.2A.
Set the temperature for 10C and enable the temperature controller. Next, switch the diode power supply on and operate it at a constant current of 2.2A. Direct the into a fiber and then into an OSA. Adjust the fiber until the spectrum of the pump diode is seen around 808nm.
When the temperature of the TEC has stabilized, capture the spectrum of the pump diode as well as the peak wavelength of the spectrum. The spectrum must be captured at a resolution of 0.2nm - output values will be in units of dBm which may then be converted into linear units (e.g. mW).
Observe the peak wavelength of the output spectrum at 10C, 15C, 20C, 25C, and 30C and capture the actual output spectrum (every 0.2nm) at 10C, 20C, and 30C). As temperature increases we expect to see the wavelength shift to longer values but hopefully the spectrum remains relatively constant.
Complete a simulation as per discussed in the lecture. The absorption spectrum of Nd:YAG is required - one source of absorption data is the Laser Database from Nasa Langley Research Center . Ensure you have values every 0.2nm to produce a table of data as a starting-point.
Complete a Simulation (using the convolution technique) predicting how pump diode wavelength shift will affect Nd:YAG DPSS output based solely on absorption of the pump radiation. Assume a diode with the spectrum as determined in the lab (i.e. those power values you digitized at intervals of 0.2nm). Produce the following:
Hand In a WORD PROCESSED (not handwritten) lab assignment as follows. Put each question on a new page and ensure each page has a title "Question 1", "Question 2", etc. Also, please ensure the lab report is in a folder for submission (no loose pages).
To be done individually ...