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The Laser Laboratory The Physics Department laser lab at Wake Forest University has several pulsed laser sources covering the optical spectrum. The main workhorse is the argon pumped femtosecond Ti:Sapphire laser (Coherent Mira) that can produce <100 fs pulses at 76 MHz from 800 to 900 nm with an average power of >700 mW. Part of the output is used to seed a chirped pulse amplifier (Positive Light) which is pumped by a Q-switched and doubled Nd:YAG laser at 10 Hz. The amplifier has two stages; a regenerative stage and a double pass, linear stage. Typically it can produce 200 fs, 3-4 mJ pulses at the seed wavelength. The output of the amplifier can be frequency doubled or tripled or can be used to generate a continuum from 400 nm to 1600 nm. The modelocked Nd:YAG laser pulses are compressed and frequency doubled to produce 3 ps pulses at 80 MHz with an average power of 500 mW. This output can be used to sync-pump a dye laser to generate 500 fs pulses tunable between 580 and 650 nm with Rhodamine 590 or between 650 and 720 nm with DCM. Further compression to 90 fs or cavity dumping for higher peak powers is also possible. We also have an excimer laser for routine UV spectroscopy and pulsed laser deposition. It is currently used with XeCl for 308 nm operation. Recently, AMP (part of Tyco) donated a commercial pulsed laser laser deposition system with a Lambda Physik LPX210 Excimer laser (248 and 193 nm). The system is now used to grow ZnO films. For time resolved spectroscopy from tens of picoseconds to milliseconds, we use a streak camera (Hamamtsu C2830). Coupled with a monochromator and CCD camera, it is an effective tool between 300 nm to 800 nm. We also have access to the Zeiss LSM 510 confocal microscope at the WFU Medical School. We have integrated our sync-pumped dye laser into the system for multiphoton microscopy of ZnO and GaN samples. On the experimental side, we have a permanent setup for ultrafast white light continuum pump-probe spectroscopy where we can investigate carrier dynamics using a white light continuum from 400 nm to 1600 nm. A sputtering chamber allows us to grow ZnO thin films. The photoelectron emission spectroscopy setup is used to investigate surface defect states in various materials.
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