Characterizing a Violet Diode Laser by Simple Techniques

Lindsey Garay, Oceanside High School

The application of violet laser research and the need to have its
properties well understood and carefully optimized was the focus of this
study.  Investigation of the wavelength variations and the size and
shape of the beam of a violet diode laser were determined through the
use of simple, improvised techniques on a 404 nm violet diode laser.

Violet diode lasers are based on a relatively new GaN (gallium nitride)
semiconductor technology that is projected to replace the current
red-infrared GaAs (gallium arsenide) technology for many applications in
the next decade, especially laser projectors. 

The Model PPMT (Power Technology, Inc.) violet laser was studied to
observe minute wavelength changes over a  20º-30º C operating
temperature range of the laser. The setup used a measured diffraction
grating to observe the laser's pattern, and its measured movement on a
photo detector, to observe wavelength changes. 

Additionally, the beam spot size and shape was studied photographically
at distances ranging up to 55 meters from the laser. These results
compared favorably to a Gaussian beam propagation model that was created
through an Excel spreadsheet program. 

Continued studies of violet diode laser intensity and polarization are
currently underway through the utilization of similar techniques and
equipment. 

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For Long Island Science and Engineering Fair, submitted 12 January 2006