Optimization and stabilization of external cavity diode laser with a constant output beam direction
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Date
2014-09-25
Authors
Ngeno, Kipkirui Paul
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Tunable external cavity diode lasers has shown strong potential for various applications
that require a high precision level than free running, commercially available diode lasers.
Diode laser are better sources when power characteristic are important but not spectral
properties. They operate in multimode, have broad line width for continuous wave (CW)
laser, difficult to give specific wavelength since they are tuned by varying temperatures
and current and suffer from mode hops. These spectral properties are undesirable in
application areas where stability, durability, beam quality, tuning speed and range are
vital. Researchers findings have shown that free running diode laser are sensitive to
optical feedback. This idea is employed in this study where a compact external cavity
diode laser adopting Littrow configuration shall be designed and implemented. The
external cavity is wavelength selective. It is used to externally impose the desired
wavelength. The external cavity consists of diode laser whose one facet is coated with
antireflection (AR), a diffraction grating and a high quality optical mirror. The facet of
the diode without antireflection CAR) coating increases the loss of the internal cavity, thus
raising the threshold level required for lasing to start. The internal cavity is therefore
prevented from lasing. The diffraction grating is used to provide an optical feedback to
the diode laser. The grating splits an incident beam from the diode laser into diffraction
orders such that the first order is reflected back to the laser diode while the zeroth order
forms the output beam. Tuning will be achieved by controlling the angle of grating. The
optical flat mirror allows tuning to be done without changing the direction of the output
beam. Laser drive electronics will be designed to electrically pump the diode laser.
Description
school of Pure and Applied Sciences