Abstract: |
Laser
systems are used for distance measurement in many different contexts,
from thousands of km down to fraction of micrometers. LIDAR (Light
Detection and Ranging) systems produce an image in two or three
dimensions, or provide in-depth information of particle or molecule
concentration. Laser ranging has been traditionally performed with
pulsed solid state lasers or with low power semiconductor lasers in
the near infrared region. Fuelled by the
development of the optical communication technology, a new generation
of high speed and high power semiconductor lasers in the eye-safe
region of 1.5 µm, has recently come to the stage. These new laser
sources can be used to improve laser ranging systems and techniques.
The
objective of this project is to study, both from a theoretical and an
experimental point of view, advanced semiconductor lasers emitting
around 1.5 µm and their applications in laser ranging systems. The
basic emitter will be a Master Oscillator Power Amplifier (MOPA),
either hybrid or integrated. The hybrid version will be either a high
speed Vertical-Cavity Surface-Emitting Laser (VCSEL) or a
multi-section semiconductor mode-locked laser as seed and an Erbium
Doped Fibre Amplifier (EDFA). The integrated version will be based on
a DFB laser and a tapered semiconductor amplifier.
Different
ranging techniques making use of the advanced semiconductor lasers,
such as time of flight (TOF), CW pseudo-random modulation Lidar,
chaotic Lidar and CW Frequency Modulated Lidar will be investigated.
The dynamic properties of the devices, including polarization issues,
will be investigated theoretically and experimentally. Demo-systems,
including the complete detector and driving/analysis electronics will
be fabricated and used for evaluating the performance of the
different ranging approaches. Different range distances will be
measured.
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