HYPERSPECTRAL LASERS FOR SPECTROSCOPIC MEASUREMENTS IN THE NEAR-INFRARED
Date
2009-06-24Author
Kraetschmer, Thilo
Advisor(s)
Sanders, Scott T.
Metadata
Show full item recordAbstract
This project develops hyperspectral lasers that are built using fiber-optic cavities and
broadband semiconductor gain media. These sources are custom designed for high-speed
(typically 30 kHz) spectroscopic sensing applications, such as thermometry based on H2O
absorption spectroscopy in harsh, combusting environments that are generally not conducive
to more conventional thermometry techniques.
Novel time- and frequency-division multiplexed lasers are introduced that either scan
continuously over chosen wavelength ranges or switch among discrete wavelengths. One
example is a laser that scans through a 0.1-4 nm range centered near 1350 nm every 10 ?s; it
is an advanced Fourier domain mode locked (FDML) laser that offers ultra low intensity
noise and a significantly narrowed spectral linewidth compared to typical FDML
performance. Another example is a discrete time-division multiplexed laser that cycles
through 19 spectrally narrow wavelengths in a 44-nm-wide spectral band (1333?1377 nm)
every 15 ?s, where each wavelength can be aligned to a specific absorption feature.
Such engineered lasers are changing the way one looks at solving spectroscopic sensing
problems as these sources can be custom designed to address a particular problem instead of
making decisions based on the availability of light sources in the marketplace.