In the field of ablative-based material processing there is a desire to use short pulse width (subns) laser sources. If the pulse width is too long <10 ns the processing is fast, but crude. If the pulse width is too short <10 ps the processing is precise, but slow. In an effort to balance the process fidelity with material removal rate, a unique TEM<sub>00</sub> mode quality sub-ns (~0.5 ns nominal pulse width) laser was developed.
Advanced LIDAR applications such as next gen:
Time of Flight (e.g., Satellite Laser Ranging);
Coherent and Incoherent Doppler (e.g., Wind LIDAR);
High Spectral Resolution;
Differential Absorption (DIAL);
photon counting LIDAR (e.g., 3D LIDAR);
are placing more demanding requirements on conventional lasers (e.g., increased rep rates, etc.)
and have inspired the development of new types of laser sources. Today, solid state lasers are
used for wind sensing, 2D laser Radar, 3D scanning and flash LIDAR.
In this paper, we report on the development of compact, highly efficient, high power all-solidstate
diode pulsed pumped ns lasers, as well as, high average power/high pulse energy sub
nanosecond (<1ns) and picosecond (<100ps) lasers for these next gen LIDAR applications.
While conventional Raman Spectroscopy (RS) has predominately used fixed wavelength cw lasers,
advanced Raman spectroscopic techniques such as Stimulated Raman and some types of Raman Imaging
typically need pulsed lasers with sufficient energy to induce the Raman process. In addition, pulsed lasers
are beneficial for the following Raman techniques: Time Resolved Raman (TRR), Resonance Raman (RR),
or non linear Raman techniques, such as Coherent anti-Stokes Raman spectroscopy (CARS). Here the
naturally narrower linewidth of a ns pulse width laser is advantageous to a broader linewidth ultrafast
In this paper, we report on the development of a compact, highly efficient, high power solid-state
Ti: Sapphire laser ideally suited for many Raman spectroscopic techniques. This laser produces nanosecond
pulses at kHz repetition rates with a tunable output wavelength from ~1 micron to ~200 nm and pulse
energies up to 1 mJ. The narrow bandwidth of this laser (<0.1cm<sup>-1</sup>) is ideally suited for applications such as
Laser-induced fluorescence (LIF) measurement of OH free-radicals concentrations, atmospheric LIDAR
and Raman spectroscopy.
New KBBF and RBBF deep ultraviolet (DUV) and vacuum ultraviolet (VUV) crystals are now
available that enable direct doubling of the SHG output of these tunable Ti: Sapphire lasers to directly
achieve wavelengths as short as 175 nm without the need to generate the 3rd harmonic and utilize frequency
mixing. This results in a highly efficient output in the DUV/VUV, enabling improved signal to noise ratios
(S/N) in these previously difficult wavelength regions. Photonics Industries has recently achieved a few
mW of power at 193nm with such direct doubling crystals.
The near and mid-IR spectral region is of significant interest due to the atmospheric windows
present in this region. Applications of lasers operating in this spectral region range from their use in remote
sensing LIDAR, IR counter measures (IRCM), spectroscopy and Chemical, Biological, Radiological,
Nuclear, and Explosives (CBRNE) sensing systems. We report the development of a compact, highly
efficient, high power intra-cavity pumped all-solid-state optical parametric oscillator (OPO) producing
nanosecond pulses at kHz repetition rates with an output tunable from 1.5 microns to 3.4 microns with
pulse energies up to 10mJ. With our novel Intra-Cavity OPO design, pump to signal conversion efficiencies
up to 65% (which is very close to its quantum efficiency) at room temperature are achievable.
Single Longitudinal Mode (SLM) lasers are of interest for various coherent LIDAR techniques
that utilize the Doppler wavelength shifting effect. Also, narrow linewidth lasers are of interest for
Differential Absorption LIDAR (DIAL) which can precisely identify trace chemical species. However,
such SLM lasers are often limited to low (~100Hz) rep rates due to laser seeding limitation. We report the
development of a seeded SLM technology that enables us to achieve up to 85W of power at 1064nm with a
linewidth less than 100 MHz. Furthermore, such SLM powers can be realized at rep rates up to 10 kHz
enabling a myriad of next generation of narrow linewidth laser applications. We have built both watercooled
and air-cooled versions of theses SLM lasers for various power level requirements.
The mid-infrared spectral region is of significant interest due to the atmospheric absorption lines present in this region.
We report the development of a compact, highly efficient, high power intra-cavity pumped all-solid-state optical
parametric oscillator (OPO) producing nanosecond pulses with an output tunable from 1.5 microns to 3.4 microns with
pulse energies ranging from 0.5mJ to over 4mJ over the entire range at kHz repetition rates. We have built both watercooled
and air-cooled versions of the OPO for various power level requirements.