Optimization of nonlinear coupling and use of aggressive Q-switch clipping on the pulse falling edge has enabled high
beam quality, internally frequency-converted, Nd:YAG lasers with output powers greater than 35 W at both green and
ultraviolet wavelengths. By retaining more energy in the rod after the pulse, such lasers operate with enhanced gain
levels and achieve greater nonlinear conversion. Operation in this gain-enhancement regime has enabled lasers with
highly variable pulse-widths. We demonstrate here that gain-enhanced laser operation with variable pulse energy and/or
delay between pulses is also possible. This combination of features and flexibility available in gain-enhanced,
frequency-converted lasers allows optimization of laser processing for a wide range of candidate materials.
We demonstrate a variable pulse width, internally-frequency-converted, near-diffraction-limited Nd:YAG laser with output power up to 40 Watts at 532 nm and pulse widths electronically adjustable over a 40-300 ns range. The variable pulse width is achieved by clipping the pulse decaying edge with the Q-switch in a laser cavity optimized for post-pulse gain insensitivity. This approach makes possible frequency converted lasers with pulse width and output power substantially independent of repetition rate.
We describe a passively mode-locked, diode-pumped Nd:YAG laser that is used for frequency-conversion applications. The laser is based on a Direct-coupled Pump gain element and saturable Bragg reflector. The laser produces a 20-ps pulse with a 100-MHz repetition rate in a compact commercial package. It has typically <0.2% amplitude noise and diffraction-limited output beam. The average power is typically 7-8 W, and peak power is 4 kW which makes it well-suited for efficient frequency conversion. Using 2 stages of LBO for cascaded second-harmonic and sum-frequency generation, we have obtained >1 W at 355 nm. In addition, we have generated super-continuum output in the visible and infrared from micro-structured nonlinear fiber with pumping both at 1064 nm and 532 nm. Current applications for this laser, primarily in the ultraviolet, include flow cytometry, stereolithography, and semiconductor inspection.
Lightsources employing quasiphasematched (QPM) nonlinear materials have demonstrated unique attributes for chemical sensing in the near- to mid-infrare spectral range (1 - 5 micrometers ). The advent of patterned-growth GaAs allows the first practical extension of QPM materials to operation in the long-wave IR (5 - 12 micrometers ). That wavelength range is particularly attractive for chemical sensing because it contains an atmospheric window, many molecular groups absorb there at distinct frequencies, and their absorptions tend to be strong relative to those in the near- and mid-IR. Here, the application of orientation-patterned GaAs (OPGaAs) for use in a continuous wave (cw) difference frequency spectrometer is described. The outputs of two external- cavity diode lasers operating in the 1.3 and 1.5 micrometers telecom bands are mixed in a OPGaAs crystal, producing tunable radiation at wavelengths near 8 micrometers . The application of the source to the measurement of a water vapor rovibrational absorption line is presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.