In the assembly of optical resonators of optically pumped semiconductor lasers (OPSL), the highly reflective resonator mirror is the most crucial component. In previous cooperation, Coherent and Fraunhofer IPT have developed a robust active alignment strategy to optimize the output power of the OPSL resonator using search strategies for finding the laser threshold as well as hill-climbing algorithms for maximizing the output power. Beam-shape as well as the laser mode have major influence on the quality and the duration of subsequent beam-shaping and fiber-coupling steps. Therefore, the alignment algorithm optimizing the output power has been extended recently by simultaneous image processing for ensuring a Gaussian beam as the result of alignment. The paper describes the enhanced approach of automated alignment by additionally scanning along the optical resonator and subsequently evaluating and optimizing the roundness of the beam as well as minimizing the beam radius through twisting and tilting of the mirror. A quality metric combining these measures is defined substituting an M² measurement. The paper also describes the approach for automated assembly including the measuring setup, micromanipulation and dispensing devices.
We achieved 100mW cw of 593nm by intracavity sum frequency generation in a branched cavity, dual laser set up. Two
gain media were used: Nd:YVO4 for generating 1342nm, diode-pumped by 3.7W at 808nm, and an optically pumped
semiconductor chip (OPS), designed for 1064nm emission, diode-pumped by 1.7W at 808nm. Due to the short
upperstate lifetime of the OPS, the generated 593nm output power was stable.A
For high precision beam steering usually complex and sophisticated mechanics are necessary to keep the alignment long term stable. Here we present a simple temperature controlled steering device based on a crystal with different temperature expansion coefficients in its axes. Results for single mode fiber coupling of visible lasers will be presented.
Optically Pumped Semiconductor Lasers - OPSLs - have been introduced in 2001. Their unique features
such as power scalability and wavelength flexibility, their excellent beam parameters, power stability and
reliability opened this pioneering technology access to a wide range of applications such as flow cytometry,
confocal microscopy, sequencing, medical diagnosis and therapy, semiconductor inspection, graphic arts,
forensic, metrology.
This talk will introduce the OPSL principles and compare them with ion, diode and standard solid state lasers.
It will revue the first 10 years of this exciting technology, its current state and trends. In particular currently
accessible wavelengths and power ranges, frequency doubling, ultra-narrow linewidth possibilities will be
discussed. A survey of key applications will be given.
High power compact UV lasers with diffraction limited beam are required for industrial applications such as laser direct
imaging, wafer inspection or photo voltaic. By use of a Nd:YVO4 oscillator with a Saturable Bragg Reflector and a
single pass amplifier, 73 W output power in mode-locked operation at 80 MHz have been generated with high peak
power. By use of two LBO crystals a third harmonic output power of 35 W at 355 nm was demonstrated with an M2
value of <1.2. This corresponds to 48% nonlinear conversion efficiency.
Optically pumped semiconductor lasers are scalable up to several 10ths of Watts of output power, maintaining
excellent beam quality and high reliability. A further key advantage of the OPS technology is wavelength flexibility:
the accessible wavelength range spans from 915 nm to 1180 nm. Frequency doubling expands this into the blue to
yellow spectral range. The current investigation aims at applications (such as Raman spectroscopy) where ultra-narrow
bandwidth lasers are required. Results of a single frequency green-yellow OPS laser will be presented.
We present an air-cooled optically pumped semiconductor laser that provides a cw output power of 1W at 488
nm. This performance was achieved via intracavity frequency doubling at a laser diode pump power of 2.5
Watts. The increased efficiency was realized by optimizing the OPS chip design and improving the heat
extraction from the OPS chip. Efficient cooling of the OPS chip and a compact and mechanically stable folded
resonator provide maintenance-free long life laser operation with an M2 of less than 1.1 and a noise of less than
0.25% rms. The size of the laser head is the same as for the 20 mW commercially available version, namely
125 x 70 x 34 mm.
The lack of blue pump sources for Pr-doped materials has been overcome with the recent progress in optically
pumped semiconductor lasers (OPS) operating at 479 nm. The availability of reliable high power OPS pump lasers,
makes Pr3+-doped crystals ideal gain media for compact and efficient ultraviolet solid-state lasers with output power
in the Watt range.
We report on the scalability of a 522/261 nm Pr:YLF cw laser that is dual-end-pumped by two OPS lasers at 479 nm.
At 9.6 W of incident pump power more than 4 W were obtained at 522 nm with a slope efficiency of 45%.
Intracavity frequency doubling of 522 nm resulted in 1 Watt of cw UV output at 261 nm.
Diode pumped frequency doubled Optically Pumped Semiconductor lasers (OPS), has proven to be a reliable source
of laser radiation in the blue and blue-green spectral range between 460 nm and 505 nm. One of the major
advantages of using semiconductors as gain medium is the possibility to tailor the wavelength of the semiconductor
material by means of band gap engineering. Here we report about new OPS material enabling the wavelength region
between 1090 nm and 1160 nm which allows the realization of frequency doubled lasers between 545 nm and 580
nm. Laser results up to several Watts in the yellow spectral range as well as efficiency and lifetime data will be
presented.
In this paper, we report on 500 mW of cw ultraviolet radiation at 360 nm, which has been obtained by intracavity
frequency doubling of a Pr:YLF laser, end pumped by 1.8 W Coherent High Power OPS Laser at 479 nm. We have
demonstrated the scalability of Pr:YLF laser to pump power of 5.3Watts, resulting in real continuous wave 2.5 Watts
of output power at 720 nm and cw 1.3 Watts at 360 nm.
Compact DPSS UV sources are of interest for replacing Ar-Ion lasers in applications that require cw or quasi-cw laser
radiation. One way to generate UV light at 355nm and 266nm is by modelocking an IR Nd:YVO4 laser and converting
the ps pulses into the second, third, and fourth harmonic. The mechanism of choice is passive modelocking using a
Saturable Bragg Reflector (SBR). We have developed an air-cooled system capable of UV output powers in excess of
6W. Laser performance as well as lifetime data will be presented for wavelengths at 355nm and 266nm.
In this paper, we report on 2.5 Watts of output power at 522 nm of Pr:YLF laser end pumped by 5.3 W Coherent
High Power OPS Laser at 479 nm, and on 620 mW of cw ultraviolet radiation at 261 nm, which has been obtained
by intracavity frequency doubling of the Pr:YLF laser with a BBO crystal.
Lasers based on optically pumped semiconductors (OPS) offer unique capabilities in both wavelength tailoring and power scaling compared to traditional solid-state lasers. In particular, these lasers can be designed in wavelength to realize for instance 505nm, which enables excitation of two fluorescent dye chemistry sets originally established by 488 and 514 nm legacy argon lasers. Highly efficient intra cavity frequency doubling of an 1010nm OPS yields over 100 mW of output power at 505 nm. In this paper we will present a brief background on OPS technology. We will then discuss specifics of the 505 nm laser and present both performance and reliability data for this laser.
Optically pumped semiconductor material is a complimentary gain medium for rare earth or transition metal doped crystals. The design of several compositions based on GaAs allows the realization of a wavelength range between 710nm and 1180nm. This can be diode pumped and frequency doubled to cover the near UV up to the yellow spectral range. The power is scaleable and we have realized several Watts at 488nm and 460nm. Experimental results will be presented and discussed as well as reliability data to show that this technology has ripened for industrial applications.
A design concept suitable for space applications is proposed on the basis of a diode-pumped Nd:YAG laser transmitter laboratory breadboard; this transmitter must not only furnish the data carrier but also serve as a tracking reference and (in conjunction with a boost amplifier) as a beacon for receiver-station acquisition. The diffraction-limited beam is generated with 6.3-percent electrical-to-optical conversion efficiency. The proposed space communications system will incorporate astigmatically-focused stacked-laser diodes for continuous reliable operation over the course of seven years.
A transmitter laser breadboard suitable for a coherent space communication system is under development. Major design goals are 1W CW output power, 100 kHz linewidth at low drift, 8 percent electrical to optical conversion efficiency, and 3 dB power degradation over 7 years operation. An oscillation output of 600 mW is amplified by two double-pass stages to 1 W.
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