We describe efficient operation in an intracavity-doubled, diode bar-pumped N d WO, laser using a newly designed stackedglass plate (SGP) beam shaper.' The pumping schema with the SGP shaper is shown in Fig. 1. We used 20-W diode bars as a pump source. It has 10 mm X 1 p m emitting dimensions with a divergence of 20" X 50" (full angle) for horizontal and vertical dimensions (M2 is about 2000 X diffraction limited). The SGP beam shaper consists of two sets of 15 SGPs. Each plate (25 mm square) is 1.5 mm thick and is stacked with a twist offset. The diode bar beam collimated in the vertical plane is condensed at the entrance of the first SGP and divided into 15 beams. Each beam is refracted at a different angle and transmitted in a different direction in a glass plate. As a result, each beam is emitted with a 1. 5. " gap in the vertical plane from the first SGP is exactly the same as the first one but positioned at a right angle to the first one. The second SGP causes all 15 beams from the SGP to be overlapped in the horizontal plane. As a result, M' of the diode bar beam is improved by a factor of about 15 in the horizontal dimension. Additionally, this beam shaper has a high transmission of 93% for the diode bar beam. The 15 stacked beams are then focused with a cylindrical and a spherical lens.The laser design is shown in Fig. 2. For simplicity and reduction of cavity loss, we performed HR coating directly on the 1% Nd: WO, (3 X 3 X 1 mm) laser mounted in a water cooler. The pump beam from the SGP shaper was focused to about 800 p m square in diameter in the Nd.YV0,. Noncritically phase-matched LBO crystal (type 1) held at 148OC was used for frequency doubling. We also developed a low-loss, high-durability (for heating) dual-band AR coating for the LBO crystal. 2pW LD-bar Beam shaper Cylindrical lens CThAl Fig. 1. Schematic of focusing arrangement with stacked-glass plate beam shaper.532nm tput CThAl Fig. 2. Laser design of intracavitydoubled Nd:WO, laser end pumped by diode bars. W c E $4 1 a * Y 8 E c hl m VI 10 20 30 40 Pump power (W) CThAl Fig. 3. Input-output data of intracavity-doubled Nd:YVO, laser. 7 W, TEMOO green light was obtained for 30 W pumping power.The laser, including the diode bars, has been assembled into a 140 X 126 X 450 (mm) laser head. An output power of 7 W in the TEMOO mode was achieved with 30-W pumping power as shown in Fig. 3. The measured M2 of green light was less than 1.2. To the best of our knowledge, this is the highest TEMOO mode efficiency in intracavity-doubled cw N d W O , laser pumped by nonfiber coupled diode bars. In addition, these results indicate the possibility of a greater than 10 W green laser if a two-end pumping design is applied because the output power (7 W) is not limited bythermal aberration ofNdWO, but onlybypumping power.Cerium-doped LiCaAlF, (Ce:LiCAF) and LiSrAlF, (Ce:LiSAF) have been shown to be efficient means of generating tunable Uv radiation when pumped by a fourth-harmonic of Nd:YAG lasers. High repetition rate oscillators,' high energy per pulse osci...

In widely tunable lasers such as Ti:Sapphire and Cr:LiSAF lasers, the tuning region is limited by the bandwidth of the mirror coatings rather than the potential tuning region of the laser material itself. To overcome these problems, we have been developing extremely broadband, lowloss mirrors which enable full range tuning of such tunable lasers. In this paper, we report the results for near infrared broadband mirrors which cover the entire tuning range of Ti:Sapphire and Cr:LiSAF lasers. These mirrors have reflectances of 99.85% to 99.95 % for wavelengths of 680 to 1060 nm.

Laser damage thresholds of fluoride HR coating were investigated at 352nrn, iOns pulses. Additionally, the effective method to reduce the crazing in fluoride HR coatings were studied.The high threshold greater than 30J/crn2 was achieved in LaF3/A1F3 coating when laser conditioning procedure was used. The lAD process or double stack design with combination of fluoride and Hf02/Si02 coating was effectable to reduce the crazing.

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