&lt;title&gt;Q-switched multikilowatt CO2 laser system excited by microwaves&lt;/title&gt;

Bielesch, Ulrich; Budde, Max; Fischbach, M.; Freisinger, Bernhard; Schaefer, Johannes Heinrich; Uhlenbusch, J.; Vioel, Wolfgang

doi:10.1117/12.144686

Cited by 15 publications

(6 citation statements)

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“…The mean saturation intensity calculated for the laser module was Īs = 458 W cm −2 for w = 30 cm and a CO 2 :N 2 :He = 4.5:13.5:82 mixture with a dissociation degree equal to 57% at p = 5.8 kPa. This agrees fairly well with the value of 550 W cm −2 determined for the saturation intensity based on measurements [11]. The magnitude of Īs agrees also with values of the saturation intensity calculated [3] or measured [5] for axial-flow CO 2 lasers operating under similar conditions as the laser described in [11,12].…”

Section: Resultssupporting

confidence: 90%

“…This agrees fairly well with the value of 550 W cm −2 determined for the saturation intensity based on measurements [11]. The magnitude of Īs agrees also with values of the saturation intensity calculated [3] or measured [5] for axial-flow CO 2 lasers operating under similar conditions as the laser described in [11,12].…”

Section: Resultssupporting

confidence: 90%

“…Such calculations were made for a multikilowatt CO 2 laser system [11] consisting of a line of axialflow microwave discharge modules [12].…”

Section: Resultsmentioning

confidence: 99%

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Calculation of the saturation intensity for fast-flow lasers

Stańco¹

1997

J. Phys. D: Appl. Phys.

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The behaviour of , the saturation intensity averaged over the optical cavity width w of a transverse-flow laser, is discussed based on a numerical analysis of a laser of that type. It is shown that for any w the mean saturation intensity is almost independent of the cavity position x along the flow and remains nearly unaffected by the optical power extraction upstream of the cavity. Thus, similarly as for non-flow lasers, it can be used, in conjunction with the small-signal gain coefficient averaged over the cavity width, for prediction of the optical power available from a transverse-flow laser and optimization of the optical cavity position and width. For axial-flow lasers the available optical power can be predicted in the same way if the beam path along the discharge is taken for w.

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 90%

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Calculation of the saturation intensity for fast-flow lasers

Stańco¹

1997

J. Phys. D: Appl. Phys.

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“…The experimental result ofthe cw amplification is shown in Fig.6 together with a calculation by using the Rigrod equation, 1nt) g0 . L -('outun ) (2) where 'out, Tm, I are output intensity, input intensity and saturation intensity in W/cm2, respectively. The fitted small signal gain g0 and saturation intensity I are 1 %/cm and 1600 W/cm2 , respectively.…”

Section: Concept Of the Laser Drivermentioning

confidence: 99%

Development of short pulse and high power CO 2 laser for EUV lithography

Endo¹,

Hoshino²,

Ariga³

et al. 2005

Laser-Generated, Synchrotron, and Other Laboratory X-Ray and EUV Sources, Optics, and Applications II

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Laser produced plasma EUV source is the candidate for high quality, 1 15 W EUV light source for the next generation lithography. Cost effective laser driver is the key requirement for the realization of the concept as a viable scheme. A CO2 laser driven LPP system with a Xenon droplet target is therefore a promising light source alternative for EUV. We are developing a high power and high repetition rate CO2 laser system to achieve 10 W intermediate focus EUV power. High conversion efficiency (CE) from the laser energy to EUV in-band energy is the primarily important issue for the concept to be realized. Numerical simulation analysis of a Xenon plasma target shows that a short laser pulse less than 15 ns is necessary to obtain a high CE by a CO2 laser. This paper describes on the development of a CO2 laser system with a short pulse length less than 15 ns, an average power of a few kW, and a repetition rate of 100 kHz based on RFexcited, axial flow CO2 laser modules. Various issues are reported on the laser system design, namely 100W seeder, parasitic oscillation suppression, small signal gain and saturation fluence, and beam quality. Additional approach to increase the amplification efficiency is discussed. Acknowledgement: This work was supported by NEDO.

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“…CO 2 Transverse-Electric-Atmospheric (TEA) lasers produce necessary energy in a short pulse format, but their drawback is the limited repetition rate, and hence average power. Attempts were reported a decade ago to operate microwave excited CO 2 laser modules in a Q-switched oscillator mode and an oscillator-amplifier mode 8,9 . Typical performances at repetition rate of 4 kHz with output average power of 680 W and 10 kHz with average power of 800W were pulse energy of 170 mJ, pulse width in full width half maximum (FWHM) of 250 ns, and 70 mJ, 35 ns, respectively.…”

Section: Introductionmentioning

confidence: 99%

Efficient and compact short pulse MOPA system for laser-produced-plasma extreme-UV sources employing RF-discharge slab-waveguide CO 2 amplifiers

Nowak¹,

Suganuma²,

Endo³

et al. 2008

High-Power Laser Ablation VII

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Recent studies of fundamental issues of target material format and laser radiation parameters 1,2 have revealed the attractiveness of LPP EUV source technology based on Sn target and multi-kW CO 2 laser driver. In recent work 3 we have reported 8kW of average power at 100kHz repetition frequency and 20ns pulse duration produced by our MOPA CO 2 laser driver built on a chain of Fast Axial Flow (FAF) amplifiers. However, the oscillator power is insufficient to saturate the input stages and significant amount of available laser energy (>80%) is untapped. In this paper we report a step towards an improvement of laser driver power and efficiency. For the first time, to our knowledge, the performance of a novel multi-pass pre-amplifier based on RF-excited slab waveguide CO 2 laser technology has been numerically modeled. The calculations show the feasibility of this approach. We carried out amplification experiments to validate the numerical model. In our experiments we have obtained power gain of 10 at 13-pass configuration from a slab of 60x600mm2 geometry at 20ns pulse length and 100kHz repetition frequency at diffraction-limited output and no selfoscillation. The experiment has validated the numerical model, which will be used at this stage to design and optimize a pre-amplifier for our current FAF amplifier chain. Furthermore, these results enable us to design and optimize next generation of LPP laser driver based entirely on compact slab-waveguide amplifiers. *k.m.nowak@euva.or.jp; phone +81-463-35-9392; fax +81-463-35-9352; http://www.euva.or.jp

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<title>Q-switched multikilowatt CO2 laser system excited by microwaves</title>

Cited by 15 publications

References 0 publications

Calculation of the saturation intensity for fast-flow lasers

Calculation of the saturation intensity for fast-flow lasers

Development of short pulse and high power CO 2 laser for EUV lithography

Efficient and compact short pulse MOPA system for laser-produced-plasma extreme-UV sources employing RF-discharge slab-waveguide CO 2 amplifiers

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