Damage properties of ZnGeP_2 at 2 μm

Peterson, Rita D.; Schepler, Kenneth L.; Brown, Jeff L.; Schunemann, Peter G.

doi:10.1364/josab.12.002142

Cited by 40 publications

(31 citation statements)

References 7 publications

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“…The LIDT using this more rigorous definition was significantly lower than the results of Peterson et al 6 The LIDT for ARcoated single crystal ZGP optical parametric oscillator (OPO) samples was found to be ~2 J/cm 2 for a 2.09 μm wavelength and 2 Hz repetition rates and ~1 J/cm 2 for a 2.05 μm wavelength and 10 kHz repetition rates. The higher frequency (10 kHz) repetition rates are much more typical of what the OPO would encounter during standard operation.…”

Section: Introductioncontrasting

confidence: 57%

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Increasing the laser-induced damage threshold of single-crystal ZnGeP_2

et al. 2006

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information AFRL-ML-WP-TP-2007-418 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY ACRONYM(S) AFRL-ML-WP Materials and Manufacturing Directorate Air Force Research Laboratory Air Force Materiel Command Wright-Patterson AFB, OH 45433-7750 SPONSORING/MONITORING AGENCY REPORT NUMBER(S) AFRL-ML-WP-TP-2007-418 DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited. SUPPLEMENTARY NOTESJournal article submitted to Journal of the Optical Society of America B. The U.S. Government is joint author of this work and has the right to use, modify, reproduce, release, perform, display, or disclose the work. PAO Case Number: AFRL/WS 06-0773, 22 Mar 2006. This paper contains color content. ABSTRACTThe laser induced damage threshold (LIDT) of single crystal zinc germanium phosphide (ZGP), ZnGeP 2 , was increased to 2 J/cm 2 at 2.05 μm and 10 kHz pulse rate frequency (double the previously measured value of 1 J/cm 2 ). This increased LIDT was achieved by improving the polishing of ZGP OPO crystals. The surface preparation of ZGP samples was determined to be of great importance because laserinduced damage has been observed to always initiate at the surface rather than in the bulk of the material. Two different polishing techniques were evaluated by comparing the surfaces of ZGP samples fabricated in the same manner apart from the polishing stage. Surfaces were characterized using scanning white light interferometry (SWLI) in order to determine RMS surface roughness and sample flatness. The photon backscatter technique (PBS) was used to determine the degree of surface and subsurface damage in the sample induced through the fabrication process. Both uncoated and anti-reflection coated samples were damage tested. The effect of subsurface damage in the samples was studied by removing different amounts of material during polishing for otherwise identical samples. The amount of material removed was correlated to the observed LIDT. Statistical LIDT was measured using a high-average-power, repetitively Q-switched Tm,Ho:YLF 2.05-μm pump laser. On average, lower surface roughness and photon backscatter measurements was a good indicator of ZGP samples exhibiting higher LIDT. The removal of more material during polishing significantly improved the LIDT of otherwise identical samples, indicating the importance of subsurface damage defects in the LIDT of ZGP. SUBJECT TERMSlaser induced damage threshold, mid-infrared materials, non-linear ...

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Section: Introductioncontrasting

confidence: 57%

“…A study by Peterson et al 6 during the early development of ZGP remains the only widelyavailable systematic study on the LIDT of this material to date. Because the study occurred early in the development of ZGP, the size and number of available samples was limited, resulting in a limited statistical sample size.…”

Section: Introductionmentioning

confidence: 99%

Increasing the laser-induced damage threshold of single-crystal ZnGeP_2

et al. 2006

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“…Previous studies have shown that laser-induced damage in ZGP single crystals always initiates at the surfaces rather than in the bulk of the material, making the surface preparation of ZGP samples of great importance [8][9][10]. Aside from surface preparation, Peterson et al [8] determined that damage in ZGP was governed by the energy density (J/cm 2 ) rather than the power density (MW/cm 2 ) for pulsewidths of a few nanoseconds or shorter. Because the laser damage mechanism in ZGP is dependent on the energy density, one method of increasing the amount of energy that can pass through a crystal without causing damage is to increase the pump spot size, making large aperture samples desirable for this purpose.…”

Section: Introductionmentioning

confidence: 99%

Large aperture single crystal ZnGeP2 for high-energy applications

Zawilski

Schunemann

Setzler

et al. 2008

Journal of Crystal Growth

102

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“…Plane mirrors were used throughout and the cavity was built with a fixed separation between M1 and M2 of 30 mm. The pump beam was focussed to a waist inside the OPO crystal and care was taken that the fluence at the crystal face did not exceed the damage threshold for the coated surface, ~2 J/cm 2 [1] . The crystal was mounted on a calibrated rotation stage that allowed the phase-matching angle to be optimised for each crystal to account for small variations in the cut-angle.…”

Section: Assessment Of Opo Performancementioning

confidence: 99%

“…Optical parametric oscillators (OPOs) based on zinc germanium phosphide (ZGP) offer a route to tuneable radiation in the mid-IR waveband exploiting powerful near-infrared lasers as pump sources. ZGP has a high non-linear coefficient (75 pm/V), high thermal conductivity (36 W/m/K) and a reasonable damage threshold [1] (~2 J/cm 2 at 2 µm). The intrinsic transparency range stretches from below 1 µ m to beyond 9 µ m, but in practice, growth defects [2] [3] result in loss in transmission for wavelengths shorter than ~2.5 µm.…”

Section: Introductionmentioning

confidence: 99%

Studies of optical loss in ZGP OPO devices for near- to mid-infrared conversion

Perrett

Harris

2004

SPIE Proceedings

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Zinc germanium phosphide (ZGP) is well suited to use in optical parametric oscillators (OPOs) for conversion of near-infrared laser output into the mid-infrared waveband (3 to 5 µm). Typical OPO applications seek to exploit pump wavelengths close to 2 µm so that both the output wavelengths fall within the mid-infrared waveband. However, the material typically suffers optical loss arising from growth defects that becomes significant at wavelengths below about 2.5 µm. We report the results of calorimetric studies that show that the loss can comprise both absorptive and scattering components. We have assessed the affect of loss at the pump wavelength on the conversion efficiency of a high pulse repetition frequency, doubly-resonant, ZGP OPO pumped with 2.094 µm radiation generated by a wavelength doubled Nd:YLF laser. The OPO used crystals having loss coefficients in the range 0.03 cm -1 to 0.3 cm -1 . The reduction in slope efficiency for the conversion process was evaluated over a range of pump beam diameters (1/e 2 intensity) from 0.12 mm to 0.30 mm. For the largest beam diameter a slope efficiency of 57 % was measured for a ZGP OPO crystal having a loss coefficient of 0.03 cm -1 . The slope efficiency reduced to about 30 % when the loss coefficient was increased to 0.3 cm -1 .

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Damage properties of ZnGeP_2 at 2 μm

Cited by 40 publications

References 7 publications

Increasing the laser-induced damage threshold of single-crystal ZnGeP_2

Increasing the laser-induced damage threshold of single-crystal ZnGeP_2

Large aperture single crystal ZnGeP2 for high-energy applications

Studies of optical loss in ZGP OPO devices for near- to mid-infrared conversion

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