Evaluating the effect of transmissive optic thermal lensing on laser beam quality with a Shack–Hartmann wave-front sensor

Abstract

We examine wave-front distortion caused by high-power lasers on transmissive optics using a Shack-Hartmann wave-front sensor. The coupling coefficient for a thermally aberrated Gaussian beam to the TEM(00) mode of a cavity was determined as a function of magnitude of the thermally induced aberration. One wave of thermally induced phase aberration between the Gaussian intensity peak and the 1/e(2) radius of the intensity profile reduces the power-coupling coefficient to the TEM(00) mode of the cavity to 4.5% with no compensation. With optimal focus compensation the power coupling is increased to 79%. The theoretical shape of the thermally induced optical phase aberration is compared with measurements made in a neutral-density filter glass, Faraday glass, and lithium niobate. The agreement between the theoretical and the measured thermal aberration profiles is within the rms wave-front measurement sensitivity of the Shack-Hartmann wave-front sensor, which is a few nanometers.

Faraday Isolators for High Average Power Lasers

“…In (Mueller et al, 2002;Mansell et al, 2001) this value appeared to be twice as small as it should be because of mistake made in the calculations. For a super-Gaussian beam (29), all the formulas in Table 3 are valid if A i is replaced by А i (m), expressions for which are given in Table 2.…”

“…Hereinafter we shall call this method "telescopic compensation" and indicate corresponding losses by subscript "TC". In (Mansell et al, 2001;Mueller et al, 2002) an adaptive method (subscript "AC") for compensating the thermal lens was suggested and experimentally studied. A compensating glass was placed before polarizer 1 (dotted line in Fig.…”

“…As a result, heat release power is at least tenths of percent of transmitted laser power P 0 . (Zarubina & Petrovsky, 1992), 2 (Zarubina et al, 1997), 3 (Chen et al, 1998), 4 (Jiang et al, 1992), 5 (Kaminskii et al, 2005), 6 (Yasuhara et al, 2007), 7 (Raja et al, 1995), 8 (Barnes & Petway, 1992), 9 (Ivanov et al, 2009), 10 (Slack & Oliver, 1971), 11 (Chen et al, 1999), 12 (Wynands et al, 1992), 13 , 14 (Mueller et al, 2002), 15 (Mansell et al, 2001), 16 (Khazanov et al, 2002a), 17 (Mukhin et al, 2009), 18 (VIRGO-Collaboration, 2008), 19 (Malshakov et al, 1997), 20 (Andreev et al, 2000a), 21 (Zarubina, 2000), 22 (Davis & Bunch, 1984).…”

In-vacuum Faraday isolation remote tuning

“…This FI is operating in a 10 −6 mbar vacuum environment, and it has to accommodate a beam having a several millimeter diameter size and several Watts of power. Owing to the quite large light intensity in the FI crystal, thermally induced effects in the FI were expected and observed, as thermal lensing [5], with consequent beam/interferometer mismatching, and optical isolation degradation ( [6][7][8]). Reference [9] reports on the first observation of a further, formerly unexpected at this level, significant change of the optical isolation of an FI, which, having been tuned in air, once put in vacuum, experiences an isolation loss exceeding 10 dB.…”

Fabrication and performance optimization of the magneto-optical (Tb1−xRx)3Al5O12 (R = Y, Ce) transparent ceramics

“…1,2 A high Verdet constant, size scalability, a high laserinduced-damage threshold, and a high thermal conductivity are required for such material for high power laser applications. Terbium aluminum garnet (Tb 3 Al 5 O 12 (TAG)) single crystal is an excellent magneto-optical material with good transmittance in the 500-1500-nm region, 3,4 high thermal conductivity, and higher Verdet constant than the most commonly used terbium gallium garnet (Tb 3 Ga 5 O 12 (TGG)) single crystal.…”