Compensation of thermally induced modal distortions in Faraday isolators
Compensation of thermally induced modal distortions in Faraday isolators
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DOI：
10.1109/jqe.2004.834766
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发表时间：
2004-09
影响因子：
2.5
通讯作者：
Efim Khazanov;N. F. Andreev;A. Mal'shakov;O. Palashov;A. Poteomkin;Alexander Sergeev;A. Shaykin;V. Zelenogorsky;I. A. Ivanov;Rupal Amin;G. Mueller;D. B. Tanner;D. Reitze
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文献类型：
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作者：
Efim Khazanov;N. F. Andreev;A. Mal'shakov;O. Palashov;A. Poteomkin;Alexander Sergeev;A. Shaykin;V. Zelenogorsky;I. A. Ivanov;Rupal Amin;G. Mueller;D. B. Tanner;D. Reitze
本文详细研究了大功率铽镓石榴石（TGG）法拉第隔离器热透镜效应的两种补偿方法：用普通负透镜补偿和用具有负dn/dT的FK 51肖特玻璃补偿。测量了TGG晶体和FK 51玻璃的关键热光常数。我们发现，无论是TGG还是FK 51，光弹效应对总热透镜的贡献都不能忽略。我们定义了补偿玻璃的品质因数，并表明对于FK 51，具有最佳焦点的普通负透镜更有效，但需要针对不同激光功率重新定位透镜。相比之下，使用FK 51作为补偿元件是无源的，可以在任何激光功率下工作，但不如简单的望远镜补偿有效。采用品质因数大于50的补偿玻璃、具有自然双折射的晶体或凝胶，可以大大提高自适应补偿的效率。
Two methods of compensation of thermal lensing in high-power terbium gallium garnet (TGG) Faraday isolators have been investigated in detail: compensation by means of an ordinary negative lens and compensation using FK51 Schott glass possessing a negative dn/dT. Key thermooptic constants for TGG crystals and FK51 glass were measured. We find that the contribution of the photoelastic effect to the total thermal lens cannot be neglected for either TGG or FK51. We define a figure of merit for compensating glass and show that for FK51, an ordinary negative lens with an optimal focus is more efficient, but requires physical repositioning of the lens for different laser powers. In contrast, the use of FK51 as a compensating element is passive and works at any laser power, but is less effective than simple telescopic compensation. The efficiency of adaptive compensation can be considerably enhanced by using a compensating glass with figure of merit more than 50, a crystal with natural birefringence or gel.