This work presents a study of a fully nonastigmatic design of a single-longitudinal-mode, wavelength-tunable, unidirectional alexandrite ring laser cavity and assessment of its performance compared to more complex laser design requiring astigmatism compensation. A “displaced mode” nonastigmatic laser cavity design eliminating astigmatic cavity elements is developed around an alexandrite crystal end-pumped by a low-brightness, high-power red diode laser pump system. Single-longitudinal-mode, continuous-wave operation is demonstrated with output power of 700 mW with an excellent ${\rm{TEM}}_{00}$ mode (${{\rm{M}}^{2}} \lt {1.1}$) across a wide pump power range. Wavelength tuning from 748–773 nm is produced using a birefringent filter plate. The nonastigmatic alexandrite laser design achieves better spatial quality and resilience to maintain ${{\rm{TEM}}_{00}}$ operation across wide variation in pump-induced lensing compared to the astigmatic design. To the best of our knowledge, this is the first wavelength-tunable, single-longitudinal-mode operation of a unidirectional alexandrite ring system in a fully nonastigmatic cavity regime.

中文翻译：

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具有波长可调单纵模操作的非散光亚历山大变环形激光器设计

这项工作提出了对单纵向模式，波长可调，单向变石翠绿环形激光腔的完全非散光设计的研究，并与需要像散补偿的更复杂的激光设计相比，对其性能进行了评估。围绕着由低亮度，高功率红色二极管激光泵浦系统泵浦的翠绿宝石晶体开发了一种“位移模式”非散光激光腔设计，消除了像散腔元件。在出色的$ {\ rm {TEM}} _ {00} $模式（$ {{\ rm {M}} ^ {2}}的情况下，以700 mW的输出功率演示了单纵模连续波工作\ lt {1.1} $）在很宽的泵功率范围内。使用双折射滤光片可在748–773 nm范围内进行波长调谐。与散光设计相比，非散光变石翠绿激光器设计具有更好的空间质量和弹性，可以在泵激透镜的各种变化中维持$ {{\ rm {TEM}} _ {00}} $的运行。据我们所知，这是完全非散光腔态下单向亚历山大变石环系统的首次波长可调，单纵模操作。