>30 W vortex LG₀₁ or HG₁₀ laser using a mode transforming output coupler

Abstract

High-power vortex light generated directly from lasers will help drive their applications in material processing, optical manipulation, levitation, particle acceleration, and communications, but limited power has been achieved to date. In this work, we demonstrate record vortex average power of 31.3 W directly from a laser, to the best of our knowledge, using an interferometric mode transforming output coupler to convert a fundamental mode Nd:YVO4 laser into a LG01 vortex output. The vortex laser was Q-switched with up to 600 kHz pulse rate with a high slope efficiency of 62.5% and an excellent LG01 modal purity of 95.2%. We further demonstrate > 30W laser power in a high quality HG10 mode by simple adjustment of the output coupler. Experimental investigations of varying output coupling transmission are compared with theory. This successful implementation of the interferometric output coupler in a high power system demonstrates the suitability of the mode transforming method for robust turn-key vortex lasers with high efficiency and high modal purity, with scalable power and pulse rate.

Yb fiber vortex laser using an interferometric mode converting output coupler

“…Full details of this technique can be found in previous work. 9 To control the mode size and recoupling of the free-space mode, a 8 mm focal length aspheric lens imaged the fiber mode output to a 190 µm diameter waist at the mid-point of the VOC. When reflected back to the fiber via the VOC, this ensured the optimal conditions to re-couple the mode back into the fiber and complete the resonator.…”

“…Direct emission of vortex modes from lasers is an attractive proposition to make them more simple and compact, along with a potentially more robust system as a whole. This concept has had some application in fiber resonators, 7 and in this work we aim to apply the technique of interferometric mode conversion using a vortex output coupler 8,9 to a fiber oscillator. This technique allows direct extraction of a high purity vortex state, while the fiber oscillator can operate on its favoured fundamental Gaussian mode internally.…”

Recent Progress in Nonlinear Frequency Conversion of Optical Vortex Lasers

“…In Figure 2, we presented a summary concerning intracavity generation of vortex beams. Other unconventional approaches such as using volume Bragg grating and other diffractive elements have also been developed over these years [71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86]. Many reports have already performed a thorough review of the development of optical vortex lasers concerning its generation, tunability, and control of vortex handedness.…”

Controlled Generation of High‐Purity Scalar Orbital Angular Momentum States from a High‐Power Single‐Crystal Fiber Laser

“…[15,22] A modified Sagnac interferometer has been employed as an output coupler to improve power-scaling capability through the intracavity interference of Gaussian beams; however, it is typically limited to the lowest OAM state (l = ±1). [29] In fact, most current OAM laser sources produce low-order OAM states that are limited by the cavity design. [30,31] The generation of high-order states through artificial control of the exact amount of l remains challenging.…”