Date of Award
12-2016
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Legacy Department
Electrical Engineering
Committee Member
Dr. Eric G. Johnson, Committee Chair
Committee Member
Dr. John Ballato
Committee Member
Dr. Liang Dong
Committee Member
Dr. Joe Watkins
Committee Member
Dr. Lin Zhu
Abstract
In this work, the amplification of higher order modes, mainly focused on optical vortices that carry orbital angular momentum (OAM), were demonstrated and discussed in a Ho:YAG rod amplifier and Ho:YAG single crystal fiber (SCF) amplifier at 2 μm. Both experiments and simulations were carried out to understand the propagation, amplification and phase preservation of optical vortices in solid state amplifiers. A 3-D propagation model combining semi-vectorial BPM and steady state rate equations was used to verify the experimental results and to simulate the high power amplification. The amplification of optical vortices was experimentally demonstrated in a Ho:YAG rod amplifier for both – the case of incoherently multiplexed seeds and the case of coherently multiplexed seeds. A matched filter was used to evaluate the phase of the amplified seed beams and it is proven that the important phase information of the seeds was preserved through the amplification process. Pump beam profile engineering is also discussed for optimizing the gain for a desired seed beam. The amplification of optical vortices were also demonstrated in a Ho:YAG SCF amplifier. The SCF has a small diameter and a large surface-to-volume ratio to ensure guidance for both pump and seed beams. The optical spectroscopic properties, small signal gain and lasing characteristics of the Ho:YAG SCF were investigated. Then the amplification of higher order vortices was demonstrated in the SCF as well. The high power operation potential of the SCF amplifier is also discussed together with the associated thermal issues. With improved SCF fabrication techniques, SCF exhibits great potential to function as a high power multimode amplifier.
Recommended Citation
Li, Yuan, "Study on the Amplification of Spatial Modes in a Crystal Rod Amplifier" (2016). All Dissertations. 1834.
https://open.clemson.edu/all_dissertations/1834