Browsing by Author "Tuan, Pi-Hui"

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Compact High-Peak-Power End-Pumped AlGaInAs Eye-Safe Laser With a Heat-Spreader Diamond Coated as a Cavity Mirror
(2015-01-01)
Wen, Chi-Ping
;
Tuan, Pi-Hui
;
Liang, Hsin-Chih
;
Huang, Kai-Feng
;
Chen, Yung-Fu
We report on a high-peak-power end-pumped AlGaInAs laser at 1.52 mu m with a linear plane-parallel cavity. A high-reflective coated diamond is utilized not only as the heat spreader but also as the front mirror simultaneously to make the laser cavity to be extremely compact. The average output power and the corresponding peak power under this cavity configuration is found to be up to 2.58 and 516 W separately at a repetition rate of 100 kHz and a pump power of 12 W corresponding to a peak power of 2.4 kW. The experimental results assure the promising application of dielectric coated diamond as a multifunctional optics to fulfill a high performance and compact cavity design.
Generating High-Order Transverse Patterns in Optically Pumped Semiconductor Lasers
(2019-11-01)
Tuan, Pi-Hui
;
Hsieh, Yen-Hui
;
Tu, Chin-Wei
;
Lee, Chi-Chun
;
Tsou, Chia-Han
High-order pattern formation in an optically pumped semiconductor laser (OPSL) under a selective pumping with varying spatial overlap between the pump beam and transverse modes is explored. In contrast to transverse pattern generation by off-axis pumped solid-state lasers where the mode order can be flexibly increased, experimental results reveal that the selective pumping fails to realize high-order mode operation in OPSLs when the pump-to-mode size ratio and pump power are insufficiently large. On the other hand, several high-order patterns belonging to the Hermite-Laguerre-Gaussian (HLG) modes are observed when scanning a large-ratio pump beam to specific positions on the gain chip. These HLG modes are experimentally confirmed to mainly originate from the transverse non-uniformity of present OPSL chip, while their structural features cannot be simply correlated with the pump scanning positions. Nevertheless, it is believed that the first-time observation of pure HLG modes under the large-ratio pumping can offer useful insights into the high-order pattern manipulation in OPSLs.
Generation of High-Energy Geometric Structured Beams by Off-Axis Pumped Nd:YAG/Cr4+:YAG Lasers with Degenerate Resonators
(2018-01-01)
Tuan, Pi-Hui
;
Hsieh, Yen-Hui
;
Liang, Hsin-Chih
;
Su, Kuan-Wei
;
Chen, Yung-Fu
Off-axis pumped Nd:YAG/Cr4+:YAG lasers under degenerate cavity conditions are explored to achieve high-pulse-energy geometric modes for beam transformation. The employment of Nd:YAG crystal promises efficient passively Q-switched (PQS) operation with a flexible cavity length to ensure various PQS geometric modes with stable structures can be generated. It is experimentally confirmed that the output energy and peak power of the PQS geometric modes can easily reach up to over 100 mu J and 10 kW with fairly stable pulse trains in pure linear polarization. Various high-energy vortex beams carrying large angular momentum and diverse phase structures are achieved by converting the planar geometric modes into the circular ones to offer promising light sources for potential applications.
Generation of Higher Order Vortex Beams From a YVO4/Nd:YVO4 Self-Raman Laser via Off-Axis Pumping With Mode Converter
(2015-01-01)
Lee, Cheng-Yeh
;
Chang, Chuan-Ching
;
Cho, Chun-Yu
;
Tuan, Pi-Hui
;
Chen, Yung-Fu
The generation of high-order Hermite-Gaussian (HG) beams at the Stokes wavelength in a YVO4/Nd:YVO4 self-Raman laser with off-axis pumping is demonstrated. The high-order vortex beams at the Stokes field are successfully created by transforming these HG modes via an extra-cavity mode converter. The stimulated Raman scattering (SRS) threshold pump power for the diode-end-pumped laser is theoretically analyzed to verify the feasibility of generating high-order HG modes by off-axis pumping. At a pump power of 18.6 W, the SRS output powers can be higher than 1.0 W for the HG modes from TEM0,0 to TEM3,0. Under the same pump power, the maximum order can be up to TEM28,0.
Investigation on Polarization Features of Broad-Area Square-Shaped VCSELs with Different Frequency Detuning: High-Order Modes Assisted in Stable Polarization Emission
(2013)
Yu, Yan-Ting
;
Tuan, Pi-Hui
;
Su, Kuan-Wei
;
Chen, Yung-Fu
;
電子物理學系
We experimentally confirm frequency detuning is the crucial factor for being capable of polarization switching in broad-area square-shaped VCSELs. Intriguingly, the VCSEL can exhibit stable polarization in light output for relatively large frequency detuning.
Realizing High-Pulse-Energy Large-Angular-Momentum Beams by Astigmatic Transformation of Geometric Modes in an Nd:YAG/Cr4+:YAG Laser
(2018-09-01)
Tuan, Pi-Hui
;
Liang, Hsin-Chih
;
Huang, Kai-Feng
;
Chen, Yung-Fu
;
電子物理學系
An off-axis pumped Nd:YAG/Cr4+:YAG laser under different degenerate cavity conditions has been thoroughly studied to generate high-pulse-energy geometric modes for further beam transformation. Because of the employment of Nd:YAG gain crystal provides a flexible choice of cavity length to achieve efficient passively Q-switched (PQS) operation, various PQS geometric modes with stable spatial structures are generated. Moreover, it is experimentally confirmed that the output energy and peak power of the PQS geometric modes can easily reach up to over 100 mu J and 10 kW with fairly stable pulse trains in pure linear polarization. By using an astigmatic mode converter (AMC) to transform the planar geometric modes into the circular geometric modes, various high-energy vortex beams with large angular momentum and diverse phase structures are successfully realized to offer a promising light source for further application. The propagation evolution of the transformed geometric modes through the AMC was also analyzed theoretically to offer useful insights for the formation of the geometric vortex beams.
The Influences of Boundary Shapes on Polarization Characteristics and Lasing Modes in Broad-Area Vertical-Cavity Surface-Emitting Lasers With Cryogenic Detuning: Regular Versus Chaotic Cavities
(2015-11-01)
Yu, Yan-Ting
;
Tuan, Pi-Hui
;
Chiang, Po-Yi
;
Su, Kuan-Wei
;
Huang, Kai-Feng
The broad-area rectangular-shaped and stadiumshaped VCSELs with nearly the same aspect ratio are designed to explore the influence of lateral boundary shapes on polarization states and lasing spectra with large detuning by cryogenic cooling. For the rectangular-shaped VCSEL, the lasing modes usually exhibit linearly polarized state and their far-field emissions mainly concentrate on four diagonal directions. On the other hand, the lasing modes of the stadium-shaped VCSEL generally display two orthogonally polarized states and their far-field emissions extensively spread on azimuthal directions. More intriguingly, the lasing spectra of the two devices clearly manifest the features of the energy-level distribution in regular and chaotic quantum billiards, respectively.