Browsing by Author "Liang, Hsin-Chih"

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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.
Exploring the Emergence of the Self-Q-Switching in Diode-Pumped Yb:KGW Monolithic Lasers
(2018-09-01)
Huang, Tzu-Lin
;
Liang, Hsin-Chih
;
Su, Kuan-Wei
;
Chen, Yung-Fu
;
電子物理學系
We perform through experiments to explore the key factors for the emergence of a self-Q-switching phenomenon in diode-pumped Yb: KGW lasers. In addition to the output transmission, it is found that the mode-to-pump size ratio is a critical factor leading to the self-Q-switching. The region of the cavity mode volume without overlapping the pump volume plays a role of modulation loss to result in self-Q-switching. With an output transmission of 4% and a mode-to-pump size ratio of approximately 1.2, simultaneous self-Q-switching and self-mode-locking with the repetition rate of 23.1 GHz were experimentally observed. At an incident pump power of 9.2 W, the maximum pulse energy was estimated to be 1.4 mu J at the repetition rate of 880 kHz with an average output of 1.27 W.
Flexibly Controlling the Power Ratio of Dual-Wavelength SESAM-Based Mode-Locked Lasers With Wedged-Bonded Nd: YVO4/Nd: GdVO4 Crystals
(2018-09-01)
Liang, Hsin-Chih
;
Huang, Tzu-Lin
;
Chang, Feng-Lan
;
Sung, Cheng-Lin
;
Chen, Yung-Fu
A new diffusion-bonded Nd: YVO4/Nd: GdVO4 hetero-structure crystal with oblique interface between two vanadate materials is exploited to achieve dual-wavelength passively mode-locked laser with a semiconductor saturable absorber mirror. Experimental results show that the power ratio of the two emission wavelengths can be flexibly adjusted by controlling the vertical position of pump beam. In the optimally balanced dual-wavelength operation, the maximum total output power of 2.5 W is obtained at an incident pump power of 11 Wand the pulse width is measured to be 24.7 ps with pulse repetition rate of 296.6 MHz. The mode-locked output pulse is further found to exhibit an optically beating with pulse duration of 1.8 ps at a repetition rate of 0.318 THz.
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.
Orthogonally Polarized Self-Mode-Locked Lasers With Repetition Rate Multiplication up to Hundreds of Gigahertz: Observation of Temporal Carpets
(2018-09-01)
Chen, Yung-Fu
;
Chang, Ming-Ting
;
Huang, Tzu-Lin
;
Tung, Jung-Chen
;
Huang, Kai-Feng
Mode-locked laser sources with high repetition rates in the range of 10-1000 GHz are of considerable interest in modern communications, optical metrology, and photonic applications. Currently, developed laser systems generally suffer from the hardware complexity and energy loss. Here, we demonstrate a compact robust scheme based on a self-mode-locked monolithic Yb:KGW laser with external feedback coupling to achieve numerous repetition rate multiplications in the range of 25-330 GHz. The output pulse train consists of two orthogonally polarized components to form a vector state that is beneficial to practical applications. More intriguing, the pulse train measured as a function of the distance of the coupling feedback reveals a feature of the fractional recurrence that is like the Talbot carpet. An analytic formula is derived to manifest the formation of the temporal carpets. The developed experiment and formula not only pave a useful way for generating ultrahigh-repetition-rate femtosecond lasers but also provide new perspectives in the fractional recurrences of coherent waves.
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.