Modern Laser Technology and Applications

Fabrication and Development of High-Power Diode-End-Pumped Nd-Doped Crystal Laser [ 下載 PDF ]

Yu-Jen Huang

High-power diode-end-pumped solid-state laser plays an important role in a variety of fundamental scientific and industrial fields. In this report, we introduce several methods for power scaling in diode-end-pumped Nd-doped crystal laser system, and the pros and the cons for each approach are comprehensively analyzed, particularly for the issue of improving beam quality. Among which, we have originally designed a Nd:YVO₄ crystal with multiple doping concentration to realize a high-power diode-end-pumped continuous-wave laser at 1064 nm with the output power of nearly 100 W, where the beam quality is better than 2. We also discuss the potential application and prospect for such light source.

High-Power and High Repetition Rate Pulsed Photonic Crystal Fiber Laser [ 下載 PDF ]

Wei-Zhe Zhuang, Kuan-Wei Su

We used the photonic crystal fi ber (PCF) as the gain medium to investigate the performances of the pulsed PCF lasers by various schemes such as (1) actively Q-switched PCF laser, (2) passively Q-switched (PQS) PCF laser, and (3) PCF amplifier. We can attain pulsed laser source with pulse energy of 0.51 mJ and pulse duration of 18.3 ns at the pulse repetition rate (PRR) of 10 kHz by means of active Q-switching. Employing an AlGaInAs multi-quantumwell semiconductor materials the saturable absorber to form a passively Q-switched scheme, we can obtain pulsed PCF laser with pulse energy of 1.1 mJ and pulse duration of 10 ns at the PRR of 6.5 kHz. To further shorten the output pulse duration, we use the PQS Nd:YVO₄/Cr⁴⁺:YAG laser as the seed to amplify. At the PRR of 14.9 kHz, output pulses with pulse duration of 2.2 ns and pulse energy of 0.22 mJ were achieved. In the nearly future, we will use the beam combining method to further scale up the pulse energy and output power of the pulsed PCF lasers.

Formation and Applications of Structured Light Beams Possessing Optical Vortices [ 下載 PDF ]

Yu-Chieh Lin, Cheng-Yeh Lee, Ting-Hua Lu

Generation of optical vortices associated with structured light beams plays an important role in practical applications. In this article, we theoretically confirm that a high-order 'flower-like' Laguerre-Gaussian (LG) mode can be transformed into a set of collinear crisscrossed Hermite-Gaussian (HG) modes embedded with twodimensional (2D) optical vortex array that defines an orbital angular momentum (OAM) state. Exploiting this conversion relation, we experimentally produce the OAM state of considerable two-dimensional (2D) optical vortex array by utilizing a rotatable π/2 cylindrical lens mode converter (π/2-CLMC). Moreover, we theoretically verify that converting the Hermite-Gaussian modes into the Laguerre-Gaussian can lead to the spatial morphologies of the two-dimensional (2D) coherent states to be transformed from Lissajous figures to trochoidal curves. With this transformational relationship, we experimentally generate various structured lights by exploiting a cylindrical-lens mode converter to transform the optical Lissajous modes. The present investigation not only manifests a notable method to generate optical coherent waves with various orbital spatial morphologies, but might provide some useful insight in the study of the vortex light beam and its further applications.

Explorations of a Q-Switched Laser Induced Water Jet on a Flat Free Water Surface and the Morphological Variations in the Temporal Evolution of the Water Jet [ 下載 PDF ]

Ross C. C. Chen, Yan-Ting Yu, Kuan-Wei Su

The dynamics of a water jet on a flat free surface are investigated using a nanosecond pulsed laser for creating an oscillating bubble with different depths beneath the free surface. The water jet shows a thin jet followed by a markedly thicker jet and a circular crown-like jet perfectly connected on the shoulder of the thick jet transited to the thin jet. The crown-like jet is generated from the collapse of a circular ring-shaped crater. In the temporal evolution of the water jet, we fi nd an intriguing pattern formation that the crown-like jet gradually closes and finally forms an air bubble. For certain depth, the air bubble perfectly encloses a water drop through the process of Plateau-Rayleigh instability.

Analogously Investigations in Characteristics of Two-Dimensional Quantum Billiards by Using Broad-Area Vertical Cavity Surface Emitting Lasers [ 下載 PDF ]

Yan-Ting Yu, Pi-Hui Tuan, Kuan-Wei Su, Kai-Feng Huang

We experimentally confi rmed that broad-area vertical cavity surface emitting lasers (VCSELs) can be utilized to analogously investigate characteristics of two-dimensional (2D) quantum billiards. We discovered that the near-field and far-field transverse patterns of a broad-area VCSEL evidently represent the coordinate-space and momentumspace wave functions of a 2D quantum billiard, respectively. For the optical spectrum of broad-area VCSELs, the high-resolution measurement clearly demonstrates that over a thousand cavity modes with a narrow linewidth can be perfectly exhibited in the subthreshold spontaneous emission spectrum. It is found that these subthreshold spontaneous emission spectra can manifest the signature of photon periodic orbits of the aperture shape, which is quite similar to the behaviors of the energy spectra of the 2D quantum billiards. Accordingly, it is concluded that the subthreshold emission spectra of VCSELs can be analogously used to manifest the quantum-billiard energy spectra.

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Industrial Applications and Development Prospect of Atomic Layer Deposition [ 下載 PDF ]

Chi-Chung Kei, Wen-Hao Cho, Chien-Pao Lin, Bo-Heng Liu, Chien-Hung Chen

Since the invention in 1960s, atomic layer deposition (ALD) has been attracted great attention. The miniaturization of semiconductor devices is another trigger of equipment development and commercialization of ALD by the end of last century. ALD is also considered as an enabling technique to replace conventional coating tool due to the requirements of coating conformity and thickness control in next generation devices. Therefore, ALD technique and equipment will play greater role in the semiconductor industry. On the contrary, ALD shows potential in nonsemiconductor industries, such as energy, optoelectronics and catalysis. Innovative ALD systems, such as plasmaenhanced ALD、batch ALD、spatial ALD、roll-to-roll ALD, powder ALD, were developed by the equipment suppliers on the basis of the industrial needs. The throughputs of ALD systems can match the requirement for industrial commercialization.

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Research and Development of a Portable Device for Intravenous Infusion [ 下載 PDF ]

Feng-Chyi Duh, Kuei-Hsin Hsu

Intravenous infusion (IV) is the continuous giving of liquid substances directly into a vein. Intravenous infusion may be used to correct electrolyte imbalances, to deliver medications, for blood transfusion or as fluid replacement to correct, for example, dehydration. Compared with other routes of administration, the intravenous route is one of the fastest ways to deliver fluids and medications throughout the body. But there are many disadvantages and risks to intravenous infusion. Taking this into consideration, this project is to research and development a portable device for IV infusion, this new design IV infusion device consists of a peristaltic pump that allows the fluid to flow one drop at a time and also reducing air bubbles; a controller with a digital screen, making it easy to see the flow rate; a container to arrange to the access device. This new design portable device for IV infusion allows precise control over the flow rate and total amount delivered of liquid substance.