Browsing by Author "Lan, YP"

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A novel tunable diode laser with liquid crystal intracavity tuning element
(2004)
Pan, RP
;
Lan, YP
;
Chen, CY
;
Pan, CL
;
電子物理學系
We propose a novel and simple approach for tuning of the laser wavelength. A homogeneously aligned nematic liquid crystal (NLC) cell with 4'-n-pentyl-4-cyanobiphenyl (5CB) is inserted in an external-cavity semiconductor laser as the fine-tuning element of wavelength. Varying the voltage biasing the NLC cell, its extraordinary index of refraction would change due to field-induced reorientation of the LC director. This is equivalent to tune the laser cavity length. As a result, the laser wavelength can be continuously tuned. With a NLC cell 35.5 mum in thickness, the output frequency of the present laser can be tuned over 4 GHz for a 30-cm-long laser cavity without hopping. The driving rms voltage was less than 2 volts.
Analytical model for design criteria of passively Q-switched laser
(2001-03-01)
Chen, YF
;
Lan, YP
;
Chang, HL
;
電子物理學系
;
光電工程學系
A general and straightforward model was developed for the design of passively Q-switched lasers. With the second-threshold criterion and using a numerically fitting procedure, the output pulse energy was expressed as an analytical function of the initial transmission of the saturable absorber and the reflectivity of the output coupler. An analytical expression for the optimal output reflectivity was also obtained for maximizing the output pulse energy of a passively Q-switched laser with a given initial transmission of the saturable absorber. Excellent agreement was studied between the present results and detailed theoretical computations. A Nd:YAG laser with Cr4+:YAG as a saturable absorber was performed to illustrate the use of the present model.
Automatically controlled power equalizer for liquid crystal based optical demultiplexer
(2005)
Lan, YP
;
Lai, YF
;
Pan, RP
;
Pan, CL
;
交大名義發表
Power equalization of four channels for a liquid crystal based demultiplexer by automatically controlling the liquid crystal pixels is demonstrated. The variation between different channels reduced from 10 dB to 0.15 dB.
Compact efficient intracavity optical parametric oscillator with a passively Q-switched Nd : YVO4/Cr4+: YAG laser in a hemispherical cavity
(2003-10-01)
Chen, YF
;
Chen, SW
;
Chen, YC
;
Lan, YP
;
Tsai, SW
A compact eye-safe optical parametric oscillator (OPO) using a noncritically phase-matched KTP crystal intracavity pumped by a passively Q-switched Nd: YVO4 laser is experimentally demonstrated. To enhance the performance of passive Q-switching, a Cr4+: YAG saturable absorber crystal is coated as an OPO output coupler in a nearly hemispherical cavity. With an incident pump power of 2.5 W, the compact intracavity OPO cavity, operating at 62.5 kHz, produces average powers at 1573 nm up to 255 mW and peak powers higher than 1 kW.
Comparison between c-cut and A-cut Nd : YVO4 lasers passively Q-switched with a Cr4+: YAG saturable absorber
(2002-04-01)
Chen, YF
;
Lan, YP
;
電子物理學系
;
光電工程學系
;
Department of Electrophysics
Comparison between c-cut and a-cut Nd:YVO4 microchip lasers passively Q-switched with a Cr4+:YAG saturable absorber is experimentally made. The lower emission cross section of the c-cut Nd:YVO4 crystal can enhance the passive Q-switching effect to produce a peak power 10 times higher than that obtained with the a-cut crystal. The experimental result further reveals that a c-cut Nd:YVO4 crystal is a very convenient material for short-pulse (sub-nanosecond) and high-peak-power (> 10 kW) lasers.
Design of efficient high-gower diode-end-pumped TEMoo Nd : YVO4 laser
(2000)
Chen, YF
;
Liao, CC
;
Lan, YP
;
Wang, SC
;
電子物理學系
A systematic investigation on a series of Nd:YVO4 crystals with different dopant concentrations is conducted to scale the diode-end-pumped laser performance to higher powers. The analysis reveals that lowering the dopant concentration linearly extends the fracture-limited pump power and the thermal shock parameter plays an important role in the estimation of the fracture-limited pump power: The thermal shock parameter in Nd:YVO4 crystals has been determined from the laser experiments, Based onthe analysis, we demonstrate a compact and efficient diode-end-pumped TEMoo laser with output power of 25.2-W for 52-W of incident pump power by use of a single YVO4 crystal with a Nd concentration of 0.3 at.%. In Q-switched operation 2 I-W of average power at a pulse repetition rate of 100 kHz and similar to 1.1-m pulse energy at a pulse repetition rate of 10 kHz were produced.
Determination of the Auger upconversion rate in fiber-coupled diode end-pumped Nd : YAG and Nd : YVO4 crystals
(2000-04-01)
Chen, YF
;
Liao, CC
;
Lan, YP
;
Wang, SC
;
電子物理學系
An analytical model is developed to study the influence of the Auger upconversion process on the thermal loading under lasing and nonlasing conditions. With the developed model, Auger upconversion rates can be determined by comparing theoretical calculations with experimental results for the ratio of the thermal loading under lasing and nonlasing conditions. The upconversion rates obtained with the present method are compared with the results measured from the fluorescence decay experiment.
Diode-end-pumped passively mode-locked high-power Nd : YVO4 laser with a relaxed saturable Bragg reflector
(2001-02-15)
Chen, YF
;
Tsai, SW
;
Lan, YP
;
Wang, SC
;
Huang, KF
We demonstrate a high-power passively mode-locked Nd:YVO4 laser that uses a saturable Bragg reflector (SBR) with strain relaxation. 23.5 W of average power with similar to 21.5-ps cw mode-locked pulse trains was generated at a 50-W pump power. Experimental results show that appropriate strain relaxation in the SBR makes the mode-locking operation less sensitive to temperature variation. (C) 2001 Optical Society of America OCIS codes: 140.3530, 140.3580, 140.4050, 140.7090, 160.6000.
Diode-pumped passively Q-switched Nd : YAG laser at 1123 nm
(2004-07-01)
Chen, YF
;
Lan, YP
;
電子物理學系
;
Department of Electrophysics
A diode-pumped Nd : YAG laser at 1123 nm is passively Q-switched by using a low doping concentration Cr4+ : YAG crystal as a saturable absorber. When pumped by a 1.5-W laser diode, the laser produces pulses of 50-ns duration with a pulse energy of as much as 15 muJ and a peak power of 300 W at a pulse-repetition rate of 10 kHz.
Dynamics of helical-wave emission in a fiber-coupled diode end-pumped solid-state laser
(2001-07-01)
Chen, YF
;
Lan, YP
;
電子物理學系
;
光電工程學系
;
Department of Electrophysics
We have generated TEM0,l* modes in an end-pumped microchip laser using a standard fiber-coupled diode. A rich set of dynamic behaviors, such as periodic and quasiperiodic self-modulation, chaotic pulsing and frequency locking was observed in the generated TEM0,l* modes. Experimental results confirm the theoretical predictions that the locking occurs as a subcritical bifurcation and that a region of coexisting locked and unlocked states exists.
Dynamics of Laguerre Gaussian TEMo,l* mode in a solid-state laser
(2002)
Lan, YP
;
Wang, SC
;
Chen, YF
;
光電工程學系
;
Department of Photonics
The dynamics of a solid-state laser sustaining the oscillation of the Laguerre-Gaussian TEM*(0.1) mode is experimentally studied. The results are given of investigations of the existence conditions of self-modulation, chaotic, frequency locking, and self-pulsing regimes. From the observations of the locking phenomena of the first order family occurs as a subcritical bifurcation in a solid-state laser.
Dynamics of the Laguerre Gaussian TEM0,l* mode in a solid-state laser
(2001-06-01)
Chen, YF
;
Lan, YP
;
電子物理學系
;
光電工程研究所
;
Department of Electrophysics
The dynamics of a solid-state laser sustaining the oscillation of the Laguerre-Gaussian TEM*(0,l) mode is theoretically and experimentally studied. The results of investigations of the existence conditions of self-modulation, chaotic. frequency locking, and self-pulsing regimes are given. The experimental results, obtained using a diode-pumped solid-state laser, are well confirmed by the theoretical model. From the observations of the locking phenomena of the first-order family, we also confirm the theoretical predictions that the locking occurs as a subcritical bifurcation in a solid-state laser.
Efficient high-power diode-end-pumped TEM00 Nd : YVO4 laser
(1999-10-01)
Chen, YF
;
Huang, TM
;
Liao, CC
;
Lan, YP
;
Wang, SC
We demonstrate a compact and efficient diode-end-pumped TEM00 laser with output power of 25.2 W for 52 W of incident pump power by use of a single YVO4 crystal with a Nd concentration of 0.3 at.%. In Q-switched operation 21-W of average power at a pulse repetition rate of 100 kHz and similar to 1.1-mJ pulse energy at a pulse repetition rate of 10 kHz were produced, At 10 kHz, the pulse width is around 10 ns and the peak power is higher than 100 kW.
Efficient high-power diode-end-pumped TEM00 Nd : YVO4 laser with a planar cavity
(2000-07-15)
Chen, YF
;
Lan, YP
;
Wang, SC
;
電子物理學系
;
光電工程學系
We demonstrate a compact and efficient diode-end-pumped TEMinfinity laser with output power of 30 W for 48 W of incident pump power by use of two coated Nd:YVO4 crystals to form a thermally stabilized flat-flat cavity. In Q-switched operation 25 W of average power at a pulse-repetition rate of 100 kHz and similar to 0.9-mJ pulse energy at a pulse-repetition rate of 10 kHz were produced. (C) 2000 Optical Society of America OCIS codes: 140.3480, 140.3540.
Fine-tuning of a diode laser wavelength with a liquid crystal intracavity element
(2004-01-01)
Lan, YP
;
Chen, CY
;
Pan, RP
;
Pan, CL
;
電子物理學系
A novel and simple approach for fine-tuning a laser wavelength is proposed and demonstrated. The key element is a planarly aligned nematic liquid crystal (NLC) cell inserted between the grating and end mirror of an external-cavity semiconductor laser (ECL). Varying the voltage driving the NLC cell, causes its extraordinary index of refraction to change due to field-induced reorientation of the LC director. This is equivalent to tuning the laser cavity length. As a result, the laser wavelength can be continuously tuned. With a 35.5-/mum-thick NLC cell, the output frequency of the present laser can be continuously tuned over 4 GHz. The root mean square driving voltage required is 1.5 V or less. The tuning range is in good agreement with the theoretical predictions. (C) 2004 Society of Photo-Optical Instrumentation Engineers.
Formation of optical vortex lattices in solid-state microchip lasers: Spontaneous transverse mode locking
(2001-12-01)
Chen, YF
;
Lan, YP
;
電子物理學系
;
光電工程研究所
;
Department of Electrophysics
We experimentally investigate pattern formation in a solid-state microchip laser with a large Fresnel number. Controlling the reflectivity of the output coupler can generate the stable square pattern of optical vortex lattices. The formation of square vortex lattices is found to be a spontaneous process of transverse mode locking within almost-degenerated mode families. The frequency of self-induced oscillation in square vortex lattices agrees well with the numerical calculation. The chaotic relaxation oscillation is found in square vortex lattices due to the multi-longitudinal-mode operation.
Formation of repetitively nanosecond spatial solitons in a saturable absorber Q-switched laser
(2004-07-02)
Chen, YF
;
Lan, YP
;
電子物理學系
;
Department of Electrophysics
We report on an experimental observation of repetitively nanosecond spatial solitons in a saturable absorber Q-switched microchip laser. The formation of high-peak-power spatial localized structures is achieved by controlling the self-focusing effect in a nearly hemispherical resonator. Our experimental results not only show qualitative agreement with theoretical predictions but also give quantitative criteria for the self-focusing nonlinearity. In addition, we also observe the coexistence of amplitude and phase solitons.
Generation of Laguerre-Gaussian modes in fiber-coupled laser diode end-pumped lasers
(2001-01-01)
Chen, YF
;
Lan, YP
;
Wang, SC
;
電子物理學系
;
光電工程學系
A technique has been developed for the generation of Laguerre-Gaussian (LG(0,l)) modes in a fiber-coupled laser diode end-pumped microchip laser. A theoretical model is also developed to predict how the oscillation of LG(0,l) modes is affected by the pump position, the pump size and the cavity mode size. With a l-W fiber-coupled diode, the highest-order LG(0,l) mode that can be generated is l = 23.
High-power diode-end-pumped Nd : YVO4 laser: thermally induced fracture versus pump-wavelength sensitivity
(2000-12-01)
Chen, YF
;
Lan, YP
;
Wang, SC
;
電子物理學系
;
光電工程學系
We report two kinds of compact and efficient diode-end-pumped TEM00 lasers with output power > 25 W at approximate to 50 W of incident pump power. One laser consists of a single 0.3 at. % Nd:YVO4 crystal in a V-type cavity, the other laser includes two 0.5 at. % Nd:YVO4 crystals in a linear cavity. Experimental results show that lowering Nd3+ concentration can be beneficial in extending the fracture-limited pump power but it also increases the sensitivity of the pump wavelength due to the overlapping efficiency.
High-power diode-end-pumped passively mode-locked Nd : YVO4 laser with a relaxed saturable Bragg reflector
(2002)
Tsai, SW
;
Lan, YP
;
Wang, SC
;
Huang, KF
;
Chen, YF
We present an efficient diode-end-pumped passively mode-locked Nd:YVO4 laser with a relaxed single-quantum-well saturable Bragg reflector (SBR), which average output power is more than 23 W and pulse duration 21.5 ps cw mode-locking is generated corresponding to 50 W pumping power. The overall optical-optical efficiency reaches 47% and to our knowledge, this is the highest conversion efficiency ever reported for passively mode-locked laser with average output power over 20 W. In this experiment, the broad absorption spectrum of the relaxed SBR leads a mode-locking operation to less sensitive to temperature variation. The output power corresponding to the transition from cw operation to QML and QML to CWML were also investigated. We believe the high reliability and stability of this mode-locked laser with a relaxed SBR will be interesting in laser application.