Diode-pumped room-temperature continuous wave Tm3+ doped Lu2SiO5 laser

We report on room temperature laser actions of a novel thulium-doped crystal Tm center dot Lu2SiO5 (LSO) under diode pumping. An optical optical conversion efficiency of 12% and a slope efficiency of 21% were obtained with the maximum continuous wave (CW) output power of 0.67 W. The emission wavelengths of Tm LSO laser were centered at 2058.4 nm with bandwidth of similar to 13.6 nm.

Holmium laser in-band pumped by a thulium laser in the same host of YAlO3

We report on the room-temperature continuous-wave (CW) operation of a Ho:YAlO3 laser that is resonantly end pumped at 1.94 mu m by a diode-pumped thulium-doped laser in the same host. Through the use of a 1 at % Ho3+-doped 20-mm-long YAlO3 crystal (b cut), the Ho:YAlO3 laser generated 1 W of linearly polarized (E//c) output at 2118 nm and 0.55 W of E//a output at 2128.5 nm for an incident pump power of 5 W, with an output coupler transmission of 14 and 3%, respectively. An optical-to-optical conversion efficiency of 20% and a slope efficiency of 33% were achieved at 2118 nm corresponding to an incident pump power.

Continuous-wave and passively mode-locked Yb : GYSO lasers pumped by diode lasers

We report both continuous-wave and passively mode-locked laser actions in a Yb3+-doped gadolinium yttrium oxyorthosilicate Yb:GdySiO(5) (Yb:GYSO) crystal. Continuous-wave (CW) laser operations were compared under different pump conditions with high-power diodes of different wavelengths and fiber cores. CW mode-locking was obtained with a semiconductor saturable absorber mirror.

Continuous-wave and Q-switched operation of a resonantly pumped Ho:YAlO3 laser

We demonstrated continuous-wave ( CW) and Q-switched operation of a room-temperature Ho: YAlO3 laser that is resonantly end-pumped by a diode-pumped Tm: YLF laser at 1.91 mu m. The CW Ho: YAlO3 laser generated 5.5 W of linearly polarized (E parallel to c) output at 2118 nm with beam quality factor of M-2 approximate to 1.1 for an incident pump power of 13.8 W, corresponding to optical-to-optical conversion efficiency of 40%. Up to 1-mJ energy per pulse at pulse repetition frequency (PRF) of 5 kHz, and the maximum average power of 5.3-W with FWHM pulse duration of 30.5 ns at 20 kHz were achieved in Q-switched mode. (C) 2008 Optical Society of America.

Continuous-wave operation of GaN based multi-quantum-well laser diode at room temperature

Room-temperature operation of cw GaN based multi-quantum-well laser diodes (LDs) is demonstrated. The LD structure is grown on a sapphire (0001) substrate by metalorganic chemical vapour deposition. A 2.5 mu m x 800 mu m ridge waveguide structure is fabricated. The electrical and optical characteristics of the laser diode under direct current injection at room temperature are investigated. The threshold current and voltage of the LD under cw operation are 110mA and 10.5V, respectively. Thermal induced series resistance decrease and emission wavelength red-shift are observed as the injection current is increased. The full width at half maximum for the parallel and perpendicular far field pattern (FFP) are 12 degrees and 32 degrees, respectively.

Phosphor-conversion white light using InGaN ultraviolet laser diode

We fabricated a phosphor-conversion white light using an InGaN laser diode that emits 405 nm near-ultraviolet (n-UV) light and phosphors that emit in the blue and yellow regions when excited by the n-UV and blue light, respectively.The relationship of the luminous flux and the luminous efficacy of the white light with injection current was discussed. The luminous flux increased linearly with increasing current above the threshold of the laser diode, and at 80 mA injection current, the luminous flux and luminous efficacy were estimated to be 5.7 lm and 13 lm/w, respectively. The shift of the Commission International de I'Eclairage coordinates, color temperature, and color rendering index with current are very slight and negligible, which indicates that the blue and the yellow phosphors have an excellent stability and a highly stable white light can be obtained by this way. (c) 2008 American Institute of Physics.

Characterization of parasitics from scattering parameters of laser diode

A novel method for characterizing the parasitics of parasitic network is proposed based on the relations between the scattering parameters of a semiconductor laser chip and laser diode. Experiments are designed and performed using our method. The analysis results are in good agreement with the measurements. Furthermore, how the parasitics change with the parasitic element values are investigated. The method only needs reflection coefficient of laser diode to be measured, which is simple because of the developed electrical-domain measurement techniques. 2007 Wiley Periodicals, Inc.

Narrow-Linewidth Microwave Generation Using a Self-Injected DBR Laser Diode

A novel technique for generating narrow-linewidth microwave or millimeter-wave signals is proposed. In this scheme, a delayed self-injected distributed Bragg reflector laser diode, which is tuned by a low-frequency square-wave voltage, is used to generate two correlated lightwaves simultaneously. Experiments show that the 10-dB linewidth of generated microwave signals is reduced from 147 MHz to 68 kHz utilizing the proposed self-injection technique.

The junction temperature and forward voltage relationship of GaN-based laser diode

In GaAs-based light-emitting diode (LED) or laser diode (LD), the forward voltage (V) will decrease linearly with the increasing junction temperature (T). This can be used as a convenient method to measure the junction temperature. In GaN-based LED, the relationship is linear too. But in GaN-based LD, the acceptor M (g) in p-GaN material can not ionize completely at-room temperature, and the carrier density will change with temperature. But we find finally that, this change won't lead to a nonlinear relationship of V-T. Our experiments show that it is Linear too.

White light emission from ultraviolet laser diode

A phosphor-conversion white light using an InGaN laser diode that emits 405 nm near-ultraviolet (n-UV) light and phosphors that emit in the red/green/blue region when excited by the n-UV light was fabricated. The relationship of the luminous flux and the luminous efficacy of the white light with injection current were discussed. Based on the evaluation method for luminous efficacy of light sources established by the Commission International de I'Eclairage (CIE) and the phosphor used in this experiment, a theoretical analysis of the experiment results and the maximum luminous efficacy of this white light fabrication method were also presented.

Thermal effects investigation and cavity design in passively mode-locked Nd:YVO4 laser with a SESAM

A diode-pumped passively mode-locked Nd YVO4 laser with a five-mirror folded cavity is presented by using a semiconductor saturable absorber mirror (SESAM). The temperature distribution and thermal lensing in laser medium are numerically analyzed to design a special cavity which can keep the power density on SESAM under its damage threshold. Both the Q-switched and continuous-wave mode-locked operation are experimentally realized. The maximum average output power of 8.94 W with a 9.3 ps pulse width at a repetition rate of 111 MHz is obtained under a pump power of 24 W, correspondingly the optical slope efficiency is 39.2%. (C) 2008 Elsevier B.V. All rights reserved.

Passively mode-locked YVO4/Nd:YVO4 composite crystal green laser with a semiconductor saturable absorber mirror

A diode-pumped passively mode-locked YVO4/Nd YVO4 composite crystal green laser with a semiconductor saturable absorber mirror (SESAM) and a intracavity frequency-doubling KTP crystal was realized. The maximum average output power of 2.06 W at 532 nm with a repetition rate of 100 MHz was obtained at a pump power of 15 W, corresponding to optical slop efficiency 17.2%. The 532 nm mode-locked pulse width was estimated to be approximately 18-ps.

Analysis on the high luminous flux white light from GaN-based laser diode

We fabricated a phosphor-conversion white light using an InGaN laser diode that emits 445 nm and phosphor that emits in the yellow region when excited by the blue laser light. At 500 mA injection current the luminous flux and the luminous efficacy were 113 lm and 44 lm/W, respectively. The relationship of the luminous flux and the luminous efficacy of the white light with an injection current were discussed. Based on the evaluation method for luminous efficacy of light sources established by the Commission International de I'Eclairage (CIE) and the phosphor used in this experiment, a theoretical analysis of the experiment results and the maximum luminous efficacy of this white light fabrication method were also presented.

4-ps passively mode-locked Nd : Gd0.5Y0.5VO4 laser with a semiconductor saturable-absorber mirror

We have demonstrated a passively mode-locked diode end-pumped all-solid-state laser, which is composed of a Nd:Gd0.5Y0.5VO4 crystal and a folded cavity with a semiconductor saturable-absorber mirror grown by metal-organic chemical-vapor deposition. Stable cw mode locking with a 3.8-ps pulse duration at a repetition rate of 112 MHz was obtained. At 13.6 W of the incident pump power, a clean mode-locked fundamental-mode average output power of 3.9 W was achieved with an overall optical-to-optical efficiency of 29.0%, and the slope efficiency was 38.1%. (C) 2004 Optical Society of America.

GaAs-based room-temperature continuous-wave 1.59 mu m GaInNAsSb single-quantum-well laser diode grown by molecular-beam epitaxy

Starting from the growth of high-quality 1.3 mu m GaInNAs/GaAs quantum well (QW), the QW emission wavelength has been extended up to 1.55 mu m by a combination of lowering growth rate, using GaNAs barriers and incorporating some amount of Sb. The photoluminescence properties of 1.5 mu m range GaInNAsSb/GaNAs QWs are quite comparable to the 1.3 mu m QWs, revealing positive effect of Sb on improving the optical quality of the QWs. A 1.59 mu m lasing of a GaInNAsSb/GaNAs single-QW laser diode is obtained under continuous current injection at room temperature. The threshold current density is 2.6 kA/cm(2) with as-cleaved facet mirrors. (c) 2005 American Institute of Physics.