摘要:

A high-power continuous-wave optical parametric oscillator based on the nonlinear materialKTiOAsO4and pumped internal to a tunable Ti:sapphire laser is described. The use of the intracavity pumping approach has enabled operation of a singly resonant oscillator (SRO), resulting in the generation of as much as 1.46 W of infrared power in a 11.5-mm-long crystal. Amplitude-stable signal and idler outputs, each in excess of 500 mW, over the respective wavelength ranges of 1.11–1.20 and 2.44–2.86 &mgr;m have been extracted from the SRO. We demonstrate up to 90&percent; down-conversion of the optimum Ti:sapphire output power to the SRO, confirming our recent theoretical predictions. The performance characteristics of the device demonstrate that practical, stable, and efficient operation of continuous-wave SROs at watt-level output power can be readily achieved in conventional birefringent materials by exploiting the intracavity pumping approach. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120572

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Optical resonance modes have been observed in optically pumped microdisk cavities fabricated from 50 Å/50 ÅGaN/AlxGa1−xN(x∼0.07)and 45 Å/45 ÅInxGa1−xN/GaN(x∼0.15)multiple quantum well structures. Microdisks, approximately 9 &mgr;m in diameter and regularly spaced every 50 &mgr;m, were formed by an ion beam etch process. Individual disks were pumped at 300 and 10 K with 290 nm laser pulses focused to a spot size much smaller than the disk diameter. Optical modes corresponding to (i) the radial mode type with a spacing of 49–51 meV (both TE and TM) and (ii) the Whispering Gallery mode with a spacing of 15–16 meV were observed in the GaN microdisk cavities. The spacings of these modes are consistent with those expected for modes within a resonant cavity of cylindrical symmetry, refractive index, and dimensions of the microdisks under investigation. The GaN-based microdisk cavity is compared with its GaAs counterpart and implications regarding future GaN-based microdisk lasers are discussed. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120573

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Humidity dependence of the refractive index of deuterated polymethylmethacylate (d-PMMA) is examined at a wavelength of 1.3 &mgr;m using the return loss method. The refractive index ofd-PMMA increases as humidity increases at room temperature, while it decreases as humidity increases at temperatures higher than 60 °C. This humidity dependence was ascribed to the counterbalance between moisture sorption and swelling. Some hydrophobic polymers, such as silicone resin and fluorinated epoxy resin were affected by humidity to a lesser degree thand-PMMA. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120574

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have fabricated photopumped distributed feedback lasers by spin-casting thin films of the semiconducting polymerpoly(2-butyl, 5-(2′-ethyl-hexyl)-1,4-phenylenevinylene)over gratings in silicon oxide. The lasers have two modes that each have a linewidth of 0.2 nm. The lasing wavelength was tuned from 540 to 583 nm by adjusting the period of the gratings. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121679

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Current-injection InGaAlN heterostructure laser diodes grown by metalorganic chemical vapor deposition on sapphire substrates are demonstrated with mirrors fabricated by chemically assisted ion beam etching. Due to the independent control of physical and chemical etching, smooth vertical sidewalls with a root-mean-squared roughness of 4–6 nm have been achieved. The diodes lased under pulsed current-injection conditions at wavelengths in the range from 419 to 423 nm. The lowest threshold current density was 25kA/cm2.Lasing was observed in both gain-guided and ridge-waveguide test diodes, with cavity lengths from 300 to 1000 &mgr;m; and output powers of 10–20 mW were achieved. Laser performance is illustrated with light output-current and current–voltage characteristics and with a high-resolution optical spectrum.©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120575

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Stable high-power operation in the uv is achieved from a commercial multi-kHz diode-pumped multimodeQ-switched Nd:YAG laser by fourth-harmonic generation in an external cavity. Over 640 mW at 266 nm in aTEM00beam and an internal conversion efficiency of 30&percent; were obtained. A lifetime of one-billion shots at several hundred mW and a long-term power stability of±1&percent;were recorded, demonstrating that this source has the potential of stable long-term operation using readily available components. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120576

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report on all-optical gating characteristics of a novel low-temperature-grown asymmetric Fabry–Perot (AFP) device, in which improvement of performance with respect to conventional AFP all-optical switches is achieved by a short and coupled cavity configuration. Sub-pJ(∼800 fJ)operation is realized with a high contrast ratio(>10 dB)over a broad wavelength range (∼7 nm). Even for 250 fJ pump pulses, a contrast ratio of>6 dBis obtained over a 4 nm wavelength range. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120577

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Persistent spectral hole burning is observed at room temperature in the excitation spectrum for the7F0→5D0transition ofSm2+inKLaF4single crystals. The hole width and depth are about10 cm−1and 18&percent; of the total intensity, respectively. It is concluded that the dominant burning mechanism in this crystal is a photoionization of electron trapping at a site other thanSm3+ions because of the absence of an antihole around the burned hole. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120578

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report on a resonant cavity photodiode with a Si/SiGe Bragg mirror grown by low temperature chemical vapor deposition suitable for short wavelength detection around 600–700 nm. The presence of Fabry-Pe´rot oscillations in the spectral response of the photodiode are indicative of its wavelength selectivity. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121111

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The laser characteristics of 1.3 &mgr;m tensile-strained InGaAsP/InP multi quantum well (MQW) lasers were studied. The tensile strain of well layers ranged from 0.5&percent; to 1.8&percent;. The level of the strain dependence of the threshold current shows that the threshold current decreases drastically with increase in the tensile strain from 0.5&percent; to 1.3&percent;, while it stays almost constant in the 1.45&percent;–1.8&percent; range. Among all the samples, the 1.3&percent; tensile-strained MQW laser shows superior performance in terms of minimum threshold current and maximum differential gain(∂g/∂N).The 1.3&percent; tensile strain is the optimum level for the tensile-strained MQW buried-heterostructure lasers. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121112

出版商:AIP    

年代:1998

数据来源: AIP