摘要:

A new type of laser structure which utilizes the selectively doped double‐heterojunction (SDH) structure for lateral current injection (LCI) was proposed. A ridge waveguide AlGaAs/GaAs laser based on the SDH‐LCI scheme was demonstrated to lase at the very low threshold current of 11.5 mA. The compatibility of this new laser structure with electronic devices is discussed.

ISSN:0003-6951    

DOI:10.1063/1.102477

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We show that color center induced absorption can mimic two‐photon absorption, and may limit all‐optical switching, even for very short pulses. Two‐photon and color center induced absorption are measured in a lead glass fiber.

ISSN:0003-6951    

DOI:10.1063/1.102478

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The operation of a very efficient, high‐energy DF‐CO2pulse chemical transfer laser is described. Laser specific energies as high as 21 J/l were obtained with a wall plug laser electrical efficiency of 130%. Higher laser energy can be obtained with lower efficiencies, e.g., 29 J/l at 80%. The electrical efficiency obtained herein is the highest reported to date for pulsed chemical lasers.

ISSN:0003-6951    

DOI:10.1063/1.102479

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new kind of distributed feedback (DFB) laser with a linearly chirped grating is proposed and investigated theoretically for the first time. The eigenmodes of the chirped grating DFB (CG‐DFB) and the field intensity distribution are calculated. With a suitable cavity length and chirp factor, the threshold gain difference to the next competence mode can be very large and will keep the single longitudinal mode stable. The chirp factor can be chosen to make the field intensity distribution quite uniform and at the same time keep the threshold gain difference large. This behavior effectively suppresses spatial hole burning and hence makes CG‐DFB lasers that are stable single mode at high power, and with a narrow linewidth.

ISSN:0003-6951    

DOI:10.1063/1.102480

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Hydrogenated amorphous silicon carbide (a‐SiC:H) films are prepared by the electron cyclotron resonance plasma chemical vapor deposition (ECR PCVD) technique. The films are, for the first time, applied as protective layers for phase‐change‐type optical disks. Three kinds of films with different hydrogen contents are investigated to improve writing sensitivity. The writing laser power required to obtain a sufficient carrier‐to‐noise ratio is 11 mW at a 10 m/s linear velocity, which corresponds to a 30% power reduction compared to conventional rf‐sputtered ZnS protective layers. This is attributed to the decreased thermal conductivity of these protective layers. The hydrogen in the films is confirmed to be thermally stable.

ISSN:0003-6951    

DOI:10.1063/1.102481

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have measured the nonlinear refractive index (n2) of single crystalline poly(bis(p‐toluene sulfonate) of 2,4‐hexadiyn‐1,6‐diol) (PTS) polydiacetylene channel waveguides at 1.06 &mgr;m using two different techniques. The first method employs a Mach–Zehnder interferometer to determine the intensity‐induced phase shift in the waveguide. In the second casen2is derived from the intensity‐dependent birefringence, which is measured with a Babinet–Soleil compensator. With both measurements the value ofn2in the direction of the PTS polymer chain axis is found to be ∼3×10−11cm2/W. Such a large value ofn2would allow all‐optical device applications of this material at low‐power levels.

ISSN:0003-6951    

DOI:10.1063/1.102482

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The condition for the fundamental mode operation in a single quantum well laser with vertically integrated passive waveguides has been studied. With proper choice of parameters, transverse beam divergence as low as 19° has been achieved.

ISSN:0003-6951    

DOI:10.1063/1.102483

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The minimum 248 nm, 25 ns, and 532 nm, 15 ns laser fluences required to blow off thin gold films from optical quartz have been measured as a function of film thickness. The films apparently blow off when the gold‐quartz interface reaches the normal boiling point of gold. Even though the initial reflectivities at the two wavelengths are very different, the actual laser fluences required to blow off the films are very similar. While the reflectivities above the melting point appear to be very low, as expected, large decreases in the reflectivity at 532 nm may also occur prior to film melting.

ISSN:0003-6951    

DOI:10.1063/1.102484

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new amplitude‐modulation mode‐locking technique is presented. Acoustic waves are generated directly on the faces of a resonant photoelastic medium. The created standing waves cause a highly efficient diffraction modulation of light. The modulation depth of standing‐wave mode lockers is related to material and drive parameters and a figure of merit is introduced. With a lithium niobate crystal modulation depths over 10 are achieved at 1.054 &mgr;m and 1 W of radio frequency power. Using this device for the active mode locking of a continuous‐wave Nd:glass laser pulses as short as 3.8 ps are produced at a repetition rate of 66 MHz. Limitations of amplitude‐modulation mode locking by standing acoustic waves are discussed.

ISSN:0003-6951    

DOI:10.1063/1.102485

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the successful growth of InAs/Ga1−xInxSb strained‐layer superlattices, which have been proposed for far‐infrared applications. The samples were grown by molecular beam epitaxy, and characterized by reflection high‐energy electron diffraction, x‐ray diffraction, and photoluminescence. Best structural quality is achieved for superlattices grown on thick, strain‐relaxed, GaSb buffer layers on GaAs substrates at fairly low substrate temperatures (<400 °C). Photoluminescence measurements indicate that the energy gaps of the strained‐layer superlattices are smaller than those of InAs/GaSb superlattices with the same layer thicknesses, in agreement with the theoretical predictions of Smith and Mailhiot [J. Appl. Phys.62, 2545 (1987)]. In the case of a 37 A˚/25 A˚, InAs/Ga0.75In0.25Sb superlattice, an energy gap of 140±40 meV (≊9 &mgr;m) is measured. This result demonstrates that far‐infrared cutoff wavelengths are compatible with short superlattice periods in this material system.

ISSN:0003-6951    

DOI:10.1063/1.102486

出版商:AIP    

年代:1990

数据来源: AIP