摘要:

Spectral broadening due to self‐phase modulation has been observed for ultrashort pulses propagating through an InGaAsP optical amplifier. This is not associated with gain saturation or absorption saturation, since it can be observed at the transparency current. At transparency, the broadening and structure of the spectra are symmetrical for pulses of approximately 27 ps duration, implying that the underlying nonlinearity has a relatively fast recovery time. The associated nonlinear index coefficientn2is estimated to be approximately −2×10−11cm2 W−1.

ISSN:0003-6951    

DOI:10.1063/1.104389

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Data are presented demonstrating a design and fabrication process for the realization of high‐efficiency, low‐threshold vertical‐cavity InGaAs‐GaAs quantum well lasers with light emission through the top (epitaxial) surface. Crystal growth is performed using a two‐step molecular beam epitaxial growth process to utilize lateral current injection into the device active region. The device structure allows the top surface (emission side) reflector to be optimized (for either high efficiency or low threshold) after crystal growth through the deposition of electron beam evaporated dielectric layers. Maximum continuous‐wave output power in excess of 1.2 mW at 300 K, and differential quantum efficiency greater than 25% (3.9 mA threshold) are demonstrated. Low‐threshold values of 2.3 mA are measured on devices with increased mirror reflectivity (through the addition of dielectric layers).

ISSN:0003-6951    

DOI:10.1063/1.104390

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The temperature dependence of threshold current of strained quantum well lasers is analyzed both experimentally and theoretically. The measurements are performed on ridge waveguide In0.2Ga0.8As/GaAs multiquantum well lasers emitting near 1 &mgr;m. The carrier densities at threshold of these lasers are measured using very short current pulse injection. A simplified calculation of the radiative, nonradiative recombination rates and the relationship between gain and carrier density in strained quantum well lasers is described. The results of the calculation are compared with experimental results.

ISSN:0003-6951    

DOI:10.1063/1.104391

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Third‐harmonic generation has been used to measure the magnitude and phase of the nonlinear susceptibility &khgr;(3)(3&ohgr;) of SiO2‐TiO2sol‐gel thin films as a function of TiO2concentration. Nonlinearities 20 times larger than those of fused silica were found, making such films useful for nonlinear optics in glass waveguides.

ISSN:0003-6951    

DOI:10.1063/1.104392

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The photoinduced refractive index change of polyester with disperse red side groups was studied at several different wavelengths. This material exhibits a large photoinduced index change (0.3 at 633 nm) and in addition when poled has a sizable second‐order nonlinear optical effect. This index change was monitored over 1000 h and long‐term stability was demonstrated. Based on these results, a method using only photomasks to define channel waveguides and other patterns in such polymers was suggested and experimentally demonstrated. This photoinduced index change may have wide applications in integrated optical systems when these or other similar polymers are involved.

ISSN:0003-6951    

DOI:10.1063/1.104393

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Carbon dioxide is used in induce glass transition in amorphous polymer films, allowing efficient alignment of chromophores with an applied electric field. The noncentrosymmetric films thus produced are capable of second‐harmonic generation. This method has advantages over previously investigated poling schemes, including poling at ambient temperatures and use of high glass transition temperature polymers.

ISSN:0003-6951    

DOI:10.1063/1.104394

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report a phase conjugate mirror (PCM) using germanium diselenide amorphous thin films with a 25 mW He Ne laser. The size of the PCM area can be made very large as opposed to the size limitations of crystal PCMs. The induced hologram may be recorded temporarily or permanently depending on the incident light parameters. The main drawback of this system is the long exposure time, of the order of minutes, required to generate the phase conjugate signal. The modulation of the refractive index is suggested to be due to a photostructural reorientation.

ISSN:0003-6951    

DOI:10.1063/1.104395

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Data are presented on operation of 100 &mgr;m aperture gain‐guided single quantum well laser diodes in an external grating cavity. A maximum power of 550 mW is coupled out of the cavity with an efficiency of 0.51 W/A. The laser emission has a linewidth of ≲1 A˚ and is tunable from 7950 to 8450 A˚ for the specific laser diodes used in this study. The output beam is collimated in the direction perpendicular to thep‐njunction, and exhibits a divergence of 0.4° parallel to thep‐njunction.

ISSN:0003-6951    

DOI:10.1063/1.104396

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The surface chemistry of GaAs‐oxide removal with an electron cyclotron resonance (ECR) hydrogen plasma has been investigated with x‐ray photoelectron spectroscopy. It is found that As oxide is efficiently removed at room temperature, and heating expedites the removal of Ga oxide. Band bending changes during ECR hydrogen‐plasma oxide reduction are also discussed.

ISSN:0003-6951    

DOI:10.1063/1.104397

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Light up‐conversion from red to green was performed in a new type of light transducer composed of an organic electroluminescent diode and a photoresponsive amorphous silicon carbide (a‐SiC:H) film as an electron photoinjecting electrode. Quantum efficiency of photon conversion reached 1% with the assistance of newly observed photocurrent multiplication ina‐SiC:H film.

ISSN:0003-6951    

DOI:10.1063/1.104398

出版商:AIP    

年代:1991

数据来源: AIP