摘要:

A substantial enhancement (by orders of magnitude) of the Sagnac effect in a passive ring resonator can be attained by using a nonreciprocal feedback. This feedback is based on the nonreciprocal element controlled by the signal proportional to the difference between intensities of counterpropagating waves, and is an optoelectronic analog of nonlinear nonreciprocity proposed by us earlier. Under some critical conditions, this system can exhibit directional bistability and directional switching of the counterpropagating waves.

ISSN:0003-6951    

DOI:10.1063/1.94000

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Optoelectronic correlations between twon‐GaAs metal‐semiconductor‐metal photodetectors were measured. An arrangement of two photosensing areas, each having a separation of far less than the minimum possible wavelength on the stripline, was examined. The equivalent circuit analysis clearly explained the observed correlation signals and revealed the limits of the photodetector response.

ISSN:0003-6951    

DOI:10.1063/1.94001

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The laser power required to record high contrast marks in a polymer film can be reduced two orders of magnitude by depositing the film on a transparent conductor‐photoconductor‐conductor sandwich. The sensitivity of this medium is controlled by adjusting the voltage applied to the conductors. In the power limited regime, as little as 0.1 mW of laser power can increase the ohmic heating at the focus enough to produce symmetric micrometer size bubbles in the adjacent polymer film without damaging the photoconductor. However, due to the high dark resistivity of the photoconductor, the power dissipation in the unilluminated region is only ≊0.01 W/cm2.

ISSN:0003-6951    

DOI:10.1063/1.93976

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Continuous (cw) 300‐K laser operation of a 66‐period lower energy GaAs‐InxGa1−xAs (x∼0.2) strained superlattice (SL) and a higher energy 128‐period GaAs1−xPx‐GaAs (x∼0.25) strained SL is demonstrated. The strained SL’s are grown by organometallic vapor phase epitaxy (OMVPE) or metalorganic chemical vapor deposition (MOCVD) with higher gap quaternary confining layers andLB∼75 A˚ barriers andLz∼75 A˚ quantum wells. These SL’s are unstable during high level excitation, failing in 2–20 min when operated cw at 300 K as photopumped lasers.

ISSN:0003-6951    

DOI:10.1063/1.93977

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Upconversion by mixing of optical parametric light with the fourth harmonic of a neodymium:yttrium aluminum garnet (Nd:YAG) laser and fourth harmonic pumped H2and N2Raman light has been used to generate high‐power picosecond continuously tunable UV light ranging from 215–245 nm with an energy of more than 100 &mgr;J. The tunability is based on generation of optical parametric light with a range from 900 to 1400 nm.

ISSN:0003-6951    

DOI:10.1063/1.93978

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Gratings of dielectric material can act as homogeneous birefringent materials if the wavelength of the incident radiation is greater than twice the period of the grating. For the case of square profile gratings, simple equations predict the birefringence versus linewidth‐to‐period ratio of the gratings. By using x‐ray lithography and reactive ion etching, 240‐nm period gratings of polymethylmethacrylate and silicon nitride were fabricated with various linewidths. The birefringence of these was measured at 632.8 nm and found to agree closely with the theory. Silicon nitride gratings which act as half‐wave and quarter‐wave plates in the visible were made.

ISSN:0003-6951    

DOI:10.1063/1.93979

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A gain‐guided phase‐locked semiconductor laser array has been observed to emit a single narrow lobed far‐field radiation pattern up to 70 mW, at which power level it exhibits a distinct change. We show that this effect results from a new phase‐locked mode attaining threshold; the original mode remains phase locked above this power level.

ISSN:0003-6951    

DOI:10.1063/1.93980

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The diffusion coefficients of nitrogen in polycrystalline &agr;‐Ti have been measured by annealing nitrogen‐implanted titanium samples in the low‐temperature region, i.e., 450–700 °C. The nitrogen profiles were probed with the ( p,&ggr;) resonance broadening method. The implantation energies were 20–60 keV and the fluences were 1016–1018ion/cm2, corresponding to 1.4 and 14 at. % at the maximum of the N profile, respectively. The concentration change had only a slight effect on the diffusivity. The irradiation effect on the diffusivity was studied by bombarding the samples with 20–60 keV22Ne+ions with 1016–1018ion/cm2fluences and 600–keV protons with a 1018proton/cm2fluence. However, no significant change was observed.

ISSN:0003-6951    

DOI:10.1063/1.93981

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Epitaxial single‐crystal growth of Si films has been achieved on the (100), (110), and (111) planes of yttria‐stabilized, cubic zirconia single crystals. The Si films were grown by the pyrolysis of SiH4at temperatures in the range 950–1075 °C and at deposition rates of 0.08–1.2 &mgr;m/min. The structural and electrical properties of the Si films have been determined by Rutherford backscattering and channeling, x‐ray diffraction, and Hall effect measurements. Several 0.4–0.5‐&mgr;m‐thick (100) and (110) Si films on cubic zirconia were found to be of higher crystal quality than commercial (100) Si‐on‐sapphire films of similar thickness.

ISSN:0003-6951    

DOI:10.1063/1.93982

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The phase transformation induced by a picosecond laser pulse in implanted amorphized silicon has been studied. A single 30‐ps pulse at 1.06‐ and 0.532‐&mgr;m wavelengths from a mode‐locked neodymium:yttrium aluminum garnet laser was used to generate a multiannular (up to five rings) recrystallization pattern on an implanted silicon substrate. A Raman microprobe with a 1‐&mgr;m spatial resolution was utilized to investigate the annealed spots. These measurements combined with polarized light scattering experiments resulted in a detailed spatial analysis (parallel and perpendicular to the surface) of the recrystallization pattern, that was related to the picosecond laser energy and wavelength. At high incident energies single crystal silicon is observed in the central spot and in the first recrystallized ring of the annealed area.

ISSN:0003-6951    

DOI:10.1063/1.93983

出版商:AIP    

年代:1983

数据来源: AIP