摘要:

Amplification characteristics of erbium‐doped optical fiber amplifier have been investigated using femtosecond soliton pulses with various wavelengths. Soliton trapping is not observed for 210 fs input pulses at 1.535 &mgr;m but the soliton self‐frequency shift occurs along with the pulse‐width narrowing. When the input pulse width is 470 fs, the soliton pulse is amplified by the optical gain at 1.535 &mgr;m, where the gain bandwidth is broader than the bandwidth of the input pulse. Amplification characteristics at other nonresonant wavelengths are also investigated using a femtosecond soliton pulse.

ISSN:0003-6951    

DOI:10.1063/1.104758

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A novel beam steering device using gratings integrated on rib waveguides as input and output couplers is proposed. Phasing is achieved electro‐optically by applying an electric field on an indium‐tin‐oxide/AlGaAs Schottky junction. A two elements device is first used to characterize the phase modulation characteristics of the structure. A 43 elements device with sawtooth electrodes is then presented, that permits spatial three‐point digital beam steering or amplitude modulation. The outcoupled beams have an angular width of 1.8 mrad full width at half maximum. The switched beam angular separation is 9 mrad, the switching voltage is −21 V.

ISSN:0003-6951    

DOI:10.1063/1.104759

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report a 27:1 switching contrast ratio with 2.5 mW of power in an asymmetric Fabry–Perot e´talon. The modulation is achieved by optical saturation of the excitonic absorption profile of a 95 A˚ GaAs/AlGaAs multiple quantum well structure grown on a high‐reflectivity dielectric stack mirror.

ISSN:0003-6951    

DOI:10.1063/1.104734

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report on double‐phase conjugation at 1.06 &mgr;m wavelength in InP:Fe with applied continuous electric field. Conversion efficiencies up to 74% with a grating period of 9 &mgr;m are obtained. The dependence of this efficiency on intensity, applied field, and grating period is reported and the results are compared with numerical simulations taking into account space‐charge field nonlinearities. Double color (1.06 and 1.32 &mgr;m) pumped oscillation is also observed with conversion efficiencies higher than 30%.

ISSN:0003-6951    

DOI:10.1063/1.104735

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

To investigate shock wave propagation in air, optical pulses with temporal separations ranging from 53 to 425 ns have been generated for use in double‐exposure pulsed holography using a White cell [J. U. White, J. Opt. Soc. Am.32, 285 (1942)] as an optical delay element. A single optical pulse from aQ‐switched Nd:YAG laser was split using polarizing optics so that one pulse was guided directly to the experimental holographic recording setup; the other pulse was sent first into the White cell, emerging a set number of nanoseconds later. This delayed pulse then was used to record a second holographic exposure. Using the White cell construction, reproducible pulse separations between 53 and 425 ns could be generated. Shock wavefronts propagating at velocities greater than Mach 20 have been recorded using this method.

ISSN:0003-6951    

DOI:10.1063/1.104736

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The production of a near‐diffraction‐limited single‐lobed angle‐switchable output beam from a broad‐area diode laser with an intracavity spatial phase controller is demonstrated. This 100‐&mgr;m‐wide broad‐area laser produces a 0.8° full width at half maximum output beam at single‐facet pulsed powers of ≳300 mW. The spatial phase controller operates in two distinct modes (thermal and gain), providing beam scanning over 1.4° and beam switching of 8°. The phase controller also permits a dynamic study of the effect of wavefront tilt on device coupling and phasing.

ISSN:0003-6951    

DOI:10.1063/1.104737

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We demonstrate all‐optical nonlinearities at low cw pump powers (50 W/cm2) using a novel heterostructure design which spatially separates photoexcited electron‐hole pairs. Theoretical calculations based on many‐body interactions are in good agreement with the measured spectra.

ISSN:0003-6951    

DOI:10.1063/1.104738

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A novel structure, in which the potential profile of the coupled quantum well system is slightly inclined, is proposed for lowering the electric field required to transform the coupled system to a set of uncoupled single quantum wells. Numerical calculations of absorption spectra of graded coupled quantum wells under an electric field and room‐temperature photocurrent spectra of fabricatedp‐i‐ndiode samples confirm the above enhanced effect.

ISSN:0003-6951    

DOI:10.1063/1.104713

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Continuous‐wave laser radiation from an argon‐ion laser in the wavelength range 300–330 <m1;&3.6>nm or 350–380 nm, when focused to a spot such that the power density is ∼10 kW/cm2, can be used to etch polyimide (DuPont KaptonTM) films with as little thermal damage as from an excimer laser (308 or 351 nm) provided the laser spot is moved over the surface at speeds at which the transit time over its own diameter is in the order of 1–1000 &mgr;s. There is an optimum speed at which the cutting action is a maximum for a given power density per unit area. The fluence (in J/cm2) at which etching occurs is comparable to results obtained with excimer laser pulses but the depth of the material that is removed per joule of incident laser is energy is ∼100‐fold less. In the present process there is no ablation and no acoustic report accompanies it. Only a fraction of the polyimide that is removed from the surface is seen as debris.

ISSN:0003-6951    

DOI:10.1063/1.104714

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Reactive ion etching of polycrystalline silicon using SiCl4was used to etch 70‐nm‐wide structures. The etching mechanism of the process was investigated by using emission spectroscopy. It was found that the principal etchant for polycrystalline silicon is Cl+2.

ISSN:0003-6951    

DOI:10.1063/1.104715

出版商:AIP    

年代:1991

数据来源: AIP