摘要:

Highly nondegenerate four‐wave mixing (&dgr;&ohgr;>100 GHz) has been observed in GaAlAs semiconductor lasers in the case where each of the pump, probe, and conjugate frequencies is close to that of a cavity mode. The high measured reflectivities (∼1000) have been demonstrated to depend on the relative position of the pump and probe cavity resonances. When the probe frequency was tuned, probe and conjugate spectra exhibited resonances on the cavity modes lying near the probe and conjugate frequencies. Such experiments may greatly help both in the modeling of laser action and in the measurement of laser parameters.

ISSN:0003-6951    

DOI:10.1063/1.101865

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We investigate the timing jitter in gain‐switched Fabry–Perot (FP) and distributed feedback (DFB) lasers based on the Langevin equations. Numerical results are in good agreement with measured ones. The present analysis demonstrates that the difference between the timing jitter in FP lasers and that in DFB lasers is caused by the difference in rapidity of turn‐on.

ISSN:0003-6951    

DOI:10.1063/1.101866

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We have developed a powerful and efficient mode‐locked andQ‐switched diode laser pumped Nd:YAG laser. Mode locking has been accomplished using intracavity frequency modulation (FM) to produce continuous‐wave mode‐locked pulses of 12 ps duration. Acousto‐optic pre‐laseQswitching has produced a train of pulses of about 25 ps average duration at a repetition rate of 360 MHz in an envelope of 75 ns duration. When pumped with a 500 mW diode laser array, the energy in theQ‐switched envelope was 15 &mgr;J giving a peak power in the largest pulse of 19 kW. The laser has been frequency doubled in a crystal of potassium titanyl phosphate (KTP) with an efficiency of 36%. The doubled radiation at 532 nm has been used to synchronously pump a mode‐locked rhodamine 6G dye laser to produce a train of tunable pulses. The pulse duration of the dye laser was 3.2 ps and the peak power of the largest pulse in the train was 10 kW.

ISSN:0003-6951    

DOI:10.1063/1.101867

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

An accurate, sensitive, easily implemented method of calibration of the elastic displacement of piezoelectric transducers used in scanning tunneling microscopes has been developed. The axial displacement for both static and harmonic excitation has been measured using laser beam deflection amplified by an optical magnification system. For harmonic excitation where lock‐in amplifier detection can be utilized, displacements as small as 0.03 A˚ have been measured. Measurements on PZT‐5H and PZT‐8 transducers over a range of five orders of magnitude in applied voltage demonstrate the power of the method in calibration of displacements from the subangstrom to the nonlinear region with an uncertainty of about 4%.

ISSN:0003-6951    

DOI:10.1063/1.101868

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report the first integrated injection‐locked high‐power continuous‐wave diode laser array with an on‐chip independently controlled master laser. This device emits a near‐diffraction‐limited (0.5° full width at half maximum) single‐lobed far‐field emission beam at single‐facet powers up to 125 mW. Also, by current tuning the emission wavelength of the master laser, we observe steering of the single‐lobed emission over an angular range of 0.50° at a rate of −1.2×10−2deg/mA. Our work demonstrates the feasibility of incorporating active optical injection and control in the structure of high‐power diode laser devices.

ISSN:0003-6951    

DOI:10.1063/1.101845

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The influence of the substitution positions of donors and acceptors on quadratic hyperpolarizabilities (&bgr;) was simulated by the AM1 method using four types of conjugated long‐chain molecules having polydiacetylene structures. The chain‐length dependences of &bgr; are greatly affected by the molecular type. The molecule, in which donor‐donor pairs and acceptor‐acceptor pairs alternately appear in the chain, has a narrow energy gap of about 1.6 eV and an exceptionally large &bgr; per 10 A˚ chain length, about 110 times larger than &bgr; of 2‐methyl‐4‐nitroaniline.

ISSN:0003-6951    

DOI:10.1063/1.101846

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We describe the structure and operating characteristics of a high‐speed optically addressed spatial light modulator (OASLM) with a hydrogenated amorphous silicon (a‐Si:H) photosensor and a ferroelectric liquid‐crystal modulator. The photosensor is ap‐i‐nphotodiode, which switches the liquid crystal into one of two stable states. Under a write‐light intensity of 6 mW/cm2, the OASLM exhibits a response time of 155 &mgr;s, a contrast ratio of 20:1, and a resolution of 40 lp/mm. The writing sensitivity per pixel is 0.1 pJ.

ISSN:0003-6951    

DOI:10.1063/1.101847

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Integrated external cavity GaAs/AlGaAs single quantum well lasers were fabricated by selective quantum well disordering. Lasers with 2.07‐mm‐long passive sections and 0.48‐mm‐long active sections had threshold currents of 33 mA, compared to 9.8 mA for lasers without passive sections. Lasing data indicate a residual modal loss of 11 cm−1in the passive sections, consistent with direct waveguide loss measurements. Control composite structures with a nondisordered quantum well in the passive sections showed significantly higher threshold currents and a large red shift of as much as 11.4 nm in the lasing wavelength compared to lasers without a passive cavity. This red shift is the main reason for the reduced resonant losses in integrated external cavity lasers with a nondisordered quantum well in the passive section.

ISSN:0003-6951    

DOI:10.1063/1.101848

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A method is described for transmission of images through a distorter. The technique uses the principle of phase conjugation and employs two holograms. The conjugate of one of the reference beams acts as a carrier for the signal through the distorting medium.

ISSN:0003-6951    

DOI:10.1063/1.101849

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The pronounced photorefractive effect in La3Ga5SiO14‐Pr3+crystals has been revealed. This is the first observation of the photorefraction caused by the bulk photovoltaic effect in a piezoelectric crystal. In accordance with symmetry features of the bulk photovoltaic effect in trigonal La3Ga5SiO14‐Pr3+, a value and a sign of the photorefraction depend on the orientation of an inducing light polarization vector. Experimental photorefraction data are in good agreement with phenomenological description. The discovered phenomenon may lead to interesting peculiarities in photorefractive recording and adaptive optics.

ISSN:0003-6951    

DOI:10.1063/1.102432

出版商:AIP    

年代:1989

数据来源: AIP