摘要:

The nonresonant third‐order nonlinear optical properties of thin films of poly(p‐phenylene benzobisthiazole) (PBZT) and PBZT/nylon 66 and PBZT/poly(trimethylhexamethylene terephthalmide) (PTMHT) molecular composites have been investigated using picosecond third‐harmonic generation at 1.9 &mgr;m. The measured &khgr;(3)(−3&ohgr;,&ohgr;,&ohgr;,&ohgr;) for the pure PBZT was (1.37±0.27)×10−11esu. The &khgr;(3)of PBZT/nylon composites showed a linear dependence on composition. In contrast, the &khgr;(3)of PBZT/PTMHT molecular composites significantly deviated from this linear dependence, showing enhanced values. No in‐plane anisotropy in any of the films was detected. The optical damage threshold of PBZT was measured to be ≳50 GW/cm2for 30 ps pulses at 1.9 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.104561

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A new laser structure suitable for optoelectronic integration is reported. It utilizes field effect at a heterointerface within the same structure used to build field‐effect transistors. A threshold current density of 560 A/cm2and a differential quantum efficiency of 56% were achieved.

ISSN:0003-6951    

DOI:10.1063/1.104562

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report for the first time high‐speed (Gbit s−1), single mode, digital (on‐off) modulation of intracavity loss modulated 1.55 &mgr;m InGaAs/InP multiple quantum well distributed feedback lasers. The lasing spectrum, observed to be asymmetrically broadened under high‐speed modulation, is shown to result from large carrier density variations which accompany this switching scheme. We also show, for the first time, digitally current‐modulated lasers have broader linewidths than devices which use intracavity loss modulation.

ISSN:0003-6951    

DOI:10.1063/1.104563

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report on the use of a Raman microprobe to investigate the nonlinear optical process of polarization rotation in Ti:LiNbO3optical channel waveguides. Selection rules allow the Raman scattered signal collected in a direction orthogonal to the plane of the waveguide to provide information regarding the polarization state of the light propagating in the waveguide. From this data a threshold value of power necessary to initiate the polarization rotation is obtained and used to calculate a value of &bgr;15, an asymmetric component of the photovoltaic tensor. The value of &bgr;15for an X‐cut, Y‐propagating channel waveguide was found to be 8×10−13A/W and that for a rapid thermally annealed Z‐cut, Y‐propagating sample 4×10−14A/W.

ISSN:0003-6951    

DOI:10.1063/1.104564

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

For the first time, the oscillation wavelength and the laser structure dependence of the K factor and of the nonlinear gain suppression coefficient &egr; in semiconductor lasers were systematically investigated. As a result, we suggest that the nonlinear gain effect can be explained by the spectral hole burning theory.

ISSN:0003-6951    

DOI:10.1063/1.104565

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A method for measuring theinsitupoling and relaxation of an electro‐optic polymer lightguide is presented. The poling/relaxation of a single film is compared with the behavior of the same film in the vicinity of a ferroelectric composite sublayer. The stability of the dye orientation obtained by poling is controlled by the ferroelectric substrate. Thus the stability of dye orientation in an electro‐optic polymer may be enhanced.

ISSN:0003-6951    

DOI:10.1063/1.104566

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A multiple quantum well GaAs/AlGaAs laser with two electrically isolated contacts is passively mode locked in an external cavity at the first through sixth harmonics of the pulse round‐trip frequency of 1.17 GHz to produce pulses shorter than 10 ps. The repetition rate is switched between harmonics by adjusting the gain section current, and large hysteresis between the different repetition rates is observed, with up to four different repetition rates for the same gain current. The results are compared with small and large signal passive mode‐locking theories by considering modifications to the saturated gain recovery between pulses when the laser operates at different harmonics.

ISSN:0003-6951    

DOI:10.1063/1.104567

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The nonlinear optical properties of a new class of strained‐layer superlattices (intrinsic Stark effect superlattices) have been investigated. Specifically, we have compared the nonlinear transmission of Ga1−xInxAs‐GaAs strained‐layer superlattices grown along the (211) axis to identical superlattices grown along the (100) axis, and found that the optical nonlinearity in the (211) sample is about one order of magnitude greater than in the (100) sample. A blue shift of the exciton resonance and an increase in the exciton absorption strength in the (211) sample with increasing light intensity was observed (attributed to screening of the intrinsic Stark effect fields by photogenerated carriers), resulting in the stronger optical nonlinearity. The maximum of the nonlinear absorption index, ‖&agr;2‖, in the (211) sample was 54 cm/W (‖Im &khgr;3‖=0.33 esu) whereas in the (100) sample the maximum of ‖&agr;2‖ was 6.9 cm/W (‖Im &khgr;3‖=0.042 esu). The measured carrier recovery time in both samples was 2 ns.

ISSN:0003-6951    

DOI:10.1063/1.104568

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Measurements of the optical power required to switch on‐and‐off an optical bistable diode laser amplifier as a function of detuning and current from threshold are presented. Good quantitative agreement between the theory for a nonlinear Fabry–Perot and the experimental results are obtained. A linewidth enhancement factor of 3.1 and a value for the change of the refractive index versus carrier density of −1.8×10−20cm3are extracted from the measurements.

ISSN:0003-6951    

DOI:10.1063/1.104569

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We demonstrate a new waveguide intensity modulator that uses the field‐dependent refractive index change associated with quantum wells to control the lateral confinement of light in a slab waveguide. By operating at photon energies ∼40 meV below the zero field electron–heavy hole transition energy, we show, conclusively, that the field‐induced refractive index change is primarily due to the quantum‐confined Stark effect. Intensity modulators are demonstrated withon/offratios better than 3:1. Devices based on this electrically controllable lateral confinement will play an important role in integrated optics.

ISSN:0003-6951    

DOI:10.1063/1.104545

出版商:AIP    

年代:1991

数据来源: AIP