摘要:

Nanosecond transmission to total internal reflection switching has been demonstrated using a thin absorbing film of carbon microparticles suspended in ethanol. The switching results from laser‐induced cavitation and the large refractive index mismatch that occurs when the vapor bubble meets the surrounding glass substrate. This extraordinarily large refractive index change (≳0.3) causes the incident beam to be totally internally reflected at the glass‐vapor interface. Switching energies below 1 &mgr;J have been measured using a 5 ns doubled Nd:YAG laser (&lgr;=0.532 &mgr;m) pulse. We have investigated the effects that particle concentration, film thickness, and bias temperature have on switching performance.

ISSN:0003-6951    

DOI:10.1063/1.104924

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The linewidth enhancement factor &agr; as low as 0.54 in In0.2Ga0.8As/GaAs/AlGaAs strained single quantum well lasers emitting at 0.97 &mgr;m has been measured from spontaneous emission spectra below threshold. On reducing the current further, &agr; goes down to 0.34. These low values of &agr; have been attributed to strain in the In0.2Ga0.8As active layer.

ISSN:0003-6951    

DOI:10.1063/1.104925

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A new scheme of noise suppression in electro‐optic sampling system by the probe beam polarization modulation is proposed, its operation principle is analyzed, and the performance is demonstrated experimentally. The method has the advantages that narrow‐band detection can be used instead of modulating the device under test with doubled sensitivity compared with conventional methods.

ISSN:0003-6951    

DOI:10.1063/1.104926

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report on the generation of ultrashort light pulses from a Nd:YAG laser, passively mode locked by an intracavity frequency doubler in a nonlinear mirror arrangement. The pulse duration in the range of 20–25 ps is the shortest obtained so far from a Nd:YAG laser mode locked by this technique. In addition, the mode locking with frequency doubling crystal has provided in this experiment second‐harmonic radiation amounting up to 38% of the fundamental radiation output and single‐pass conversion efficiency of about 80%.

ISSN:0003-6951    

DOI:10.1063/1.104927

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We study the dynamics of an electrically pumpedp‐Ge laser with frequency fixed to 100 cm−1by a novel selective cavity. The growing laser power increases the pump current long before it reaches a saturating power level, an effect explained by photoionization. We further find that the laser pulse can be delayed or even quenched by injected off‐resonance far‐infrared radiation. This effect not only gives a gain coefficient of 0.01 cm−1and a saturation power of 400 W−which confirms the high‐power capability of the laser−but furthermore reveals a novel quasihomogeneous broadening of the gain spectrum caused by transit‐time effects of rapidly moving holes.

ISSN:0003-6951    

DOI:10.1063/1.105235

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Separate‐confinement heterostructure diode lasers containing a strained Al0.18In0.20Ga0.62As single quantum well active layer and Al0.25Ga0.75As confining layers have been fabricated from structures grown on GaAs substrates by low‐pressure organometallic vapor phase epitaxy. The emission wavelength of these devices is 814 nm. Threshold current density is as low as 103 A cm−2for cavity lengthL=1500 &mgr;m, and differential quantum efficiency as high as 90% forL=280 &mgr;m. The characteristic temperatureT0is 214 K between 10 and 40 °C, and 159 K between 40 and 80 °C. Preliminary tests of cw operation suggest that these lasers are more reliable than AlGaAs/AlGaAs lasers.

ISSN:0003-6951    

DOI:10.1063/1.104928

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report an electric field induced‐guide/antiguide optical intensity modulator which has a very wide optical bandwidth from 1 to 1.55 &mgr;m (ON/OFF ratio ≳ 13 dB from 1 to 1.55 &mgr;m for both TE and TM modes), which is the largest ever reported before for an intensity modulator. A TE mode ON/OFF ratio larger than 21 dB at 1.15 &mgr;m, and a propagation loss ∼1 dB at 1.3 &mgr;m has been measured. The electro‐optic effects, along with carrier effects have been exploited to increase the refractive index under the guide and adjacent antiguide electrodes by applying reverse biases to them.

ISSN:0003-6951    

DOI:10.1063/1.104929

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Polarization switching and hysteresis are observed in a semiconductor laser with a two‐armed polarization‐sensitive external cavity. An intracavity polarization‐dependent saturable absorber is placed asymmetrically in one of the two arms of the external cavity so that one polarization mode is saturated more strongly than the other. The observed phenomena can be explained by the complementary processes of competition in the gain region and the polarization‐dependent saturable loss in the external cavity. This mechanism is potentially useful as the basis of a two‐mode switchable and bistable diode laser for applications as high‐speed optical memories and logic gates.

ISSN:0003-6951    

DOI:10.1063/1.104930

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Laser cleaning with pulsed ultraviolet and infrared lasers is successfully employed to remove particulate contamination from silicon wafer surfaces and from delicate lithography membrane masks. Particulate material investigated include latex, alumina, silicon, and gold. Gold particles as small as 0.2 &mgr;m can be effectively removed. This new and highly efficient laser cleaning is achieved by choosing a pulsed laser with short pulse duration (without causing substrate damage), and a wavelength that is strongly absorbed by the surface; the removal efficiency is further enhanced by depositing a liquid film of thickness on the order of micron on the surface just before the pulsed laser irradiation.

ISSN:0003-6951    

DOI:10.1063/1.104931

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

This letter describes 1.48 &mgr;m multiple quantum well (MQW) lasers with strained GaInAsP quaternary wells entirely grown by metalorgainic vapor phase epitaxy. The GaInAsP quaternary layers with 1.5% biaxially compressed strain showed an excellent crystal quality and an abrupt interface within half‐monolayer fluctuations which was verified with photoluminescence spectroscopy. The maximum continuous wave output power of 140 mW was obtained at 20 °C with 1500‐&mgr;m‐long lasers whose facets were coated by anti‐ and high‐reflection films. The small internal loss of 12 cm−1and a high internal efficiency of 70% were obtained.

ISSN:0003-6951    

DOI:10.1063/1.104932

出版商:AIP    

年代:1991

数据来源: AIP