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The continuous wave laser-induced damage thresholds of Schott chalcogenide glasses, IRG-24, IRG-25, and IRG-26, are measured for a 5s exposure of 1.07 μm light focused to a spot size with 1/e2 diameter of 830 μm, following the International Organization for Standardization standards.

Organometallic iridium(III) complexes have seen widespread use over the past two decades, particularly as phosphorescent dopants in organic light emitting diodes (OLEDs) due to their large spin-orbit coupling and metal-toligand charge transfer (MLCT) excited states. Interest in the non-linear optical (NLO) applications of these materials has increased recently with reports of both two-photon absorption (2PA) and reverse saturable absorption (RSA). A family of materials of the form [IrIII(NO2piq)2(acac)] were synthesized and characterized, where acac is acetylacetonate and NO2piq is a nitrophenylisoquinoline ligand. In order to assess structure-property relationships for the photophysics of these complexes, the placement of the nitro group was altered on the phenyl ring. Systematic control over the maxima of the absorption and photoluminescence bands attributed to the MLCT excited states was achieved through the ligand variation. The photophysical properties of this family of materials are discussed in detail and include their linear absorption spectra, photoluminescence measurements at 298 and 77K, excited state lifetimes, and CIE color chromaticity coordinates.

We utilize the conventional Z-scan technique to provide absolute measurements of third-order nonlinear refraction coefficients (n2) in the mid-wave infrared at 2 µm and 3.9 µm of common optical materials that have transparency windows spanning this regime. We study a variety of narrow band gap and wide band gap semiconductors, fluoride crystals (BaF2, CaF2, LiF, and MgF2) and optical glasses, and a series of chalcogenide glasses. The n2 is found to span on the order of ∼10−15 to ∼10−12 cm2/W for the semiconductors, ∼10−16 cm2/W for the fluoride crystals and glasses, and ∼10−14 to ∼10−13 cm2/W for the chalcogenides. The experimental results are compared to previous measurements of n2 conducted in the visible and near-infrared along with empirical and theoretical formulations.

A symmetric gain optoelectronic mixer based on an indium gallium arsenide (In0.53Ga0.47As)/indium phosphide (InP) symmetric heterojunction phototransistor structure is being investigated for chirped-AM laser detection and ranging (LADAR) systems operating in the “eye-safe” 1.55 μm wavelength range. Signal processing of a chirped-AM LADAR system is simplified if the photodetector in the receiver is used as an optoelectronic mixer (OEM). Adding gain to the OEM allows the following transimpedance amplifier’s gain to be reduced, increasing bandwidth and improving the system’s noise performance. A symmetric gain optoelectronic mixer based on a symmetric phototransistor structure using an indium gallium arsenide narrow bandgap base and indium phosphide emitter/collector layers is proposed. The devices are simulated with the Synopsis TCAD Sentaurus tools. The effects of base–emitter interface layers, base thickness and the doping densities of the base and emitters on the device performance are investigated. AC and DC simulation results are compared with a device model. Improved responsivity and lower dark current are predicted for the optimized InGaAs/InP device over previously reported devices with indium aluminum arsenide emitter/collector layers.

Ternaries and quaternaries of ZnCd(Mg)Se can be grown lattice-matched to InP substrates with band gaps spanning most of the visible range, having potential applications as visible light emitters. The quality of these materials is very sensitive to the surface preparation of InP substrates and the initiation of growth. In this paper, we report the details of the growth initiation of ZnCdSe epilayers on InP substrates. The composition of ternary alloy, and thus the lattice-mismatch to InP, was controlled by adjusting the Zn and Cd fluxes. A fast substrate deoxidation, followed by initial low-temperature growth results in two-dimensional growth and substantial improvements of ZnCdSe epilayers. These results along with observations on the use of InGaAs and InP buffer layers indicate that control of the interface chemistry is essential to obtain high-quality materials.

We report the molecular beam epitaxial (MBE) growth of lattice-matched Zn x Cd y Mg 1− x − y Se quaternaries on InP substrates having a wide range of band gaps. The composition and, thus, band gap and lattice constant, can be accurately controlled by adjusting the group II fluxes. By optimizing the growth condition and incorporating of a III–V buffer layer, we have grown very high-quality quaternary layers. Our best lattice-matched samples exhibit double crystal X-ray rocking curves with full-width-at-half-maximum (FWHM) about 460 arcsec and photoluminescence line widths about 60 meV at 77 K for a band gap of 2.8 eV. These materials can be used for the fabrication of lattice-matched semiconductor lasers that can emit throughout most of the visible range, from yellow to blue.

Optical modulators are a key element of optical data communication systems. All modulators demonstrated to date rely on the free-carrier plasma dispersion effect. This method absorbs light, which changes the material's index of refraction. This absorption requires carrier transport and, in present implementations, suffers from slow minority carrier diffusion. Reducing the active thickness over which the carriers must diffuse in an attempt to improve speed reduces the strength of the effect, trading efficiency for speed. Here we investigate an entirely new type of silicon electro-optic modulator that does not have any of these trade-offs. It utilizes the Kerr induced refractive index change in silicon nanocrystals, which has been reported to be large (5E-17cm2/W) [1]. The proposed microdisk resonator modulator is shown in Figure 1. An oxide layer (grey) separates the active device layers from the silicon Si substrate (green). Light enters the waveguide on the right and is alternately exchanged between the microdisk resonator and the output of the waveguide. Figure 1 shows an estimate of the expected refractive index change versus applied voltage. An index change of ∼2 × 10−4 is enough to modulate the light, corresponding to a voltage of only 0.5–1.5 V. Confinement of light in the waveguide and microdisk is accomplished via a slot waveguide design. Speeds of more than 100Gbit/s are possible with this design.

We have grown high quality lattice-matched ZnCdSe and ZnSeTe on InP. To optimize the interfaces, the initial growth temperature was lowered and an As flux was used during the thermal treatment of InP substrates prior to epitaxial growth. Under optimized condition, 2D nucleation was observed by reflection high energy electron diffraction (RHEED) throughout the entire growth. Photoluminescence (PL), photoreflectance (PR), transmission electron microscopy (TEM) were used to carry out the sample characterization. Low temperature PL spectra for ZnCdSe show a narrow excitonic emission. PR spectra from ZnCdSe samples also suggest very high quality layers. The ZnSeTe exhibits a strong defect level emission at energy close to band gap and very weak deep level emission. TEM study suggest that the interfaces are comparable to those obtained between ZnSe and GaAs. These results, combined with the new possibilities from these materials, make InP an attractive substrate for II-VI epitaxy.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this work, we study the growth parameters of ZnSe on GaAs by MOCVD and characterize the epilayers by various techniques. Epilayers were grown using diethylzinc (DEZn) and diethylselenide (DESe) as source materials. Growth studies were done at 400 degree(s)C under different growth conditions in an atmospheric pressure MOCVD reactor. Different DESe to DEZn ratios (from 0.5 to 5) were used to study the effects of VI/II ratio on ZnSe quality. The as-grown ZnSe epilayers were characterized by double crystal x-ray diffraction, transmission electron microscope (TEM), and scanning electron microscope. The results show excellent surface morphology and crystal quality of ZnSe. The best material was grown on undoped GaAs at the VI/II ratio near unity. The full-width-at-half-maximum of ZnSe (approximately 0.5 micrometers thick) x-ray peak as low as 90 arc seconds was achieved. To our knowledge, this is the narrowest peak among the reported results of ZnSe on GaAs. TEM results also show very low defect density. ZnSe epilayer with low stacking faults density (less than 105/cm2) and large spacing between misfit dislocations (approximately micrometers ) were grown on GaAs.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.