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Mode locking of individual spatial lateral array modes of gain-guided GaAs single-quantum-well laser array with an external mirror is observed. The single-lobe fundamental array mode and several higher order array modes were individually selected by adjusting the external mirror. The array modes were characterized by the far-field patterns of the laser array. The corresponding spectrum consists a number of narrow longitudinal modes indicating that a single array mode was selected. These array modes were mode locked using a combination of feedback from the external mirror and sinusoidal RF modulation. The far-field patterns remained spatially constant when the RF modulation was applied. Autocorrelation pulsewidth measurements showed that the pulses have a Gaussian shape. Pulses as short as 70 ps were obtained for the lowest order array mode, where all the laser emitters were in phase, and increase with increasing array mode order.

The characteristics of gain-guided GaAs single-quantum-well laser arrays, using proton bombardment to confine the current flow to 11 stripes on 9-/spl mu/m centers, are described. The longitudinal-mode spectrum, the spectrally resolved far-field, and the near-field of this laser array were studied experimentally up to three times threshold current. The laser arrays are found to emit at /spl sim/10 longitudinal modes corresponding to the Fabry-Perot modes of the laser. The longitudinal spectrum is current dependent. Near threshold current, the spectrum consists of a number of longitudinal modes where only the fundamental mode of the array laser. At larger current, each of the longitudinal modes is broadened and the spectrum of each longitudinal mode consists of many individual emission lines of the array modes. For each longitudinal mode, the lowest order array mode emits at the longest wavelength and the highest order array mode emits at the shortest wavelength. The wavelength separation between neighboring array modes increases with increasing mode order. Fourteen array modes are found to emit simultaneously at three times threshold current. The experimental results are in good agreement with direct array-mode analysis based on the finite-difference method.

A mode-locked Yb/sup 3+/ fiber laser operating at 980 nm is reported. Using a semiconductor saturable-absorber mirror in a laser incorporating a grating-pair dispersive delay line, we obtain reliable self-starting 1.6-ps pulse operation.

Purpose A novel disposable endovascular chemotherapy filter (CF) device was developed to remove excess doxorubicin (Dox) from the blood during intra-arterial chemotherapy delivery to prevent systemic toxicities. Previous proof-of-concept established the capacity of the filter to bind Dox in swine serum in vitro. In this study, CF navigation, deployment and in vivo Dox binding was evaluated in the porcine inferior vena cava (IVC). Materials and methods An 18 Fr CF device was constructed with an ion-exchange membrane attached to an expandable 28 mm diameter Nitinol frame. Under X-ray fluoroscopy and contrast venography, the CF was percutaneously introduced via the internal jugular vein and deployed in the porcine infrarenal IVC. 50 mg of Dox (2 mg/ml) was injected over 10 min in the IVC below the CF device. Venous catheters with tips proximal and distal to the CF device in the infrarenal IVC obtained pressures and blood samples for Dox concentrations over 90 min across the CF device membrane. Results The CF device was successfully introduced and deployed in the infrarenal IVC in vivo. Visualization under X-ray fluoroscopy verified the proper placement and mechanical expansion of the Nitinol framework. In a 90 min study, the device was biocompatible, not leading to hemodynamic disturbances: pressure measurements taken throughout the experiment yielded a max gradient of 17 mmHg across the CF membrane. Venography demonstrated non-flow-limiting thrombus associated with the CF device after 90 min of deployment (swine were not heparinized). Significant Dox binding was noted with an 85%, 74%, and 83% decrease in relative pre- versus post-filter Dox concentrations at times 3, 10, and 30 min, respectively after Dox injection. Conclusion: We developed a biocompatible CF device that can be safely introduced, deployed, and removed from the IVC in vivo. The CF device demonstrated significant Dox binding, and could serve as a platform technology in drug therapy to allow for higher regional doses of drug while limiting systemic toxicity. In future in vivo experiments, animals or the CF device itself may be heparinized in order to prevent thrombosis. When fully developed, indications for this device could include head and neck cancer, with the device deployed in the superior vena cava or internal jugular veins during selective IA chemotherapy. Disclosures A. Patel: 1; C; NIH-NCI. 4; C; ChemoFilter. A. Chin: 1; C; NIH-NCI. 4; C; ChemoFilter. J. Yang: None. B. Thorne: None. M. Saeed: None. M. Wilson: 1; C; NIH-NIBIB, NIH-NCI. 4; C; ChemoFilter. S. Hetts: 1; C; NIH-NIBIB, NIH-NCI, Siemens, Covidien. 2; C; Stryker, Penumbra, Silk Road Medical, Medina Medical. 4; C; ChemoFilter, Medina Medical, DriftCoast.

Misfit dislocations in planar, zinc-diffused In 0.53 Ga 0.47 As PIN photodiodes were analyzed using defect etching, cathode-luminescence, and electron-beam-induced current (EBIC). It was found that the misfit dislocations in wafers grown by liquid-phase epitaxy are present only in the InP buffer layer and they act as non-radiative recombination centers. These dislocations also affect the p-n junction since the misfit stress locally increases the diffusion depth by 80–400 A. EBIC examination of the photodiodes under reverse bias shows that the misfit dislocations do not cause localized breakdown of the p-n junction.

A brief review of the status of current understanding of as-grown InP crystals and InGaAsP materials, problems associated with thermal-induced decomposition of these materials and mechanisms of degradation of InGaAsP epilayers is presented.

High-radiance InGaAsP double heterostructure light-emitting diodes (LEDs) that are fast and reliable have been developed for 1.3-μm optical transmission applications. These devices are prepared by liquid phase epitaxy on InP substrates. Improved growth procedures result in large-area wafers (up to 5.4 cm2) with excellent uniformity and high device yields. Optical power of ∼120 μW can be launched into 0.29-NA, 62.5-μm core fiber. On the basis of accelerated reliability tests the median life of these InGaAsP LEDs is expected to exceed 4 × 106 h at 70° C and current densities up to 40 kA/cm2. The projected failure rate owing to output power degradation (−1 dB) is below 1 FIT. These devices are expected to be useful in lightwave systems operating at data rates ≲140 Mb/s.

With x‐ray diffraction techniques, it is possible to routinely measure lattice parameters to several parts in 104 for thin‐film samples. However, measurements of lattice parameter changes for quaternary device structures several microns in width are not usually feasible with x‐ray diffraction techniques. For this reason, transmission electron microscopy has been used to determine the position of higher‐order Laue zone lines within convergent‐beam electron diffraction patterns from thin foil cross sections of planar quaternary layers grown on InP substrates. A calibration curve has been generated which describes the position of higher‐order Laue zone lines as a function of the lattice parameter determined from x‐ray diffraction measurements. For the active quaternary region of an elecro‐optical device structure, it is shown that ths calibration procedure may be sensitive to a relative change in lattice parameter as small as ±2 parts in 104.

During vapor phase epitaxy, PH3 is generally used to preserve InP substrates. While PH3 is effective in reducing thermal decomposition, we find that excessive PH3 can produce morphological imperfections on the substrate surface. It is shown that in the temperature range of 675 to 700°C there is an optimum PH3 pressure under which the InP substrate surface morphology remains unchanged.

The formation of dark spot defects (DSDs) in InP InGaAsP aged light emitting diodes has been investigated by spatially resolved cathodoluminescence, transmission electron microscopy and Rutherford backscattering. It is shown that DSDs are caused by the migration of Au from the p-contact. This migration occurs during device processing and aging. As a consequence, Au-In intermetallics and inclusions associated with glide dislocations and multiple faults form, respectively, within the contact and p-InP confining layers. These features are responsible for dark spot contrast observed in electroluminescent images.

The fabrication and performance of a hybrid dual-wavelength light source consisting of InP channeled substrate-buried-heterostructure lasers emitting at 1.3 and 1.5 μm are reported. At 50 mA bias, launched powers averaging 4.3 mW at 1.3 μm and 2.1 mW at 1.5 μm into a 62.5 μm core, lensed, graded-index optical fiber are achieved with coupling efficiencies in excess of 31 and 33% for each wavelength, respectively. The output from this optical fiber is fed, via a biconic connector, to a 8 μm core, single mode fiber with maximum launched powers of 753 μW (1.3 μm) and 450 μW (1.5 μm) recorded.

In this paper, the formation of dark spot defects (DSD's) in InP/InGaAsP LED's is studied by cathodoluminescence (CL) imaging, electron-beam-induced-current (EBIC) imaging, Auger electron spectroscopy (AES), and energy dispersive X-ray spectroscopy (EDS). Defects resulting in DSD's are shown by CL and EBIC to be located in either the p-InGaAsP contact layer or the p-InP confining layer for short aging times. For longer aging times, these defects are also found in the InGaAsP active layer. The presence of gold was not detected at the DSD's using EDS. However, gold was found in the form of submicron size inclusions at the contact layer-confining layer interface of cylindrically-lapped wafers using AES and EDS. Our results strongly suggest that the migration of gold from the p-contact during device processing and aging results in the formation of DSD's in InP/InGaAsP LED's.

Liquid phase epitaxy (LPE) has been used to grow planar buried In 1- x Ga x As y P 1- y /InP double heterostructures. It is show n that poor wipe-off after melt-back and subsequent epitaxial growth over the mesa results in melt-carry-over on the surface and walls of the buried mesa. These indium rich inclusions are sources of defects which propagate through the burying layers. Significant improvement in wipe-off is achieved by etching the indium charges prior to use and by utilizing a multiple melt-back process before the epitaxial growth of burying layers.

With the aid of far infrared transmission measurements on thick samples of bismuth in the Faraday geometry we have identified both the spin and combination resonance of the holes.

Cathodoluminescence together with secondary electron imaging techniques are employed to correlate morphological and electronic properties of the (11 2 1) face of n-CdTe before and after photoetching. It is shown first that the quantum efficiency of the Cathodoluminescence increases considerably after photoetching. This increase is attributed to the selective removal of defects from the CdTe surface after photoetching. Furthermore no spatial correlation is found between the uniformly distributed etch pits (≈10 9 cm −2 ) and material defects, e.g. dislocations, inclusions. Consequently the unique morphology of photoetched CdTe surfaces must be attributed to yet another property of the semiconductor surface, e.g. the variations in dopant distribution close (10–100 A) to the semiconductor surface.

Convergent-beam electron diffraction (CBED), which is one of the techniques available on a modern transmission electron microscope (TEM), is sensitive to small localized lattice parameter changes and its application is therefore important in the characterization of sub-micron device structures. Unfortunately, dynamical diffraction effects prevent direct extraction of changes in the lattice parameter from CBED patterns which are obtained from high atomic number materials such as compound semiconductors. Therefore, in order to measure the relative lattice mismatch of a quaternary (InGaAsP) device structure grown on InP, we have opted to calibrate the relative position of CBED features with X-ray lattice parameter measurements which were obtained from planar quaternary layers grown on InP substrates. Three parameters from bright-field CBED patterns were measured as a function of the X-ray determined lattice mismatch in order to establish three separate calibration curves. CBED measurements taken from a device structure were found to produce similar values of lattice mismatch when interpreted using the calibration curves. The close correspondence of these three values of the lattice mismatch ((4.541 ± 2.119) × 10−4, (5.158 ± 2.881) × 10−1 and (4.819 ± 4.021) × 10−4), enhances the credibility of this approach for the characterization of sub-micron device structures.

A low luminescence efficiency ring, concentric with the circular electrical contact, has been observed on p-InP and p-InGaAsP (λ = 1.1 μm) epitaxial layers using cathodoluminescence imaging. This low efficiency region is found to be due to contact alloying. A mechanism based on the thermal migration of a defect in the strain field produced by the p-contact is proposed.

InGaAsP LED's emitting at 1.3 µm are attractive sources for long distance transmission systems. These devices have been shown to have excellent reliability at 8 kA/cm2. In order to launch more power into the optical fiber it is desirable to operate at the highest possible current densities consistent with system reliability requirements. In this work, the high temperature aging behavior of these LED's has been studied at current densities from 20 to 40 kA/2. Both the standard LED structure, where the small diameter p-contact is isolated with a dielectric layer, and a structure in which a Schottky barrier is used for isolation are examined. Dark spot defect (DSD) formation is greatly enhanced at these high current densities in devices with dielectric isolation, limiting MTTF at T_{J} = 70\degC to 2 \times 10^{5} h. In contrast, devices with Schottky-barrier isolation remain essentially free of DSD's and have MTTF > 10^{7} h at 70°C. These results suggest that stress from the dielectric layer promotes the growth of DSD's. Schottky-barrier devices in which the dielectric layer is eliminated are, thus, better suited for high current-density operation.

In the liquid phase epitaxy on indium phosphide, the substrate,just prior to the growth of the first epitaxial layer, is commonly etched back with an indium melt to remove any thermallydegraded surface and to ensure uniform and consistent wetting.This procedure, however, often produces defects which degrade both planar and buried heterostructure devices. For planar edgeemitters and lasers, the resulting rippled surface morphology degrades device performance by scattering light. For buried heterostructures, the meltback in the regrowth step leads to indium-rich inclusions. The effects of meltback on material quality are presented, and a new multiple meltback procedure which maintains flat surface morphology and eliminates inclusions is described.

With X-ray diffraction techniques, it is possible to routinely measure lattice parameters to several parts in 104 for macroscopic specimens. However, measurements of lattice parameter changes for quaternary (InGaAsP) device structures several microns in width are not usually feasible with X-ray diffraction techniques. Convergent Beam Electron Diffraction (CBED), which is one of the techniques available on a modern transmission electron microscope (TEM), may be sensitive to these small, localized lattice parameter changes. Unfortunately, dynamical diffraction effects prevent direct extraction of changes in the lattice parameter from CBED patterns which are obtained from high atomic number materials. For this reason, we have chosen to calibrate the relative position of CBED features with X-ray lattice parameter measurements which were obtained from planar quaternary layers grown on InP substrates. For the active quaternary region of an electro-optical device structure, it is shown that this approach may be sensitive to a relative change in the lattice parameter as small as ±2 parts in 104, which is the uncertainty in the X-ray calibration measurements.

A 1.3 μm InP/InGaAsP channelled-substrate buried-heterostructure laser is monolithically integrated with a monitoring photodetector. The lasers have threshold currents in the range of 25–30 mA and the photodetector provides ∼ 15 μA of photocurrent per milliwatt of laser power.

A new type of a simple gain-guided GaAlAs laser using a Schottky barrier restriction (SBR) technique is presented. Low current thresholds of ~2.2 kA/cm2, CW operation up to 70°C with a T0 = 160°, and a high coupling efficiency to multimode fibres are comparable to the high-quality lasers prepared with more traditional current restriction methods. This excellent performance has been achieved with extremely simple processing afforded by the SBR scheme. Although these SBR lasers have not yet been subjected to aging tests, GaAIAs LEDs fabricated in an identical fashion show excellent reliability.

Measurements of the specific contact resistance on epitaxially grown layers of p-In1−xGaxAsyP1−y as a function of composition demonstrate the resistance minimum of 7×10−6 Ωcm2 for In0.53Ga0.47As. Growth procedures for the preparation of InGaAsP/InP double-heterostructure LED wafers incorporating such a ternary InGaAs contact layer are described. This contacting technique allows fabrication of high-performance devices with reproducibly low series resistance.

Narrow-stripe, V-groove edge-emitting 1.3 μm LEDs are reported that couple -15.2 dBm of peak power into a single-mode fibre. Transmission at 180 Mbit/s over 35 km of single-mode fibre is described; this result corresponds to the highest bit rate-distance product (6.3 Gbit km/s) reported to date for an LED source. Accelerated aging results are presented.

The potential of InGaAsP light-emitting diodes (l.e.d.s) as light sources for quantitative absorption measurements in the 0.9–1.6 μm region is discussed. Since a variety of chemicals, including atmospheric water vapour and pollutants such as CO2 and NO2 have absorption bands in the spectral region spanned by InGaAsP l.e.d.s, this technique is useful in evaluating impurity content. Detection of the atmospheric water vapour band centred at 1.38 μm is demonstrated. The application of this technique for assessing the OH content of optical fibres is also discussed.