Fabry-Perot and distributed feedback spot size converted 1.3 /spl mu/m lasers are demonstrated with competitive performance (/spl sim/10 mA threshold, >0.30 W/A slope) and narrow (16/spl times/9) far fields capable of coupling 45% of the output light into flat cleaved fiber. The Fabry-Perot device demonstrated error-floor-free transmission at 85/spl deg/C with a wide-open eye, uncooled 2.5 Gb/s operation up to 85/spl deg/C, and reliability of 105 FITS at 50/spl deg/C. The DFB devices have good DC performance with side mode suppression ratios of >40 dB. These devices will allow passive alignment and packaging without the need for intervening optics.

We describe the design, fabrication, and performance of a five-element quarterwave-shifted distributed feedback laser array with monolithically integrated spot size converters intended for use as a multiple-wavelength source in dense wavelength-division telecommunications systems. Facet power in excess of 10 mW with less than 150 mA bias and longitudinal side mode suppression greater than 40 dB were routinely achieved. Narrow far-field full-width at half-maximum angles of 6.9/spl deg//spl times/16.3/spl deg/ provided 3.5-dB coupling loss into single-mode fiber with 1.0-dB misalignment tolerances of /spl plusmn/2.0 /spl mu/m. With /spl plusmn/10/spl deg/C thermal tuning, 22 1555-nm channels spaced by 50 GHz were accessed with this device. Thorough field evaluation indicates that such a device is consistent with manufacturing requirements.

We have demonstrated a semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a novel dual-waveguide spot-size converter at the input for low-loss coupling to planar lightguide circuit silica waveguides or cleaved single-mode optical fiber. These devices exhibit greater than 10 dB fiber-to-fiber gain, output power of +4 dBm, 3-dB modulation bandwidth of 6 GHz, and modulator extinction ratios of 20 dB dc and 14.4 dB RF for a 2.4-V/sub pp/ drive.

We have performed numerical analysis of the electro- and photo luminescence (PL) of a wafer which would have been used in the manufacture of a multiquantum-well 1.5-mu m InGaAsP-InP-based semiconductor laser diode, It is shown that the deviation of the carrier distribution from a quasi-Boltzmann distribution plays a very important role in the interpretation of PL data. This is dramatically illustrated in the analysis of PL under short circuit conditions. Under this condition, the usual analytical theory predicts no FL, while our calculations agree with our experimental results in which FL is observed. For a wafer with electrical contacts, our calculations show that an increase in the positive applied voltage decreases the PL threshold and that the PL intensity saturates at large pump powers. Both these observations are consistent with the PL experiments. Moreover, our analysis shows that, in addition to the PL spreading effect, a nonBoltzmann carrier distribution is another important factor in determining the threshold of PL intensity.

Summary form only given. The guiding principles used in the design and fabrication of the Lucent Technologies electroabsorption (EA)-modulated device are discussed. They were designed to generate detailed understanding of modulator and laser quantum well design as they are linked through selective area growth (SAG) oxide pad geometry, and, using appropriate characterization techniques, ensure the equivalence of SAG and non-SAG crystal quality.

A computational model for selective area growth has been verified using a comprehensive suite of experimental measurements: atomic force microscopy, optical interference microscopy, microphotoluminescence, and micro-Xray diffraction. The model then allows for constructive engineering of the material thickness and composition through manipulation of the oxide mask used in selective area growth. This can be a fundamental input to the design of optical interconnects and integrated photonic devices.

The explosive growth in internet, multimedia and wireless traffic in recent years is rapidly exhausting capacity in public networks worldwide, forcing network service providers to aggressively install new lines and upgrade old ones. Fortunately, technological breakthroughs in the areas of erbium-doped fiber amplifiers (EDFA's), passive wavelength demultiplexers and low chirp sources have made all-optical dense wavelength-division multiplexed (WDM) systems a cost-effective way to utilize the vast bandwidth already available in the embedded fiber plant. WDM systems offer additional operational advantages, including high ultimate capacity, bit-rate transparency, flexible growth strategies, and the potential to use all-optical wavelength routing in future broadband network architectures, Commercial WDM systems operating at the OC-48 (2.5 Gbit/s) line rate are now available, and OC-192 (10 Gbit/s) terminal equipment which is under development will further enhance the capacity of these systems.One of the keys to viable WDM systems is the availability of inexpensive low-chirp optical transmitters. By taking advantage of photonic integrated circuit technology, it is possible to produce monolithically integrated DFB laser/EA modulators (EML's) with low chirp, low drive voltage and high extinction ratio, in a single compact package, In this talk we will discuss the operating characteristics of these devices and their relationship to WDM system performance.

Thresholdlike behavior of photoluminescence (PL) in heterostructure wafers is studied. It is shown that strictly speaking there is no PL threshold, and the thresholdlike dependence of PL on the pump power results from the combination of three factors: the PL spreading along the wafer surface, the change in the radiative fraction of electron-hole recombination, and the restricted aperture of the PL detector. The first two factors were found to be dominating in the wafers studied.

The features observed in luminescence and photoreflectance spectra are interpreted by detailed modeling of the electronic states, absorption and luminescence of the active region. The electronic states for the full active region (quantum wells together with separate confinement layers) are calculated using an eight band k (DOT) p model. The axial approximation, tested to be sufficiently accurate, is used to reduce the computational burden. The Poisson equation is included self consistently for the optically pumped case. Analysis of the photoreflectance spectra includes incorporation of an electric field across the active region. Good agreement for the positions of the features and their trends with compositional variables verifies the accuracy of the model. Higher lying transitions involve electron levels above the barrier energy which can be confined to the region of the wells by the self consistent field for pumped material.

As the p-type dopant most often used in metalorganic chemical vapor deposition (MOCVD) of Group III - Group V compound semiconductors, Zn presents problems in device design and performance because of its high diffusivity in these materials. While Zn diffusion into n-type layers such as InP:S has been observed frequently, there is little known as to the electronic and optical properties of the resultant material. We have grown InP samples by MOCVD which are doped with both Zn and S to levels as high as 3×1018 cm-3. These samples were analyzed by electrochemical C-V profiling, van der Pauw-Hall analysis, secondary ion mass spectroscopy (SIMS), and low temperature (10K) photoluminescence spectroscopy (PL). We have determined that good hole mobility is maintained in InP:Zn samples that are simultaneously doped with S up to a level of 4×1017 cm-3. PL analysis of co-doped samples shows peaks between 0.91 and 0.92 µm which are indicative of donor-acceptor transitions, and broad peaks with energy levels of approximately 1.0 µm which may be indicative of ZnS complexes or precipitates. SIMS analysis of Zn diffusion into Fe doped substrates shows that Zn diffusion is reduced in the presence of S in the lattice.

The first monolithically integrated DFB laser/Mach-Zehnder interferometric modulator fabricated by the selective area low pressure MOVPE growth technique is reported. A near 3-dB power divider at the Y-branches of the interferometer has been reproducibly achieved by a photolithographically defined dielectric mask used in the selective area growth technology and confirmed by an infrared near field imaging technique. A modulation depth of over 12 dB was achieved both in the forward and reverse bias to the arms of the phase modulator.< >

We have demonstrated the first monolithic integration of a DFB laser with a Mach-Zehnder type modulator fabricated by the selective area MOVPE growth technique and operating at 1.55 μm. A spatially resolved micro photoluminescence setup was used to characterize the crystal quality. We have achieved a low loss and near 3 dB Y-branch power divider in the structure with the modulator achieving an attenuation up to 17 dB and a π phase shift voltage of 2 V

Heterostructures of InGaAs/InP and InGaAs/InGaAsP were grown by low pressure metalorganic chemical vapor deposition (LP-MOCVD) in an EMCORE GS3200 system. Highly abrupt interfaces were attained with PL line widths for the InGaAs/InP system comparable to the best values reported in the literature for any crystal growth technique, MOCVD, MBE or CBE. These structures were characterized with low temperature (10K) photoluminescence (PL), transmission electron microscopy (TEM) and high resolution X-ray diffraction (HRXD).

The physics underlying normal incidence hole intersubband absorption in p-type semiconductor quantum wells is briefly reviewed. The fabrication and performance characteristics of a pseudomorphic Ge0.25Si0.75/Si p-type quantum well infrared photodetector on (001)Si are described. These devices show broadband response (8-14 mum) which is attributed to strain and quantum confinement induced mixing of heavy, light and split-off hole bands. Typical responsivity at lambda = 10.8 mum is 0.04 A/W over the 20-77 K temperature range. A detectivity D(lambda)* = 3.3 x 10(9) cm square-root Hz Watt-1, was measured at bias voltage of -2.4 V, for a temperature of 77 K, lambda = 10.8 mum and no cold-shield (i.e. T(cavity) = 300 K and an angular field of view theta = 180-degrees). Room temperature FTIR absorption measurements yield a peak absorption coefficient alpha(p) = 3914 cm-1 at lambda(p) = 8 mum, corresponding to a quantum efficiency eta = 3.1% at 300 K.

Normal incidence spectral response and bias dependent responsivity measurements on p-type GexSi1-x/Si quantum well infrared photodetectors reveal anomalous long wavelength photoresponse, extending out to 18 micrometers depending on quantum well parameters. Room temperature FTIR absorptance measurements do not reveal significant absorption in this wavelength range; aside from the shorter wavelength intersubband optical transitions near 6 - 12 micrometers in these Ge0.25Si0.75 quantum wells. Dark current induced filling of the higher-lying split-off hole state, with subsequent optical absorption, would give rise to infrared absorption in the 14 - 18 micrometers range; however the split-off ground state to heavy-hole ground state lifetime required is -10 microsecond(s) ecs. In two-hole state structures having 300 angstroms barriers we observe dramatic increases in responsivity for bias voltage above 3 V, attributed to hot-hole transport enhancement of the photoconductive gain. This behavior is not observed in 500 angstroms barrier width structures.

Photoluminescence from optically pumped strained-layer quantum wells of In0.17Ga0.83As/Al0.32Ga0.68As has been observed under hydrostatic pressures up to 100 kbars, using a diamond-anvil cell. High-resolution x-ray diffraction has been used to determine structural parameters. Analytic expressions have been derived for the hydrostatic-pressure dependence of the GAMMA-band-gap photoluminescence intensity for the case of a heterojunction. This allows us to differentiate between two possibilities: whether an observed pressure-induced GAMMA-X crossing in a quantum-well structure is indicative of a GAMMA and X crossing in the well material only, or whether the GAMMA-band edge in the well material crosses the X band edge of the barrier material. Only in the latter case can information on band alignments be obtained. The present heterostructure is found to satisfy the latter criterion, thus allowing the determination of DELTA-E-upsilon almost-equal-to (0.157 +/- 0.025) eV, at ambient pressure.