Passive optical GaInAsP/InP waveguides

We have fabricated GaInAsP/InP rib waveguides with lengths of up to 7 mm and widths between 2.5 and 10 ?m. The waveguides show low losses of ? = 1.38?1.84 cm?1 at a wavelength of 1.3 ?m.     

Extremely low threshold operation of 1.5 mu m GaInAsP/InP buried ridge stripe lasers

1.5 mu m Fabry-Perot lasers exhibiting extremely low threshold currents have been obtained with a buried ridge stripe (BRS) structure. Threshold currents are 5.7 and 15.5 mA for 300 mu m and 1 mm cavity lengths, respectively, in CW operation. The optical losses of the buried waveguide have been determined from the external quantum efficiency dependence with cavity length.<>     

GaInAsP/InP buried-heterostructure optical waveguides at a 1.5 μm wavelength

Buried-heterostructure GaInAsP/InP optical waveguides at a 1.5 ?m wavelength have been fabricated and a propagation loss of 2?2.5 cm?1 was obtained.     

First digital optical switch based on InP/GaInAsP double heterostructure waveguides

A Y-junction digital optical switch based on InP/GaInAsP has been realised and operated using either carrier injection or carrier depletion. the switch functions with both TE and TM polarised light. In the case of current injection, 30 mA is enough to obtain a crosstalk up to 20 dB for TM polarisation and 10 dB for TE polarisation.<>     

Extremely high power 1.48 μm GaInAsP/InP GRIN-SCH strained MQWlasers

A record CW output power of 360 mW at 25°C was achieved by investigating the structure of optical confinement layer in 1.48 μm GRIN-SCH MQW lasers. It is experimentally demonstrated that the use of a wide bandgap and thin SCH layer gives a high differential quantum efficiency without expense of threshold current. Low driving currents, 195 mA for 100 mW, 450 mA for 200 mW and 890 mA for 300 mW, were obtained in the optimized cavity lengths     

Low loss mirrors for InP/InGaAsP waveguides

The loss associated with a mirror in an InP-based waveguide has been investigated. Mirror roughness and non-verticality were both significant sources of loss. Mirrors with only 1 dB loss have been produced through novel fabrication techniques.<>     

An optimized InGaAsP/InP polarization converter employing asymmetric rib waveguides

In this paper, we report on the design of a compact (/spl ap/ 226 /spl mu/m) on-chip InGaAsP/InP polarization converter based on an asymmetric rib waveguide. Our theoretical analysis demonstrates that the device displays a conversion efficiency of < -25 dB (> 99.68% power conversion between orthogonal polarization) at 1550-nm wavelength with a nearly flat response over the optical C band. Regarding fabrication tolerances, we predict that the most sensitive design parameter is the waveguide width as the conversion efficiency drops to 10 dB for a deviation of /spl plusmn/ 0.1 /spl mu/m from the optimized value.     

Grafted GaAlAs rib waveguides on an InP substrate

Rib waveguides were fabricated on a 1.4 mu m thick GaAlAs epilayer granted on the surface of a semi-insulating InP substrate by epitaxial lift-off. Single-mode waveguides with propagation losses (<7 dB/cm) lower than heteroepitaxially grown counterparts have been achieved. TEM analysis on the GaAlAs/InP interface indicates surface scattering as one of the main loss mechanisms.<>     

Chemically etched-mirror GaInAsP/InP lasers--Review

Detailed results on stripe GaxIn1-xAsyP1-y/InP lasers (lambda = 1.3 mum) with chemically etched-mirrors are reviewed. These devices are fabricated from GaInAsP/InP wafers grown by liquid phase epitaxy. A simple stripe laser structure with one etched mirror and one cleaved mirror is proposed. Monolithic passivation has been achieved using a Si3N4film and metal coatings on the etched facets. These processes not only increase the reflectivity of the etched mirrors, resulting in threshold currents even lower than uncoated cleaved devices, but also ease the problem of bonding of the chips on heat sinks. CW operation at room temperature has been achieved. Threshold currents of devices with 10 μm stripe electrodes were about 180-200 mA. Short cavity lasers and integrated monitoring detectors have also been demonstrated.     

GaInAsP/InP unstable resonator lasers

Double-heterostructure GaInAsP/InP unstable resonator lasers have been fabricated for the first time. Both facets are made by a simple two-step chemical etching process. The required nearly vertical lateral curved cavity mirrors are achieved. The unstable resonator lasers exhibit an output power of 105 mW.     

GaInAsP/InP double-heterostructure planar LED's

GaxIn1-xASyP1-y/InP double-heterostructure wafers were grown on     

Low-threshold GaInAsP/InP mesa lasers

Threshold currents of double-heterostructure GaInAsP (1.38 ?m) stripe lasers are typically a factor of two higher than those of a similar GaAlAs structure. A significant reduction in the threshold current, down to 4?5 mA per micrometre of active layer width, is obtained in a simple mesa structure having reduced interface recombination at the edges of the stripe. At a current of 100 mA, output power exceeds 5 mW, and up to 2 mW is butt-coupled into a multimode graded-index fibre (50 ?m core, 0.23 NA).     

Very low threshold GaInAsP/InP double-heterostructure lasers grown by LP MOCVD

Room-temperature GaInAsP/InP DH lasers emitting at 1.3 ?m and having very low threshold current densities have been grown by LP MOCVD. Thresholds were lower than the best values reported for comparable devices grown by LPE, the lowest threshold being 430 A/cm2 for a cavity length of 950 ?m (width 150 ?m) with an active-layer thickness of d = 2200 A.     

Experimental determination of carrier-induced differential loss in 2-section GaInAsP/InP laser-waveguide

Measurements of threshold current density and external efficiency on broad-area laser-waveguide structure have led to the determination of the optical loss and differential loss d alpha /dN approximately=1.1-2.3 *10/sup -17/ cm/sup 2/ at lambda =1.53 mu m in a lambda /sub g/=1.30 mu m GaInAsP layer. This measurement will be useful for the design of tunable lasers.<>     

High-speed front-illuminated GaInAsP/InP pin photodiode

Describes a high-speed front-illuminated GaInAsP/InP pin photodiode for use at the optical wavelength of 1.3 μm. The device is grown on an n⁺-InP substrate and uses polyimide both as a passivation layer and as a bonding pad holder to reduce parasitic capacitance. An optoelectronic sampling measurement of the impulse response shows a pulsewidth (FWHM) of 28 ps. A 3 dB bandwidth in excess of 18 GHz has been achieved     

A monolithic GaInAsP/InP photovoltaic power converter

A monolithic GaInAsP/InP photovoltaic power converter (cell diam = 2.5 mm), optimized for power conversion at 1.06 µm, was successfuly fabricated by mesa isolation on semi-insulating InP substrates. An estimation of the quantum efficiency achievable with double heterostructures grown by liquid-phase epitaxy is given. Open-circuit voltages of 7.6 V, power-conversion efficiencies of 30 percent, and fill factors as high as 75 percent, were obtained from a device consisting of twelve cell segments connected in series.     

Be-implanted GaInAsP/InP double heterojunction laser diodes

Beryllium ion implantation has been used to fabricate broad-area GaInAsP/InP laser diodes operating at a wavelength of 1.3 μm, which have threshold current densities comparable to those obtained using conventional Zn doping during the epitaxial growth process. Both a Be-implant schedule which results in minimal diffusion of the implanted Be and one which results in significant diffusion have been investigated. On most wafers, the average normalized threshold current density (J_{nom} = J_{th}/d) using either implant schedule has been typically 6-8 kA/cm². μm. The lowest Jnomobserved was 4.2 kA/cm². μm and was measured on a "nondiffused" implanted laser.     

GaInAsP/InP DH laser on semi-insulating InP substrate with terrace structure

GaInAsP/InP DH lasers for the 1.3 ?m region were fabricated through a single LPE process on semi-insulating InP substrates with a terrace structure. The threshold current of the mounted lasers was typically 65 mA under CW operation at room temperature. Light output of 450 mW per facet was achieved at a pulsed injection current of 4.2 A.     

Scattering loss from rough sidewalls in semiconductor rib waveguides

A new scattering formula is applied to the slab loaded rib waveguide. Rib corrugations of up to 50 nm in amplitude lead to losses of the order of a few dB/cm, with trends which agree with experiment.<>     

GaAs/GaAlAs curved rib waveguides

Curved dielectric optical waveguides suffer from radiation loss due to bending. To minimize the bending loss and reduce the radius of curvature, it is necessary to fabricate guides which provide strong optical confinement. This paper gives a brief review of curved waveguide analysis and presents some experimentally measured loss values for GaAs/GaAlAs curved rib waveguides. The rib waveguides, fabricated using ion beam milling, have a large rib height and are tightly guided structures. When corrected for reflection losses and input coupling efficiency, a minimum loss of approximately 3 dB has been achieved for a multimode 90° curved guide with a radius of curvature of 300 μm, and 8.5 dB for a single-mode curved guide with a radius of curvature of 400 μm. It is believed that most of this residual loss is not radiation loss due to bending, but rather scattering loss due to rib wall imperfections.