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.<>     

Low-loss single-mode InP/InGaAsP waveguides grown by MOVPE

Losses as low as 0.4 ± 0.1 dB/cm for TE- and 0.65 ± 0.1 dB/ cm for TM-polarised light have been observed in tightly confined single-mode InP/lnGaAsP waveguides grown by MOVPE and processed using RIE. These are the lowest losses reported for InP-based waveguides. The structure could be used to make low-loss modulators for communications wavelengths.     

Extremely low loss InP/GaInAsP rib waveguides

The authors have fabricated InP/GaInAsP rib waveguides with losses as low as 0.18 dB/cm for the TE polarisation and 0.26 dB/cm for the TM polarisation. The length of the waveguides was 28 mm. These losses are measured with the Fabry-Perot method and repeated for different lengths of the waveguide for determining the reflection coefficient.<>     

Gigahertz-bandwidth InGaAsP/InP optical modulators/switches with double-hetero waveguides

A new kind of InGaAsP/InP electro-optic directional coupler modulator/switch with double-hetero plano-convex waveguides, which is suitable for monolithic integrated optics, has been proposed and demonstrated. The fabricated devices have shown low optical loss (4 dB/cm) and high modulation bandwidth of 1 GHz at 1.3 ?m wavelength.     

InP/InGaAsP脊波导的单模特性与偏振特性研究

以InP/InGaAsP脊形波导结构为研究对象,采用有限元算法(FEM),系统地仿真分析了在固定芯层厚度的情况下,不同脊高和脊宽条件下脊形波导的单模特性和偏振特性.在芯层厚度一定的情况下,脊宽越窄,刻蚀深度越浅,波导的传输模式越接近单模.在深刻蚀情况下,脊波导模双折射系数受到脊宽的影响较大,波导的偏振不敏感性较差;在浅刻蚀情况下,模双折射系数(△n=nTE-nTM)受到脊宽和脊高的影响较为微弱,稳定在1.2×10-3.相关仿真和分析为基于InP/InGaAsP脊波导的光电子器件的结构设计提供了一定的理论支持.     

Mode evolution type polarization splitter on InGaAsP/InP

A new type of mode-evolution polarization-splitter based on InGaAsP/lnP has been designed and realized. The component uses the large waveguide birefringence of the first-order TE and TM modes in a ridge waveguide made in a heterostructure, In the input section an asymmetric Y-junction acts as a mode converter in order to inject first-order TE- and TM-modes in a polarization-splitting section, which consists of a Y-junction formed by a bimodal and a monomodal waveguide. In the output section a third Y-junction is connected to the bimodal waveguide to couple the first-order mode to a monomodal output waveguide. Components that are 6-mm long and show polarization splitting at a wavelength of 1.55 μm have been realized. The best splitting ratios are close to -20 dB, which is in agreement with BPM simulations. Excess losses are below 1 dB     

Bragg gratings on InGaAsP/InP waveguides as polarizationindependent optical filters

The fabrication and operation of Bragg gratings for future wavelength-division multiplexing (WDM) devices in integrated optical circuits are discussed. Crosstalk attenuation of more than 20 dB with respect to the optical power and spectral bandwidths of up to 2.2 nm were achieved. Polarization-independent operation of the gratings, an important qualification for their operation in fiber optical transmission systems, was demonstrated with a filter bandwidth of 0.2 nm at -10 dB and channel spacings as small as 1 nm     

Numerical analysis of InP/InGaAsP ARROW waveguides using transfermatrix approach

The transfer matrix method is employed to analyze the modal propagation within planar InP/InGaAsP antiresonant reflecting optical waveguides (ARROW) at the operational wavelength of 1.55 μm. The numerical results provide an accurate picture of dispersion and attenuation of both TE and TM polarized waves. Spatial properties of the modes are also investigated and detailed plots of the variation of electric field amplitude with layer thickness are given     

Low-loss InGaAsP/InP submicron optical waveguides fabricated by ICP etching

The fabrication and characterisation of low-loss InGaAsP/InP optical submicron waveguides made with ICP etching is reported. Their width ranges from 0.2 to 2 /spl mu/m. For the 0.5 /spl mu/m width, the propagation losses at /spl lambda/=1.55 /spl mu/m as low as 4.2 dB/mm have been measured.     

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.<>     

Low-loss fiber-chip coupling by InGaAsP/InP thick waveguides forguided-wave photonic integrated circuits

A generic waveguiding structure is reported with low coupling loss (⩽1 dB/facet) with lensed fibers and low propagation loss (⩽1 dB/cm). This structure is suitable for low loss guided-wave photonic integrated circuits including active elements such as switches, and passive interconnections such as mirrors, and allows low polarization dependent operation. Which is required for instance in wavelength demultiplexers. This structure based on a single epitaxy is of interest for low cost photonic switching fabrics     

A comparison between finite element calculations and experimentalresults on InGaAsP/InP waveguides

Calculated and measured properties of InGaAsP/InP waveguides are compared. The spectral response of Bragg gratings was used to measure precisely the effective indexes of the guided modes of InGaAsP/InP waveguides. The shape of the near fields and the effective refractive indexes of waveguides, which support more than one guided mode, show an excellent agreement between theory and experiment. It is shown that rigorous calculation methods such as the finite-element method can be used to predict exactly the optical properties of integrated devices     

Investigation of Bragg gratings on planar InGaAsP/InP waveguides atnormal and oblique incidence

The polarization-dependent mode coupling of Bragg gratings on planar InGaAsP/InP waveguides is investigated by transmittance and reflectance measurements at normal and oblique incidence in the 1.5-μm wavelength region. Strong coupling between TE (transverse electric) and TM (transverse magnetic) modes is observed at oblique incident, whereas the TE-TE coupling vanishes at an incidence angle of 45°. The behavior of the near field close to the Bragg wavelength and the effects of radiation into the substrate are analyzed. It is experimentally shown that small deformations of the phase fronts on the input side lead to strong interference effects on the output side     

Etched-coupled-cavity InGaAsP/InP lasers

A new structure for coupled-cavity lasers operating at 1.25 ?m wavelength is presented. Using chemical etching, we made a three-cavity laser from an index-guided channelled-substrate Fabry-Perot laser. It oscillates in a single longitudinal mode with a side-mode suppression ratio of 200:1 in the pumping current range of 120 mA to 220 mA. The same mode was maintained at a fixed current of 160 mA as the heat-sink temperature was varied from 9°C to 45°C. The advantages of this laser over other coupled-cavity lasers are the simplicity of fabrication, the accuracy of cavity length control, and the possibility of incorporating short-etalon sections in the coupled cavities.     

InGaAsP/InP phototransistor-based detectors

Two kinds of phototransistors-a Schottky Collector Phototransistor (SCPT) and a Photo-Darlington Transistor (PDT), which should prove useful for switching and high current application, respectively-have been fabricated from InGaAsP/InP wafers grown by LPE. The SCPT exhibited gain greater than 100. The characteristics of the SCPT are compared with those of n-p-n phototransistors and are found to differ considerably. A PDT with a gain of 100 has been fabricated, and collector currents over 100 mA can be maintained without paying special attention to the heat sink. The details of the fabrication procedures and characteristics of these devices are described in this paper.     

Compensation of internal thermal stresses in InGaAsP/InP lasers for polarization stabilization

Internal thermal stresses in the active layer of a conventional InGaAsP/InP laser may cause polarization instabilities which normally do not exist in conventional AlGaAs/GaAs lasers. We analyze a structure with a buffer layer for Polarization stabilization by compensation of the internal thermal stresses in InGaAsP/InP lasers. Stress analyses are carried out for various structures to obtain the conditions for optimal stress-free structures. The effects of stresses from external sources are also discussed.     

InGaAsP/InP BH lasers on p-type InP substrates

A 1.55 ?m InGaAsP/InP BH laser is achieved on a p-type InP substrate resulting in a simple fabrication process. A threshold current as low as 40 mA under CW operation and a pulsed power rating of several hundred mW at 8 A peak current are achieved in buried-heterostructure lasers.     

High-speed InGaAsP/InP multiple-quantum-well laser

The authors describe practical high-speed InGaAsP/InP lasers based on compressively strained quantum wells. Buried heterostructure lasers with threshold currents of 10 mA and slope efficiencies of 0.23 mW/mA are used. A modulation bandwidth of 20 GHz is obtained at a low drive current of 90 mA. A K factor of 0.25 ns is obtained and the intrinsic bandwidth of these lasers is estimated at 35 GHz     

InGaAsP/InP Schottky collector phototransistor

The letter describes the first successful InGaAsP/InP transistor with an n-InP emitter, a p-In0.73Ga0.27As0.63P0.37 base and an Au Schottky collector. The device exhibited an optical gain in excess of 100 and an optical switching characteristic. The fabrication procedure is presented in the letter.     

InP/InGaAsP double-heterostructure optoelectronic switch

The double-heterostructure optoelectronic switch (DOES), fabricated in the InP/InGaAsP material system, is demonstrated. The functional characteristics and operational parameters exhibit a lower switching voltage (≈1.8 V) and a higher on-state holding current (≈20 mA) than found in either the Si/SiGe- or GaAs/AlGaAs-based DOES of comparable structures and doping levels. In the on-state, optical emission is observed in a manner analogous to a light emitting diode. However, enhanced optical emission is observed when the device is biased in the regime of negative differential resistance