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.     

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.     

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.     

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.     

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 planar optical waveguides using matrix approach

We present here a simple matrix method for obtaining propagation characteristics, including losses for various modes of an arbitrarily graded planar waveguide structure which may have media of complex refractive indices. We show the applicability of the method for obtaining leakage losses and absorption losses, as well as for calculating beat length in directional couplers. The method involves straightforward 2 × 2 matrix multiplications, and does not require the solutions of any transcendental or differential equations.     

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.     

Facet oxidation of InGaAsP/InP and InGaAs/InP lasers

The facet oxidation of InGaAsP/InP and InGaAs/InP lasers is investigated after aging under high constant optical output power or high current stress. Facet oxidation in InGaAsP/InP lasers is negligibly small under several thousand hours of practical operation. The thickness of oxide film increases in proportion to optical output power and logarithm of aging time. The growth rate of facet oxide film weakly depends on the junction temperature and the activation energy is estimated to be 0.07 eV within a experimental range between 25 and 150°C. The facet of InGaAs/InP lasers are oxidized more easily than that of InGaAsP/InP lasers but are about two orders of magnitude more stable against oxidation than that of AlGaAs/GaAs lasers.     

InGaAsP/InP dual wavelength lasers

The first successful dual wavelength lasers emitting at 1.2 ?m and 1.3 ?m wavelengths are described. The lasers operated up to 0°C.     

InGaAsP/InP wavelength-selective heterojunction phototransistors

High-gain phototransistors with narrow spectral response (wavelength-selective phototransistors) have been developed by adding an absorption layer to a wide-bandgap heterojunction phototransistor using the InGaAsP/InP material system. The spectral response peaks at approximately 1.2 µm and the spectral half-width of 53 nm is achieved. This device exhibited an optical gain as high as 400 at the peak wavelength under an incident light power Pinof 3.6 µW. The rise time was measured to be 18 µs at Pin= 10 µW. The noise characteristic was also measured for this device, and the resultant detectivity D^*was estimated to be 3.7 × 10¹⁰cm . Hz^1/2/W at a frequency of 2 kHz under an optical bias level of 0.1 µW. These characteristics have been theoretically discussed in detail.     

Analysis of the propagation losses of InP/InGaAsP trench waveguides fabricated by focused ion beam

Focused ion beam was used to fabricate 2 mm-long, 4 μm-wide and 4 μm-deep multimode trench waveguides in InP/InGaAsP. An automated stitching method was developed to fabricate mm-long structures using alignment marks. The waveguides were sputtered or etched using I₂ at room temperature and 150 °C stage temperature. The propagation losses induced by the different fabrication techniques were measured and ranged between 50 and 82 dB/cm. A damaged layer with implanted Ga and the sidewall roughness are identified to be the most important causes for the losses. FIB is shown to be a single-step fabrication technique for rapid-prototyping of photonic structures in InP/InGaAsP.     

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     

InGaAsP／InP单片集成波长解复用器件

报道了基于二维凹面光栅的单片集成波长解复用器件，器件刻蚀在ＩｎＧａＡｓＰ／ＩｎＰ平板波导上，通过凹面光栅的色散作用实现不同波长光的分离，光的输入输出耦合由波阵列来完成，器件的工作波长在１．５μｍ附近，通道间隔约４．３ｎｍ。本文给出了器件的设计方法，制作工艺和初步测试结果。     

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.     

InGaAsP／InP系选择性刻蚀技术

比较了用于ＩｎＧａＡｓＰ／ＩｎＰ系的几种腐蚀液的选择性刻蚀效果并给出了最佳选择性刻蚀条件。