Waveguide Diode Research Articles

AlInGaAs/AlGaAs strained quantum-well ridge waveguide lasers grown by metalorganic chemical vapor deposition

AlInGaAs/AlGaAs strained quantum-well ridge waveguide diode lasers with an emission wavelength of 890 nm are presented. These devices exhibit both single spatial and longitudinal mode operation up to 30 mW of optical output power. A CW threshold current of 13 mA was obtained for a 5- mu m-wide ridge waveguide having a cavity length of 500 mu m. The differential quantum efficiency was 52%. The lateral and perpendicular far-field radiation patterns (FWHM) from the laser were 6 degrees and 51 degrees , respectively. Reliability testing on uncoated gain-guided lasers made from the same wafer showed no sudden death failures and degradation rates as low as 4.6%/kh.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Gain saturation in traveling-wave ridge waveguide semiconductor laser amplifiers

The saturation behavior of traveling-wave ridge waveguide diode amplifiers is studied both numerically and analytically. It is shown that an 'effective saturation power' can be used to characterize the saturation of these devices by up to 4 dB. The effective saturation power, which is sensitive to device geometry, carrier density, and operating wavelength, is useful in the design of the ridge waveguide optical amplifiers. >

Modal reflectivity of uptapered, tilted-facet, and antireflection-coated diode-laser amplifiers

A numerical analysis of the modal reflectivity of tilted-facet laser-diode amplifiers is presented. It is shown that, with slightly angled facets, a large reduction of the reflectivity in a monomode diode should be achievable for TE and TM modes simultaneously either by applying a single-layer antireflection coating and optimizing the thickness and the width of the diode waveguide or by adiabatically uptapering the waveguide ends. A further significant reduction can be obtained by combining an antireflection coating with an uptapered waveguide. The characteristics of the dependence of the reflectivity on tilt angle and waveguide width and thickness are explained in terms of spectral overlaps between incident and reflected modes. The characteristic minima of the reflectivity are attributed to the oscillatory behavior of the spectra.

Electro- and Photoluminescence from Ultrathin SImGEn Superlattices

ABSTRACTP-i-n doped short-period SimGen strained layer superlattices (SLS) are grown on (100) silicon substrates by low temperature molecular beam epitaxy (300C°&lt;∼Tg&lt;∼400C°). The SLS's are grown with period lengths around 10 monolayers (ML) to a thickness of 250nm on a rather thin (50nm) homogeneous Si1−ybGeyb alloy buffer layer serving as strain symmetrizing substrate. Photoluminescence at T=5K is observed for various SimGen SLS samples, the strongest signal was found for a Si5 Ge5 SLS. Samples with identical SLS's but different buffer layer composition and thicknesses are grown to study the influence of strain on the PL. Electroluminescence (EL) at the same energy range is observed from mounted SimGen SLS mesa and waveguide diodes up to T=130K – for the first time reported in strain symmetrized short-period SimGen SLS. The intensity and peak positon of the EL signal was found to be dependent on the injected electrical power.

Modal analysis of radial-resonator waveguide diode mounts

A method of calculating the driving-point and transfer admittances of waveguide diode mounts with radial resonators is presented. The method is applicable to a variety of mount configurations, including the widely used resonant-cap mount. The analysis uses multimodal admittance matrices to represent the radial regions and their coupling and includes the influence of the waveguide boundary conditions. The analysis proceeds by first determining (from the matching of tangential fields at the common boundary) the coupling between radial regions in the form of a mode-coupling matrix. By multiplying this matrix with the generalized admittance matrices of connecting radial regions to form an overall admittance matrix, the driving-point and transfer admittances for a general radial-resonator mount can be extracted. The method is demonstrated by application to the resonant-cap mount. The accuracy of the analysis is confirmed by comparison with experimental results. >

Extension to third-order Coriolis terms of the analysis of ν10, ν7, and ν4 levels of ethylene on the basis of Fourier transform and diode laser spectra

The ν7, ν10, and ν4 levels of ethylene have been studied based on waveguide laser, Fourier transform, and diode laser spectra in the range from 798 to 1091 cm−1. The absolute calibration of these spectra is better than 0.0002 cm−1. To deal with so many and so accurate experimental data, we have developed in our analysis programs the Watson Hamiltonian up to the sextic centrifugal distortion coefficients and the interaction Hamiltonian up to the third-order Coriolis resonance terms. The molecular parameters of the vibrational ground state have been significantly improved on the basis of more than 4000 GSCD. In the analysis of ν7, ν10, and ν4 levels, we had to introduce the ν12 level, which contributes to the indirect coupling of ν7 and ν4 through strong Coriolis interactions. We obtain a statistical agreement with all experimental data with an estimated standard deviation equal to 0.84. The intrinsic intensity of the ν10 band has been determined to be 16 500 ± 2500 times lower than the intensity of the ν7 band.

Electromagnetic model of a radial-resonator waveguide diode mount

An electromagnetic model of a class of waveguide diode mounts that incorporates a radial resonator with the diode arbitrarily positioned is derived. The model is tested through comparison of numerical and experimental results for the input impedance of the mount. The tests show good agreement between theory and experiment and indicate that the model may be especially useful in investigating the effects of an off-centered positioning of the diode. >

Quasi-optical components at submillimeter wavelengths

Introduction With the increasing use of low noise heterodyne receivers at wavelengths shorter than ] ~a [|] and the need to match such receivers to telescopes [2], quasi-optical components are becoming increasingly important at these wavelengths. In this paper we will report upon the measurement of such components (horns, lenses and diplexers) at a wavelength of 650 nm (frequency = 460 GHz). Figure I shows a schematic of the MaxvPlanck-Institut fflr Radioastronomie 650 ~m Schottky barrier diode waveguide mixer-receiver. It has a system noise temperature of 870 K double sideband and a mixer conversion loss of 8.] dB [I]. In order to minimise signal losses the losses of the components preceding the mixer must be kept as low as possible; in addition the final beam should match that of the telescope, to obtain highest aperture efficiencies and lowest spill-over losses. In the following sections we report on the individual components and their performance at ~ = 6~O~m.

Longitudinal mode spectra of diode lasers

A theory is presented which explains the longitudinal mode spectra of diode lasers. The theory is based on spontaneous emission coupling into the longitudinal modes and the excellent agreement with experimental data for both gain guided and real refractive index waveguide diode lasers is obtained because of the more accurate and detailed modeling of the spontaneous emission coupling and the laser itself.

Subharmonically Pumped Millimeter-Wave Mixers

The two-diode subharmonically pumped stripline mixer has a pair of diodes shunt mounted with opposite polarities in a stripline circuit between the signal and local oscillator inputs. The circuit has low noise and conversion loss and substantial AM local oscillator noise cancellation.The local oscillator frequency is about half the signal frequency. A novel diode chip, the notch-front diode, which has ohmic contacts on the chip faces adjacent the face containing the diode junctions, was developed for these circuits. The notch-front diode permits the low parasitic reactance of the waveguide diode mount to be achieved in stripline circuits. The best performance for a two-diode subharmonically pumped mixer with notch-front diodes was a 400 K mixer noise temperature, obtained at 98 GHz which is comparable to the best fundamental mixers in this frequency range. The performance over a 47-110-GHz frequency range for this circuit with commercial beam-lead diodes is also presented.

Discussion of a 2-Gap Waveguide Mount (Short Papers)

An equivalent circuit is presented for a commonly used waveguide diode mount, providing the means for accurate theoretical analysis and design of components previously considered possible only by empirical means. Several applications are discussed and experimental confirmation is included for a variety of circuit configurations.

The Excitation of Planar Dielectric Waveguides at p-n Junctions, I

The fields excited within a planar dielectric waveguide by an externally incident electromagnetic field are studied in this paper. The dielectric waveguide fills the half space z > 0, while the half space z < 0 is air. The waveguide is formed by a nonuniform, anisotropic, nonabsorbing, dielectric medium. Different choices of the dielectric tensor for this medium yield different waveguides. Certain models which are particularly relevant to electro-optic diode waveguides and laser diode amplifiers are studied in some detail. An arbitary incident field will, in general, excite not only a finite number of propagating modes, but also a background of continuum modes. Integral representations of the total transmitted field within the waveguide as well as of the reflected field are obtained. The representation of the total transmitted field can be decomposed into a finite sum of discrete propagating modes, a continuum propagating field, and an evanescent field. Explicit evaluation of the fields depends on the solution of a pair of integral equations. In practice, the dielectric tensor of the waveguide differs but little from the dielectric constant of the surrounding material. An approximate solution is found for this case, and numerical results will appear in a following paper.

The Packaged and Mounted Diode as a Microwave Circuit

Suitable definitions of the elements in the equivalent circuit of a packaged diode yield a lumped-element circuit with an impedance at its terminals which is the same as the total radial-line impedance of the packaged diode with the outer surface of the diode taken as the terminal surface. Consideration of the packaged diode as a radial-line structure permits an analytical justification for the incorporation of the diode circuit with the circuits of waveguide, coaxial-line, and strip-line diode mounts. As a result, the lumped-element equivalent circuit of a packaged diode can be directly related to the microwave equivalent circuit of the diode and the mount together. Diode element values, which were obtained from low-frequency measurements, have been used in conjunction with the theoretically determined circuits of mounted diodes to predict resonant frequencies at X-band of waveguide, coaxial-line, and stripline mounts holding packaged diodes. Similarly, antiresonant frequencies of greater than 20 Gc/s have been predicted for diodes in a radial cavity. The validity of all these predictions has been verified by measurement.