Showing papers by "Amnon Yariv published in 1975"

Process for fabricating small geometry semiconductive devices including integrated components

Abstract: Disclosed is a process for fabricating small geometry electronic devices, including a variety of integrated optical devices. The process includes the steps of holographically exposing a resist masking layer to a plurality of optical interference patterns in order to develop a masking pattern on the surface of a semiconductive body. Thereafter, regions of the body exposed by openings in the masking pattern are ion beam machined to thereby establish very small dimension undulations in these regions. These closely spaced undulations have a variety of uses in optical devices as will be described. The present invention is not limited to the geometry control of semiconductive structures, and may also be used in the geometry control of metallization patterns which have a variety of applications, or the geometry control of any ion beam sensitive material.

cw operation of distributed‐feedback GaAs‐GaAlAs diode lasers at temperatures up to 300 K

Abstract: Distributed‐feedback GaAs‐GaAlAs diode lasers with separate optical and carrier confinement have been successfully operated under dc bias up to room temperature. They lased in a single longitudinal mode with a threshold current density of 0.94 kA/cm2 at 170 K and 3.5 kA/cm2 at 300 K.

GaAs‐GaAlAs distributed‐feedback diode lasers with separate optical and carrier confinement

Abstract: Remarkable reduction of the threshold current density is achieved in GaAs‐GaAlAs distributed‐feedback diode lasers by adopting a separate‐confinement heterostructure. The diodes are lased successfully at temperatures up to 340 °K under pulsed operation. The lowest threshold current density is 3 kA/cm2 at 300 °K.

GaAs GaAlAs double-heterostructure injection lasers with distributed feedback

Abstract: GaAs-GaAlAs double-heterostructure distributed-feedback injection lasers are investigated at temperatures between 80 and 150 K under pulsed operation. The optical feedback for laser oscillation is provided by a corrugated interface between the p-GaAs active layer and the p-GaAlAs layer. The corrugation is made by two methods, ion milling and chemical etching, and the latter method is found to give the lower threshold. The laser oscillation occurs in a single longitudinal mode, whose wavelength is stable against the change of the excitation level. The temperature dependence of the wavelength of the distributed-feedback laser is shown to be 0.5 A/°, which is about \frac{1}{3} to \frac{1}{4} that of the conventional Fabry-Perot (FP) laser.

Embedded heterostructure epitaxy: A technique for two‐dimensional thin‐film definition

Abstract: Selective multilayer epitaxial growth of GaAs-Ga1–xAlxAs through stripe openings in Al2O3 mask is reported. The technique results in prismatic layers of GaAs and Ga1–xAlxAs "embedded" in each other and leads to controllable uniform structures terminated by crystal faces. The crystal habit (shape) has features which are favorable for fabrication of cw injection lasers, laser arrays, and integrated optics components which require planar definition.

Equivalence of the coupled‐mode and Floquet‐Bloch formalisms in periodic optical waveguides

Abstract: A comparison of two theories used to analyze distributed feedback lasers and periodic optical devices finds them, contrary to some claims, to be formally equivalent.

Integrated Optics: a Report on the 2nd OSA Topical Meeting.

Abstract: This report surveys the papers presented at the 2nd OSA Topical Meeting on Integrated Optics, which was held 21–24 January 1974 in New Orleans, La.

Intraband radiative transitions and plasma–electromagnetic‐wave coupling in periodic semiconductor structure

Abstract: Intraband radiative transitions can occur in a semiconductor with an artificial periodic structure (superlattice). The ’’lattice momentum’’ of the periodic structure makes possible the conservation of momentum during the electronic transition. When the electrons in the band are drifting in an electric field, an intraband population inversion may occur, providing optical wave amplification. Under conditions where the Landau damping of the semiconductor carrier’s plasma wave is low, phase‐matched coupling may occur between the plasma wave and a Floquet component of the electromagnetic wave and result in a high rate of power transfer from one of the waves to the other. These effects are discussed and analyzed quantum mechanically and suggestions are made with regard to possible device applications (amplifier, modulator) in the infrared regime.

X-ray laser with a single crystal waveguide structure

Abstract: An X-ray laser comprises a single crystal in the form of a thin film with an oriented set of prominent atomic planes so that when the crystal is pumped, X-ray photons which are emitted from one of the atomic constituents of the crystal, experience internal feedback (Bragg scattering) from the atomic planes thereby eliminating the need for external feedback. In addition the crystal functions as a thin planar waveguide confining the X-ray waves therein, thereby reducing the necessary pumping power and increasing overall efficiency.

Corrugated laser structures

Abstract: GaAs–GaAlAs double-heterostructure injection lasers consist of several epilayers of GaAs and GaAlAs grown on a GaAs substrate. The need for cleaved end mirrors may be eliminated in these lasers by incorporating internal periodic corrugation which provide feedback. This distributed feedback relies on Bragg reflection from the periodic perturbation, and thus the lasing wavelength is directly proportional to the corrugation period. Such corrugated laser structures are compatible with the fabrication of monolithic optical circuits and seem to be most suitable as light sources for integrated optics. Our group prepared corrugated structures by ion milling or chemical etching through a photoresist mask which was generated by the interference of two laser beams. We observed laser emission from GaAs–GaAlAs double heterostructures with internal corrugation when pumped electrically at 77 °K. Theoretical considerations indicate that such lasers should have a very low threshold current and a good wavelength selectivity. Further experimental work on these devices is now in progress.

Operating injection lasers by fast square current pulses of variable amplitude

Abstract: A simple solid state circuit was used to drive GaAs injection lasers by fast (∼100 nsec) square pulses of variable amplitude (0–25 A). The amplitudes of the current pulses and the corresponding emitted light pulses were measured by a dual peak detector circuit. Using these circuits we were able to plot automatically the current vs light curve and determine the threshold current of the laser diodes.

Fast, high‐current, high‐repetition‐rate pulse generator for injection lasers

Abstract: The circuit described is capable of generating high‐current (2–50 A), fast‐rise‐time (10 nsec), square‐wave pulses into a 50‐Ω load. This circuit may be used for driving injection lasers at high repetition rates (up to 1.5 kHz) when connected to coaxial cables.