Abstract: A light-receiving element may easily detect the barycenter of a light intensity of light having a long-wavelength band in an optical communication. An InGaAs layer (i-type layer) and a p-type InP layer are stacked on an n-type InP substrate. Electrodes are formed on both sides of the top surface of the p-type layer, and an electrode is formed on the bottom surface of the n-type substrate. An incident light impinged upon the light-receiving element is photoelectricly-converged into a photocurrent, and the photocurrent flows in the p-type layer to the electrodes. As a result, a current is derived from each of the electrodes, the magnitude thereof being dependent on the distances from the light impinging position to respective electrodes. The barycenter of a light intensity may be calculated from the currents derived from the electrodes and a light intensity may be obtained from the summation of the currents.

Abstract: A light demultiplexer in which a signal and a noise in each channel may be distinctly separated is provided. The light demultiplexer comprises a light-receiving element array for receiving light beams demultiplexed every wavelength from a wavelength multiplexed light beam and arranged in a straight line. The light-receiving element array includes a plurality of light-receiving elements for monitoring signals, and a plurality of light-receiving elements for monitoring noises. The light-receiving elements for monitoring signals and the light-receiving elements for monitoring noise are alternately arrayed in a straight line the direction thereof is the same as that of the arrangement of the demultiplexed light beams.

Abstract: An edge-emitting thyristor having an improved external luminous efficiency and a self-scanning light-emitting device array comprising the edge-emitting thyristor are disclosed. To improve the external luminous efficiency of an edge-emitting light-emitting thyristor, a structure where the current injected from an electrode concentrates on and near the edge of the light-emitting thyristor is adopted.

Abstract: A light-receiving element may easily detect the barycenter of a light intensity of light having a long-wavelength band in an optical communication. An InGaAs layer (i-type layer) and a p-type InP layer are stacked on an n-type InP substrate. Electrodes are formed on both sides of the top surface of the p-type layer, and an electrode is formed on the bottom surface of the n-type substrate. An incident light impinged upon the light-receiving element is photoelectricly-converged into a photocurrent, and the photocurrent flows in the p-type layer to the electrodes. As a result, a current is derived from each of the electrodes, the magnitude thereof being dependent on the distances from the light impinging position to respective electrodes. The barycenter of a light intensity may be calculated from the currents derived from the electrodes and a light intensity may be obtained from the summation of the currents.

Abstract: A light-receiving element array is provided in which the degradation of characteristic thereof due to the crosstalk may be prevented. An n-InP layer, an i-InGaAs layer, and an n-InP layer are stacked on an n-InP substrate. Zn is diffused into the topmost n-InP layer to form a p-type diffused region, resulting in a pin-photodiode. A passivation layer is deposited on the structure to a thickness such that a nonreflective condition is satisfied. On the passivation film, a light-shielding film is provided so as to cover the area between light-receiving elements.

Abstract: An edge-emitting thyristor having an improved external luminous efficiency and a self-scanning light-emitting device array comprising the edge-emitting thyristor are disclosed. To improve the external luminous efficiency of an edge-emitting light-emitting thyristor, a structure where the current injected from an electrode concentrates on and near the edge of the light-emitting thyristor is adopted.

Abstract: A self-scanning light-emitting element array using an end face light-emitting thyristor having improved external emission efficiency is provided. To improve the external emission efficiency of the end face light-emitting thyristor, the present invention adopts such structure that the current injected from an anode is concentrated to near the end face of the light-emitting thyristor. A self-scanning light-emitting element array is implemented by using such end face light-emitting thyristor.

Abstract: In the light-receiving element array device according to the present invention, a light-receiving section can be arranged at a position close to an input optical fiber so that the light-receiving element array device can be used as an optical demultiplexer based on the Littrow arrangement. Further the present invention enables suppression of coma aberration and minimization of an optical demultiplexer by shortening a length of the optical system. To achieve the above-described object, a rectangular chip having a light-receiving section with a number of light-receiving elements arrayed in row thereon is sealed in a rectangular package having external leads and the bonding pads on the chip and the bonding terminals of the packages are connected with a bonding wire or the like.

Abstract: When a diffraction grating having a grating period of d and a diffraction order of m for an incident light having a wavelength interval &Dgr;&lgr;i between i'th and (i+1)'th channels is used, an optical path length between the diffraction grating and the photodetector is represented by L and a mean output angle is represented by &thgr;o, a pitch pi between the i'th and (i+1)'th photodetectors in the photodetector array satisfies the equation of pi=m&Dgr;&lgr;iL/d cos &thgr;o.

Abstract: A light-receiving element array is provided in which the degradation of characteristic thereof due to the crosstalk may be prevented. An n-InP layer, an i-InGaAs layer, and an n-InP layer are stacked on an n-InP substrate. Zn is diffused into the topmost n-InP layer to form a p-type diffused region, resulting in a pin-photodiode. A passivation layer is deposited on the structure to a thickness such that a nonreflective condition is satisfied. On the passivation film, a light-shielding film is provided so as to cover the area between light-receiving elements.

Abstract: A light-receiving element is provided, which may easily detect the barycenter of a light intensity of light having a long-wavelength band in an optical communication. An InGaAs layer (i-type layer) and a p-type InP layer are stacked on an n-type InP substrate. Electrodes are formed on both sides of the top surface of the p-type layer, and an electrode is formed on the bottom surface of the n-type substrate. An incident light impinged upon the light-receiving element is photoelectric-converged into a photocurrent, and the photocurrent flows in the p-type layer to the electrodes. As a result, a current is derived from each of the electrodes, the magnitude thereof being dependent on the distances from the light impinging position to respective electrodes. The barycenter of a light intensity may be calculated from the currents derived from the electrodes and a light intensity may be obtained from the summation of the currents.

Abstract: In a method for forming a planar microlens according to the present invention, a wet etching is conducted to a glass substrate for a stamper while it is covered with a mask. After the etching is conducted and the mask is removed a wet etching is conducted again to the glass substrate to form densely arranged concave portions thereon, and thereby a stamper is obtained. An uncured resin is applied on the forming surface of the stamper, a glass substrate for a planar microlens array (MLA) is pressed thereto, and thereby the uncured resin is formed. The uncured resin is cured by applying an ultraviolet irradiation thereto and the stamper is released therefrom. The resin layer is removed by a reactive ion etching and whereupon the substrate is etched in a form corresponding to the form of the resin layer and whereby an all-glass microlens of high precision is obtained.

Abstract: When a diffraction grating having a grating period of d and a diffraction order of m for an incident light having a wavelength interval &Dgr;&lgr;i between i'th and (i+1)'th channels is used, an optical path length between the diffraction grating and the photodetector is represented by L and a mean output angle is represented by &thgr;o, a pitch pi between the i'th and (i+1)'th photodetectors in the photodetector array satisfies the equation of pi=m&Dgr;iL /d cos &thgr;o.

Abstract: In a method for forming a planar microlens according to the present invention, a wet etching is conducted to a glass substrate for a stamper while it is covered with a mask. After the etching is conducted and the mask is removed a wet etching is conducted again to the glass substrate to form densely arranged concave portions thereon, and thereby a stamper is obtained. An uncured resin is applied on the forming surface of the stamper, a glass substrate for a planar microlens array (MLA) is pressed thereto, and thereby the uncured resin is formed. The uncured resin is cured by applying an ultraviolet irradiation thereto and the stamper is released therefrom. The resin layer is removed by a reactive ion etching and whereupon the substrate is etched in a form corresponding to the form of the resin layer, and whereby an all-glass microlens of high precision is obtained.

Abstract: The present invention concerns a method of preparing an alkali metal diffusion-preventive layer by applying one of three specific methods in a method of forming an alkali metal diffusion-preventive layer containing phosphorus at the inside of the substrate containing silicon by ion implantation of phosphorus, thereby enabling to prepare an alkali metal diffusion-preventive layer having higher alkali metal diffusion-preventive performance than that of the alkali metal diffusion-preventive layer prepared by the conventional method.