Nec Corporation

Hiroshi Honmou

Masataka Itoh

Junichi Sasaki

Isao Yoneda

Kazuhiko Kurata

Toshitaka Torikai

Kiyoshi Fukushima

Yoshinobu Kaneyama

Jun-ichi Sasaki

An electrode of a laser diode (LD) is joined with a Si substrate via a solder layer. A cavity region is formed directly under the LD in the solder layer. The solder layer spreads outside the cavity region. Since there arises no stress in a space of the cavity region, the internal stress of the active layer, which is formed directly over the cavity region, is relaxed as compared with that in a conventional optical module, which is provided with no cavity region in the solder layer. Accordingly, a highly reliable optical module can be obtained.

Optical module

A low-cost optical coupling circuit that enables high-efficiency coupling between an optical transmission line 4 and a photodetector element 2 is provided with an optical transmission line 4 and a photodetector element 2, both located on a substrate 1. The substrate 1 propagates light and receives emitted light L2 from the optical transmission line 4. A filler material 8 having a refractive index that is either equivalent to or lower than the refractive index of the core of the optical transmission line 4 fills the space between the optical transmission line 4 and photodetector element 2.

Optical coupling circuit

It is an object of the invention to provide a optical semiconductor module, which is resisting against external noise and can be easily fabricated. The optical semiconductor module comprises an optical wave-guiding medium allocated on a substrate, a photosensor for optical to electrical converting the optical signal emitted from an output end of the optical wave-guiding medium, means for optically coupling the output end of the optical wave-guiding medium with a light-receiving surface of the photosensor, insulating resin for filling space surrounding an output part of the optical wave-guiding medium and the photosensor, and conductive resin, which is applied to the insulating resin and communicates with a ground plane connected with a ground terminal of the photo sensor. Insulting resin is composed of the first resin, which has a refractive index being the same as that of core of the optical wave-guiding medium, and fills a space between the output end of the wave-guiding medium and the light receiving surface of the photosensor, and the second resign, which is sealing resin for enclosing the first resin. Means for optically coupling is constituted of a mirror, which directs a light emitted from the optical wave-guiding medium to the photosensor.

Optical semiconductor module and method for manufacturing same

A light receiving element is comprised of a light sensitive surface on a semiconductor substrate and a positive electrode (anode), a negative electrode (cathode), a mounting precision test mask, a conductive electrode wire, and solder resist on the same substrate surface. A metal thin film, a mounting alignment mark, and a mounting precision mark window are provided on the back side of the substrate. Two or more electrode surfaces having either the anode or the cathode used as the common electrode are provided. The light sensitive surface is positioned approximately in the center between these two electrode surfaces. A highly precise mounting can therefore be achieved with the solder bump, even when mounting single light receiving elements. High precision mounting is also obtained when mounting light receiving element arrays. This type of light receiving element can be precisely positioned and bonded by solder bumps to a substrate having an optical fiber fitted in the V groove.

Light receiving device for use in optical fiber communications and the

A method of measuring the radius of curvature of the convex tip of a core protruding from the end of an optical transmission path is disclosed. The transmission path is implemented by an optical fiber. A measuring unit accommodating a condenser and an infrared camera is located to face the convex tip of the core. A semiconductor laser is connected to the end of the fiber remote from the convex tip. A laser beam issuing from the convex tip of the core is once condensed by the convex tip. The measuring unit determines the condensing point of the beam, and then measures the distance between the condensing point and the convex tip. Subsequently, after the space between the convex tip and the condenser has been filled with a medium different in refractive index from air, the measuring unit again measures the above distance. The radius of curvature of the convex tip is determined on the basis of a difference or a radio between the measured distances.

Method of evaluating an optical transmission path

The optical fibers are arranged in a V groove formed at the surface of a silicon substrate and a cover is provided thereon. An electrode for solder bump is respectively formed at the position opposed with each other to the substrate and cover. These substrate and cover are deposited with solder in order to fix the optical fibers. The substrate or cover is previously provided, at the end point part of the optical fibers, with the mark for the positioning in the longitudinal direction of the optical fibers. The optical fibers are positioned with this mark. Here, the side surface of the optical fibers is provided with the metallized area at the position located in the predetermined distance from the end point thereof. Before fixing with the cover, the optical fibers can be deposited automatically to the predetermined position without alignment due to the self-alignment effect between the mark and metallized area. Meanwhile, the optical element can be deposited with the solder bump without adjustment to the area near the end point of the optical fiber by utilizing the self-alignment. Here, it is also possible to form the mark to the substrate for measuring the mounting position of the optical element after deposition thereof.

Coupling structure of optical fiber and optical semiconductor element

The method for forming a tip of an array optical fiber disclosed is one in which an etching resistive material such as a photoresist is applied first on an end portion of a coated material covering constituent fibers of the array optical fiber, and then the ends of the constituent fibers are etched. Due to the presence of the etching resistive material, the etching solution does not dissolve the coated material. In an alternative method, the etching resistive material such as a photoresist is applied on a side surface of a tip portion of each constituent fiber of the array optical fiber exposed from the coated material, the tip portion is cut and flattened together with the etching resistive material, and the end faces of the constituent optical fibers are etched. The presence of the etching resistive material prevents the tip diameter of the constituent optical fiber from becoming small.

Method for forming tip of array optical fiber using etching process

An optical module has an optical wave-guide structure formed on a silicon substrate and a laser diode array solder bonded to first pads patterned on the silicon substrate in a self-aligned manner by virtue of surface tension of solder during a reflow stage, and the first pads are shaped into a rectangular parallelopiped configuration so as to make a ratio of a solder bump height to a pad width large without decrease of the volume of the solder bump, thereby generating large surface tension.

Optical module having self-aligned optical element and optical

In an apparatus for punching a metallic sheet to stamp out a bump and bonding it to a substrate, an AuSn sheet is heated to above a softening point thereof by a heater. A solenoid is energized to cause a punch and a die to stamp out a bump from the AuSn sheet. The bump is directly bonded to a substrate. The punch is made up of a shank portion and a punch portion. A punch holder for guiding the shank portion and punch portion with high accuracy molded integrally with the die. The punch is connected to the solenoid with the intermediary of a damper spring. When the bump hits against the substrate, the damper spring prevents it from chipping off or cracking due to an impact. Subsequently, another solenoid is energized to move the punch further downward, thereby pressing the bump against the substrate for a sufficient period of time.

Bump forming apparatus

The apparatus for forming a hemispherical micro-lens according to the present invention comprises a laser light oscillator 5 for irradiating laser light into one end 3a of an optical fiber 3, a far-field pattern (F.F.P.) detector 6 for detecting the shape of the F.F.P. of laser light emitted from the other end 3b of the optical fiber 3, discharge electrodes 1 for heating the end 3b of the optical fiber 3 and thereby forming a hemispherical microlens, and a discharge controller 2 for controlling the operation of the discharge electrodes 1 according to the shape of the detected F.F.P. With this apparatus, laser light is irradiated into one end surface 3a of an optical fiber 3, the other end surface 3b is heated to form a hemispherical microlens while measuring the F.F.P. of laser light emitted from this end surface 3b, and heating is halted according to the measured value of the F.F.P. It is preferable that the discharge controller 2 halt the heating operation when the diameter of the F.F.P. detected at the F.F.P. detector is approximately equal to a preset value, in particular the maximum value of the diameter of the F.F.P. This apparatus may also be applied in a case in which the ends 3b of a plurality of optical fibers arranged as an array are collectively heated and formed into hemispherical microlenses.

Apparatus and method for forming a hemispherical microlens at the end of

Optical coupling equipment of the invention for an optical semiconductor and an optical fiber comprises a optical semiconductor, an optical fiber optically coupled to the semiconductor, and a refraction index matching substance filling the space between the semiconductor and the fiber. The refraction index matching substance has a refraction index greater than 1 and smaller than the refraction index of the core of the fiber. The optical distance between the ends of the semiconductor and the fiber with the ends of convex tip changes in association with the refraction index of the refraction index matching substance. In the differences in refraction index between the core of the fiber, as measured on the convex tip, and the outside decreases, the position of the focus of the convex tip changes. Furthermore, if the substances exists outside the active layer, the radiation angle of the laser diode also decreases. As a result, the distance between the facing ends which provides the highest coupling efficiency increases, compared to the equipment lacking the substance.

Optical coupling equipment for an optical semiconductor and an optical

Disclosed is a method of forming bonding metal bumps on electrodes of a submount for use with an optical device array. Small bonding metal pieces are arranged on a transfer piece resting substrate so as to be aligned with the electrodes of the submount. Next, the bonding metal pieces thus arranged are transferred onto respective electrodes of the submount. In one embodiment, bonding metal pieces are preferably formed by punching a ribbon-shaped bonding metal and respectively fixed by a force of the punching operation directly onto the electrodes of the submount.

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Tokyo, Japan

Hiroshi Honmou