JP2005284015A - Optical module and optical fiber used for same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical module which is manufactured inexpensively by adopting a resin sealed type while preventing the reduction in optical output due to the resin seal. <P>SOLUTION: The optical module is such a type that an optical semiconductor element 3 and an optical fiber 1 are optically connected and fixed on a substrate 5, the optical semiconductor element 3 and the end of the optical fiber 1 are covered and sealed with a transparent resin material 4, the optical fiber 1 has a lens, the refractive index of the convex lens 2 of the optical fiber 1 is larger than the refractive index of the transparent resin material 4. The effect of the convex lens 2 is preserved even in the resin sealed type optical module because the refractive index of the convex lens 2 of the optical fiber 1 is larger than the refractive index of the transparent resin material 4, a light beam is refracted in the sealed resin and focused on the core of the optical fiber, thus the reduction in the coupling efficiency (optical output) due to the resin sealing is prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical module with improved light output and an optical fiber used therefor.

The optical module includes an optical semiconductor element such as a laser diode (LD) or a photodiode (PD), a lens, and an optical fiber. For example, since the light beam oscillated from the LD has a spread, in order to improve the optical output of the optical module, it is necessary to concentrate more light beams oscillated from the LD onto the optical fiber. In order to refract a light beam having a spread by a lens and guide it to the core of the optical fiber, there is an optical fiber with a lens in which the refractive action of the lens is made at the tip of the optical fiber.
In order to give a lens effect to the front end surface of the optical fiber, a wedge-shaped lens is formed by polishing the front end portion of the glass fiber, and an inclined surface is formed with respect to the optical axis of the light beam. There is a light source coupling optical fiber interface that makes it easy to focus the light beam on the core of the optical fiber because the light beam that radiates from the LD is refracted on the inclined surface due to the difference in refractive index with respect to the optical fiber (see, for example, Patent Document 1). ).

Japanese Patent No. 3067968 (first page)

In the optical module, in the spatial optical system optical module in which the space between the constituent members is air, the light beam oscillated from the LD is optically coupled to the optical fiber by the light source coupling optical fiber interface of Patent Document 1. However, the resin-encapsulated optical module in which the optical system is covered with a resin has a problem that the lens effect in the light source coupling optical fiber interface disappears.
That is, the resin-encapsulated optical module has a structure in which an optical semiconductor such as an LD or PD and an optical system at the tip of a lens or optical fiber are filled with a transparent resin material, and is inexpensive. Silicone resin and epoxy resin are used for the transparent resin material, and the refractive index of the transparent resin material is about 1.5. On the other hand, since the fiber is glass and has a refractive index of 1.45 to 1.5, when the transparent resin material is filled, the optical medium is refracted at the contact interface between the lens portion at the tip of the optical fiber and the transparent resin material. Since there is almost no difference in rate, it is difficult to refract the light beam and focus it on the core.

  The present invention has been made to solve such a problem, and obtains an optical module that is resin-sealed and inexpensive, and that prevents a decrease in light output due to resin sealing, and an optical fiber used for the same. With the goal.

  A first optical module according to the present invention includes an optical fiber, an optical semiconductor element optically coupled to the optical fiber, a transparent resin that seals an optical system between the optical fiber tip and the optical semiconductor element. In the optical module provided with a material, the optical fiber has a convex lens having a refractive index higher than that of the transparent resin material at the tip.

  The first optical module of the present invention includes an optical fiber, an optical semiconductor element optically coupled to the optical fiber, a transparent resin material that seals the optical fiber tip and the optical system between the optical semiconductor elements. In the optical module, the optical fiber has a convex lens having a refractive index larger than the refractive index of the transparent resin material at the tip, is a resin-sealed type, is inexpensive, and has a light output by resin sealing. Reduction can be prevented.

Embodiment 1 FIG.
FIG. 1 is a plan view of the optical module according to Embodiment 1, which is a resin-encapsulated optical module.
That is, the optical semiconductor 1 is mounted on the substrate 5, a power supply circuit to the optical semiconductor device 3 is formed by wire bonding or the like, and the optical fiber 1 is bonded to the substrate 5 so as to be optically coupled with the optical semiconductor device 3. The optical module is obtained by fixing with solder and sealing with a transparent resin material 4 so as to cover the optical semiconductor element 3 and the tip of the optical fiber 1.
Here, the optical fiber 1 used in the optical module of the present embodiment is an optical fiber with a lens, and has a convex lens having a refractive index larger than the refractive index of the transparent resin material at the tip. By placing the optical semiconductor element 3 near the spot (light emitting point or light receiving point) and electrically operating the optical semiconductor element 3, optimal optical coupling position alignment is performed in the optical axis direction and the optical axis vertical direction. Yes.
Since the refractive index of the convex lens 2 of the optical fiber 1 is larger than the refractive index of the transparent resin material 4, the lens effect of the convex lens 2 is maintained even in the resin-sealed optical module, and the sealing resin and the convex lens are maintained. The light beam can be refracted at the interface with the optical fiber and focused on the core of the optical fiber, preventing a decrease in coupling efficiency (light output) due to resin sealing, improving environmental resistance, Without using individual lenses, the number of parts can be reduced, and a low-cost resin-encapsulated optical module can be obtained.

Embodiment 2. FIG.
FIG. 2 is a plan view of an optical fiber with a lens according to Embodiment 2 of the present invention, in which an optical fiber main body 1b whose end face is cut vertically and a convex lens 2 made of silicon are joined at the end face of the optical fiber main body 1b. The spherical radius of the convex lens 2 is a hemispherical lens centered on the optical axis of the optical fiber.
In the optical module of Embodiment 1, the refractive index of a silicone resin or an epoxy resin that is generally used as a transparent resin material is around 1.5.
In the optical fiber with a lens according to the present embodiment, the convex lens 2 is made of silicon and has a refractive index of 3.448, which is sufficiently higher than the refractive index of the transparent resin material 4 for sealing. It can be condensed well. Silicon is a material that transmits light in the optical wavelength 1.3 μm band and 1.5 μm band for optical communication applications, and the refractive index of glass generally used for optical fibers is 1.45 to 1.5. The refractive index is large compared.
Therefore, due to the difference in refractive index between the transparent resin material and the convex lens 2 of the optical fiber, the light beam that radiates from the LD is refracted on the inclined surface and more incident on the core 1a of the optical fiber. The optical fiber cladding (having a lower refractive index than the core) repeatedly reflects, and the light propagates in a state where the light is confined in the core.

It is a top view of the optical module of Embodiment 1 of this invention. It is a top view of the optical fiber with a lens of Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber, 1b Optical fiber main body, 2 Convex lens, 3 Optical semiconductor element, 4 Transparent resin material.

Claims (2)

An optical module comprising: an optical fiber; an optical semiconductor element optically coupled to the optical fiber; and a transparent resin material that seals an optical system between the tip of the optical fiber and the optical semiconductor element. An optical module, wherein the fiber has a convex lens having a refractive index larger than that of the transparent resin material at a tip thereof. An optical fiber used in the optical module according to claim 1, comprising an optical fiber main body and a convex lens provided on an end face of the optical fiber main body, wherein the convex lens is made of silicon. .

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