Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2001-03-20
2003-11-11
Font, Frank G. (Department: 2877)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S049000
Reexamination Certificate
active
06644867
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical head comprising mount materials onto which an optical element and an optical fiber array are fixed, more particularly to such optical heads including an angle formed between a light emitting/receiving face of the optical element and an inclined face of a mount material for fixing the optical fiber array.
2. Description of Related Art
An conventional optical head comprises a mount material for fixing an optical element such as light receiving element or light emitting element and a mount material for fixing an optical fiber array to which an optical fiber is connected, wherein the optical fiber is optically connected to the optical element.
FIG. 3
shows an optical head having a conventional light emitting element. An LD array
10
is provided such that a plurality of laser diodes are transversely arranged. A mount material
30
is made of a AIN ceramics with high heat conductivity, metalization for soldering is applied to its surface, and a wiring pattern
31
and a drive IC
35
bonded by an electrode of the LD array
10
and a wire
32
are arranged. The LD array
10
is fixed to the mount material
30
by means of soldering so that light emissions ejected from the LD array
10
are generally coincident with each other.
On the other hand, an optical fiber array
20
punches a V groove
23
on a support substrate
22
in order to position an optical fiber
21
, and a plurality of optical fibers
21
are arranged to be housed in the V groove
23
. These optical fibers are covered with a cap substrate
24
, from the top, and are fixed by sheet shaped soldering, thereby forming an integral block
25
.
At a position between the optical fiber array
20
and the LD array
10
are optically coupled with each other, a support substrate
22
is protruded on the top face of a mount body
40
; a spacer portion
34
is extruded on the side face of the mount material
40
, and the spacer portion
34
are bonded w the side face of the mount body
40
. In addition, this optical head is sealed with air tightness in a package by leading out an optical fiber or lead wire, whereby a parallel light transmission module is provided. In addition, an end face of the optical fiber
21
with which the LD array
10
is optically coupled is positioned at an end face of a block
25
, and is formed so as to be opposed to a light emission plane of the mount material
30
having the LD array
10
mounted thereon.
Next, in order to directly emit light emission from an light emitting element to a large diameter end face of an optical fiber or to emit the light emission expanded or contacted by a lens, an interval between a light emission element required for fine adjustment and the end face of the optical fiber is spaced, adjusted, and fixed when a connection face between mounted materials fixed to each other is defined as a reference. This derives from light intensity in a direction orthogonal to an optical axis of an optical element for example, a laser diode and light intensity averaging between a plurality of fibers of the optical head after light axis alignment.
That is, the light intensity in a direction orthogonal to an optical axis of a laser diode draws a Gaussian curve shape when an optical axis is defined as a center axis However, when a point orthogonal to the optical axis is spaced from a laser diode, a top of the curve is lowered, and the gradient is gentle. When the top of the curve is low, light intensity is lowered. On the other hand, when the gradient is gentle, even if slight deviation from the optical axis occurs in a vertical direction, it indicates that a small rapid change occurs with light intensity.
In addition, in the optical head, even if the same optical intensity is input to a plurality of configured fibers, large deviation in light intensity must not be present between fibers due to deviation from the light axis.
The arrangement precision of a plurality of optical elements and the arrangement precision of a plurality of fibers must be permitted to some extent in view of manufacture. This means that another optical element and an optical fiber deviation from an optical axis even if an arbitrary optical element and the corresponding optical fiber are completely aligned with the axis. Even under such circumference, as means for preventing large deviation in light intensity between fibers, there has been conventionally performed means for spacing an optical element and an optical fiber from each other by a predetermined value. This method utilizes the fact that, although light intensity is lowered as deviation from an optical element is more significant as described above, the variation rate of light intensity in a direction vertical to an optical axis is gentle.
Specifically, a light emission element is fixed to a mount material by means of soldering; an optical fiber is pressed by from the top arranged and housed in a support substrate having a V groove punched thereon, and is fixed by means of soldering; and the support substrate is fixed to a top face of the mount material. At this time, when an end face of the mount material fixing an optical fiber array is defined as a reference face, the fixing position of the light emission element is adjusted by the mount material via a spacer for ensuring a design space. In addition, the position of a support substrate is fine adjusted while sensing the light receiving capability of an optical fiber fixed to the support substrate against the adjustment light from the light emission element.
However, in order to ensure this spacing distance, positional adjustment is cumbersome because it is intensively influenced by the dimensional precision of a spacer and the positional precision on the mount material for the light emission element. Thus, there has been a growing need for improvement of means capable of simplifying positional adjustment using check light by improving precision of adjustment technique utilizing a reference face of the mount material.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided an optical head including a mount material for fixing an optical element and a mount material for fixing an optical fiber array. The optical fiber is optically connected to the optical element. An angle formed between a light emission/receiving face of the optical element and an inclined face of the mount material for fixing the optical fiber array is 1 to 8 degrees. In this manner, an angle formed between a light emission/receiving face and an end face of an optical fiber is greater than 1 degree. Thus, noise produced by reflection light deriving from a light receiving face or an end face of an optical fiber opposed to a light emitting/receiving element is reduced as compared with a case in which the conventional light emission/receiving face and the end face of the optical fiber are substantially parallel to each other, and a failure with optical signal transmission can be prevented. In addition, an angle formed between the light emission/receiving face and an end face of the optical fiber is smaller than 8 degrees, and thus, bonding efficiency is improved. In addition, an end face can be shaved with high processing precision, and thus, the shaved portion can act as the above spacing distance. Therefore, the spacing distance can be ensured with high precision.
According to a second aspect of the present invention, there is provided an optical head wherein thermal expansion rates of the mount material of the optical element and the mount material of the optical fiber array are substantially equal to a thermal expansion rate of the optical fiber array material. In this manner, the thermal expansion rates of mount materials is substantially identical to each other. Thus, even if these materials are used under severe environment such that a temperature difference is large, there is no thermal contraction difference between the mount materials, and an axial deviation in optical signals fixed thereto and t
Burr & Brown
Font Frank G.
Kianni Kevin C
NGK Insulators Ltd.
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