JP3125403B2 - Optical array module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical array module, and more particularly, to an optical coupling structure of a laser diode array module.

[0002] An optical array module, for example, a laser diode array module (LD array module) is an optical fiber array in which an LD array section in which a plurality of LD chips are arranged, a lens array section in which a plurality of lenses are arranged, and a plurality of optical fibers are arranged. The light is efficiently coupled by enlarging the minute light emission image of the LD chip to about the light receiving diameter of the optical fiber with a lens.

However, when the environmental temperature changes, there is a problem that the optical axis shifts due to the difference in thermal expansion of the constituent members and the optical coupling efficiency deteriorates, and it is required to efficiently couple light without being affected by the environmental temperature.

[0004]

2. Description of the Related Art As shown in a perspective view of FIG. 3, a conventional optical coupling structure of an LD array module comprises an LD array unit 11, a lens array unit 12, and an optical fiber array unit 13. The light beam emitted from the light emitting section 11b-1 of the LD array section 11 is transmitted to the optical fiber 13a by the convex lens 12b-1 of the lens array section 12.
And is optically coupled to the optical fiber array unit 13.

[0005]

However, according to such an optical coupling structure, if the ambient temperature changes, the optical coupling structure shown in FIG.
As shown in the schematic diagram showing the optical axis deviation of the above, since there is a difference in thermal expansion between the LD array unit 11, the lens array unit 12, and the optical fiber array unit 13 as shown by a two-dot chain line, each optical axis is The amount of light incident on the optical fiber 13a deviated from each other is reduced (a diagonal line rising to the right indicates a room temperature, and a diagonal line rising to the left indicates a temperature change), and the optical coupling efficiency is degraded.

[0006] In view of the above problems, an object of the present invention is to provide an optical array module that reduces the mutual optical axis shift due to the difference in thermal expansion of constituent members and improves the optical coupling efficiency.

[0007]

In order to achieve the above object, in an optical array module according to the present invention, an LD array unit having a light emitting unit arranged and mounted on a mount member and fixed to the mounting member; A lens array unit formed by aligning and forming a lens array plate formed by aligning convex lenses having an image magnification of M for expanding a light beam emitted from the unit, and an optical fiber for receiving a light beam emitted from the convex lens. An optical fiber array section fixed and aligned with the mount member, wherein the thermal expansion coefficients of the mount members are α, β, and γ, respectively, and γ is (M + 1) β−
The material to be Mα is selected and configured.

[0008]

As shown in the principle diagram of the present invention in FIG. 1, each mounting member 1 of the LD array unit 1, the lens array unit 2, and the optical fiber array unit 3 constituting the optical array module.
Let the thermal expansion coefficients of a, 2a, and 3a be α, β, and γ. At the time of optimal coupling at room temperature, the distance from the center (neutral point) C of each of the LD array unit 1, the lens array unit 2, and the optical fiber array unit 3 to a certain channel (the figure shows optical coupling of four channels). and x, the temperature change, respectively thermally expanded as indicated by the two-dot chain line, the respective shift distances, the light emitting portion _1b-1 Δx 1, the convex lens 2b-1 and [Delta] x _2, the optical fiber 3a-1 [Delta] x
_{Assume 3} . Further, the image magnification of the convex lens 2b-1 is set to M (= light emitting unit).
(Emission diameter of 1b-1 / reception diameter of optical fiber 3a-1), and assuming that the temperature change from room temperature is ΔT, Δx ₁ = α · ΔT · x Δx ₂ = β · ΔT · x Δx ₃ = γ · ΔT X is satisfied, and the mutual optical axis shift is reduced when the following expression is satisfied.

Δx ₁ + (Δx ₂ −Δx ₁ ) (M + 1) = Δx ₃ First term on left side; optical axis shift of light emitting unit 1b-1 due to thermal expansion Second term on left side; LD array unit 1, lens array unit 2 Light emitting part due to the difference in thermal expansion coefficient between the respective mounting members 1a and 2a
Optical axis shift between 1b-1 and convex lens 2b-1 Right side: Optical fiber due to thermal expansion of optical fiber array unit 3
Above the optical axis deviation of 3a-1, α · ΔT · x + (β · ΔT · x−α · ΔT · x) (M + 1) = γ · ΔT · x α + (β−α) (M + 1) = γ (M + 1) β−Mα = γ (1) For the convex lens 2b-1 having the optimum image magnification M, this (1)
Mount members 1a, 2 with thermal expansion coefficients α, β, γ that satisfy the formula
By selecting a and 3a and configuring the LD array unit 1, the lens array unit 2, and the optical fiber array unit 3, mutual optical axis shift due to a difference in thermal expansion can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention will be described below in detail with reference to the embodiments shown in the drawings. As shown in the perspective view of FIG. 2 (the reference numerals correspond to those in FIG. 1 and the same reference numerals are assigned), the optical coupling structure of the optical array module includes an LD array unit 1, a lens array unit 2, and an optical fiber array unit 3. Make up a plurality (Fig. 4
Channel).

The LD array section 1 has four light emitting sections.
An LD array chip 1b in which 1b-1 are aligned and a mount member 1a on which the LD array chip 1b is mounted and fixed with an adhesive are used. The material of the mount member 1a has a good heat radiation property and an LD array from the viewpoint of reducing thermal distortion. Thermal expansion coefficient α = almost the same as chip 1b
A copper-tungsten alloy of 6 × 10 ⁻⁶ / ° C. is used.

The lens array section 2 includes four convex lenses 2b-1
It is composed of a lens array plate 2b made of optical glass formed by aligning and a mounting member 2a for fixing and holding it with an adhesive,
As a material of the mount member 2a, an iron-nickel alloy having a thermal expansion coefficient β = 8 × 10 ⁻⁶ / ° C. which is almost the same as that of the optical glass is used. The image magnification M of the convex lens 2b-1 is the light emitting portion of the LD array unit 1.
The size of 1b-1 and the optical fiber 3a of the optical fiber array unit 3
"4" is adopted from the light receiving diameter of -1.

The optical fiber array section 3 comprises four optical fibers 3a-1 and a mounting member 3a having V grooves 3a-2 for inserting the optical fibers 3a and fixing them with an adhesive.
From equation (1), γ = (4 + 1) 8 × 10 ⁻⁶ -4 ·
Stainless steel having a coefficient of thermal expansion of 6 × 10 ⁻⁶ = 16 × 10 ⁻⁶ / ° C. is used.

As described above, by appropriately selecting the mount members having the thermal expansion coefficients α, β, and γ satisfying the expression (1) and the convex lens having the magnification ratio M, the difference in thermal expansion caused by the change in the environmental temperature can be obtained. Since the mutual optical axis deviation can be reduced, the reduction of the optical power can be suppressed and the optical coupling can be efficiently maintained.

[0015]

As described in detail above, according to the present invention,
Since an optical axis shift due to a change in environmental temperature can be reduced, an industrially useful effect such as providing an optical array module having excellent temperature characteristics and high optical coupling efficiency can be provided.

[Brief description of the drawings]

FIG. 1 is a principle diagram according to the present invention.

FIG. 2 is a perspective view of one embodiment according to the present invention.

FIG. 3 is a perspective view according to the prior art.

FIG. 4 is a schematic view showing an optical axis shift due to a difference in thermal expansion of FIG. 3;

[Explanation of symbols]

1 is an LD array unit 2b is a lens array plate 1a, 2a, 3a is a mounting member 2b-1 is a convex lens 1b is an LD array chip 3 is an optical fiber array unit 1b-1 is a light emitting unit 3a-1 is an optical fiber 2 is a lens array Department

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuhiko Kobayashi 2-1-1 Kitaichijo Nishi, Chuo-ku, Sapporo, Hokkaido Inside Fujitsu Hokkaido Digital Technology Co., Ltd. (72) Mitoyo Obata Kitaichijo, Chuo-ku, Sapporo 2-1-1 Nishi Fujitsu Hokkaido Digital Technology Co., Ltd. (56) References JP-A-4-116507 (JP, A) JP-A-4-166903 (JP, A) JP-A-4-301810 (JP) , A) JP-A-5-121710 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/24-6/42

Claims (1)

(57) [Claims] 1. An LD array chip (1) in which an LD array chip (1b) in which light emitting units (1b-1) are aligned is mounted and fixed on a mounting member (1a), and the light emitting unit (1b-1) A lens array unit (2) formed by fixing and holding a lens array plate (2b) formed by aligning convex lenses (2b-1) having an image magnification M for expanding the emitted light beam to a mount member (2a); An optical fiber array section (3) in which an optical fiber (3a-1) for receiving a light beam emitted from the convex lens (2b-1) is aligned and fixed to a mount member (3a), and each of the mount members (1a , 2a, and 3a) are selected from materials whose thermal expansion coefficients are α, β, and γ, respectively, and γ is (M + 1) β−Mα.