OPTICAL MODULE AND METHOD OF MANUFACTURING THE SAME

Abstract

A receptacle with lens can be mounted to an optimum position without monitoring an optical power. In an optical module constructed by a photonic device, a photonic device pedestal mounting the photonic device thereto, a TO-CAN stem, a cap with window glass, and a receptacle with lens, the TO-CAN stem is fitted to the receptacle with lens, the receptacle with lens is provided with a lens which can obtain a predetermined coupling efficiency between the photonic device and an optical fiber mounted to the receptacle with lens, and the TO-CAN stem is fitted with no alignment and bonded and fixed to the receptacle with lens. Therefore, the optimum mounting position of the receptacle with lens is achieved only by the mounting accuracy of the photonic device and the parts dimensional tolerances of the TO-CAN stem and the receptacle with lens without directly monitoring the optical power from the photonic device.

Claims

1. An optical module comprising: a photonic device; a photonic device pedestal mounting the photonic device thereto; a TO-CAN stem; a cap with window glass; and a receptacle with lens, wherein the receptacle with lens is fitted into the TO-CAN stem by mounting the photonic device to the center of the TO-CAN stem at a predetermined position accuracy.

2. The optical module according to claim 1, wherein the receptacle with lens is provided with a lens in which a predetermined coupling efficiency with the optical fiber mounted to the photonic device and the receptacle with lens can be obtained, and the receptacle with lens is fitted with no alignment to the TO-CAN stem and is fixed by bonding.

3. The optical module according to claim 2, wherein the coupling efficiency of the lens with the optical fiber is equal to or more than 30%.

4. The optical module according to claim 1, wherein the photonic device is mounted to a photonic device mounting surface of the TO-CAN stem at a position of being ±30 μm with respect to the center of the optical axis on the basis of a side wall dimension of the TO-CAN stem, and a sum of dimensional tolerances of an inner wall of the receptacle with lens and a stem side wall of the TO-CAN stem is set to be equal to or less than ±50 μm.

5. The optical module according to claim 1, wherein the optical fiber positioned at the center of the optical connector mounted to the receptacle with lens is a hard plastic clad fiber having a core diameter of ϕ3200 μm or a plastic optical fiber having a core diameter of ϕ980 μm.

6. The optical module according to claim 2, wherein the optical fiber positioned at the center of the optical connector mounted to the receptacle with lens is a hard plastic clad fiber having a core diameter of ϕ200 μm or a plastic optical fiber having a core diameter of ϕ980 μm.

7. A method of manufacturing an optical module including a photonic device, a photonic device pedestal mounting the photonic device thereto, a TO-CAN stem, a cap with window glass, and a receptacle with lens, the method comprising: a step of mounting the photonic device pedestal to the vicinity of a photonic device mounting surface of the TO-CAN stem; a step of recognizing a stem side wall of the TO-CAN stem mounting the photonic device thereto by an image camera and determining the center of the photonic device mounting surface, thereby mounting the photonic device to the photonic device mounting surface at a position of being away from the center at a predetermined position; a step of mounting the cap with window glass to the photonic device mounting surface of the TO-CAN stem; and a step of fitting an inner wall of a receptacle with lens previously manufactured at a predetermined dimensional tolerance accuracy and the side wall of the TO-CAN stem, and curing and fixing with an adhesive agent of an ultraviolet cure resin or a thermoset resin.

8. The method of manufacturing the optical module according to claim 7, wherein the mounting accuracy of the photonic device is set to be equal to or less than ±30 μm from the center of the TO-CAN stem.

9. The method of manufacturing the optical module according to claim 7, wherein the dimensional tolerance of the inner wall of the receptacle with lens and the side wall of the TO-CAN stem is equal to or less than ±50 μm.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0029] FIG. 1 is a view showing an optical module according to an embodiment of the present invention.

[0030] FIG. 2 is a view describing an assembling procedure (a manufacturing method) of the optical module according to the present invention.

[0031] FIG. 3 is a view showing a conventional optical module.

[0032] FIG. 4 is a view describing an assembling procedure (a manufacturing method) of the conventional optical module.

[0033] FIG. 5 is a view showing a coupling efficiency caused by a gap between a photonic device and an optical fiber.

DESCRIPTION OF EMBODIMENTS

[0034] A structure of an optical module according to the present invention is shown in FIGS. 1 and 2 by exemplifying an optical transmitter module.

[0035] More specifically, as shown in FIGS. 1 and 2, the present invention is constructed by a photonic device (a vertical resonator surface emitting laser: VCSEL) 10, a pedestal 11 mounting the photonic device 10 thereto, a TO-CAN stem 12 mounting the photonic device pedestal 11 thereto, a cap with window glass 13 protecting the photonic device 10, and a receptacle with lens 15 formed by integrating an aspheric lens portion 15b and a sleeve portion 15a inserting an optical connector 16 having an optical fiber 17 in a center thereof. Here, an inner wall 15c of the receptacle with lens 15 is fitted to a side wall 12b of the TO-CAN stem 12, and is fixed to the cap with window glass 13 by an adhesive agent 14.

[0036] In the meantime, in order to achieve an optical transmitter module emitting a predetermined light output by means of the fitting of the receptacle with lens 15 to the TO-CAN stem 12 mentioned above, a mounting accuracy of the photonic device 10 mounted to the TO-CAN stem 12 and a dimensional accuracy of the receptacle with lens 15 are important.

[0037] An axial gap and a coupling efficiency between the photonic device 10 and the optical fiber 17 of the optical connector 16 have been evaluated for outputting a necessary accuracy for the mounting accuracy of the photonic device and the dimensional accuracy of the receptacle with lens 15. An example of the evaluation thereof is shown in FIG. 5.

[0038] In the present example, the measurement was made by using the photonic device 10, and the optical connector 16 having at the center thereof the optical fiber 17 inserted into the sleeve portion 15a of the receptacle with lens 15 and having a core diameter ϕ200 μm.

[0039] As shown in FIG. 5, a horizontal axis indicates an amount of position gap (μm) in X and Y directions between the photonic device 10 and the fiber 17 positioned at the center of the optical connector 16 and having a core diameter ϕ200 μm, and a vertical axis indicates what rate of the light emitted from the photonic device 10 enters into the optical fiber 17 having the core diameter ϕ200 μm. This is generally called as a coupling efficiency.

[0040] Here, it is known that the greater the position gap between the photonic device 10 and the optical fiber 17 is, the smaller an optical power coupled to the optical fiber 17 is. For example, in a case where 30% or more of the light output of the photonic device 10 is taken into the optical fiber 17 having the core diameter ϕ200 μm, it is necessary to suppress the amount of position gap between the photonic device 10 and the optical fiber 17 to ±80 μm or less. On the basis of this result, the optical module can be easily and rapidly assembled while deleting the aligning step and system which have been conventionally essential, as long as the mounting gap between the photonic device 10 and the optical fiber 17 can be suppressed to ±80 μm or less by performing a dimensional management of the constructing parts.

[0041] In the present embodiment, in order to suppress the mounting gap between the photonic device 10 and the optical fiber 17 to ±80 μm or less, an amount of gap of the photonic device 10 from the center of the photonic device mounting surface of the TO-CAN stem 12 is set to be equal to or less than ±30 μm. Further, a sum of the dimensional tolerances of the inner wall 15c of the receptacle with lens 15 and the stem side wall 12b of the TO-CAN stem 12 is set to be equal to or less than ±50 μm.

[0042] Next, a description will be given in detail of an assembling procedure (a manufacturing method) of the optical module according to the present embodiment with reference to FIG. 2.

[0043] The photonic device pedestal 11 is mounted to the vicinity of the center of the photonic device mounting surface 12a of the TO-CAN stem 12 with a silver paste. Next, the photonic device (vertical resonator surface emitting laser: VCSEL) 10 is mounted to the photonic device mounting surface 12a at a position which is ±30 μm or less away from the center, by recognizing the stem side wall 12b of the TO-CAN stem 12 by an image camera, and determining the center of the photonic device mounting surface 12a.

[0044] Next, for the purpose of protecting the photonic device 10, the cap with window glass 13 is mounted to the photonic device mounting surface 12a of the TO-CAN stem 12. Finally, the side wall 12b of the TO-CAN stem 12 is fitted to the inner wall 15c of the receptacle with lens 15 previously manufactured at a totally ±50 μm or less dimensional tolerance accuracy, and is thereafter cured and fixed by the adhesive agent 14 such as the ultraviolet cure resin or the thermoset resin.

[0045] The present embodiment exemplifies a case where the applied optical fiber 17 is the hard plastic clad fiber having the core diameter of ϕ200 μm, and the maximum value of the amount of gap is set to ±80 μm on the basis of an allowable mounting tolerance thereof. However, the present invention is not limited to this, but the optical fiber may be a plastic optical fiber, for example, having a core diameter of ϕ980 μm. Since the required tolerance varies due to the core diameter of the applied optical fiber 17 and the used optical power, the mounting accuracy of the photonic device 10 and the dimensional accuracies of the TO-CAN stem 12 and the receptacle with lens 15 are determined along therewith.

[0046] In the meantime, in a case of the optical receiver module, the mounting accuracy of the light-receiving semiconductor device and the dimensional tolerance accuracies of the parts are decided by previously comprehending the tolerance between the optical fiber and the light-receiving semiconductor device and setting the tolerance to an allowable tolerance thereof or less, in the same manner.