Optical module, method for manufacturing optical module and optical communication apparatus

Abstract

The present invention is to reduce the package cost and secure the high reliability in an optical module having an optical device and an optical fiber. In the case where the optical module is constituted by use of a pre-molded plastic package, a molding resin is flown parallely with the optical axis direction of the optical fiber on which the plastic package is formed by injection molding. Further, in the case where the plastic package is formed by the comprehensive molding, the flowing direction of resin is parallel with the optical axis direction of the optical fiber to be installed. In the case where a resin case is used, the package exhibits the high rigidity and low thermal expansion properties in connection with the flowing direction of resin, thus reducing the external stress and thermal stress applied to the optical fiber. Accordingly, the high reliability is secured. In the case of the comprehensive molding, the molding pressure applied to the optical fiber is reduced. Therefore, the high reliability is secured.

Description

[0001] The present invention relates to a resin molding type optical module having an optical device and an optical fiber packaged with a resin, an optical fiber communication apparatus using the resin molding type optical module, and an optical communication system.[0002] Recently, great demands for lowering the cost of the optical module have been made in order to introduce the optical fiber communication system into the subscriber network system on a full scale. From a viewpoint of this, with respect to the packaging technology, a resin sealing method (a plastic package method) is influential in place of a hermetic sealing method for a metallized package or a ceramic package which has heretofore occupied the mainstream in the field of optical devices. This is because the resin sealing method is suitable for mass-and inexpensive production.[0003] In the past, in the field of general semiconductor devices such as LSI and hybrid IC, the following various methods have been known as r...

AI Technical Summary

Benefits of technology

[0021] A first object of the present invention is to secure the reliability of an optical module while reducing the molding cost of a resin case type package.

[0022] A second object of the present invention is to secure the long-term stability of an optical coupling between an optical element and an optical fiber while reducing the molding cost of a resin case type package. That is, it is to provide a means which suppresses deformation of the resin case caused by the change in temperature and the external force to reduce stress applied to constituent members of the optical module.

[0023] A third object of the present invention is to provide a means for further enhancing the moisture resistance of constituent members of an optical module such as an optical device and an optical fiber while reducing the molding cost of a resin case type package. Thereby, the long-term stability of the optical module is to be secured. By the joint use with the means for securing the long-term stability of the optical coupling between the optical device and the optical fiber mentioned in the above second object, it is possible to secure more sufficient and long-term stability of the optical module.

Problems solved by technology

The plastic package is influential for lowering the cost of the optical module as compared with the metallized package or the ceramic package, but has difficulties such that generally, the moisture permeability is high, and the coefficient of thermal expansion is large.

These factors synthetically lower the reliability of the plastic package.

In particular, in the semiconductor laser module, a demand relative to such a position is severe.

Any of the aforementioned prior arts have both merits and demerits with respect to such demands as noted above, and fail to respond to the demands of the current industrial world.

Considering the dimensional accuracy of the receptacle itself and the deformation of the receptacle caused by the insert- and pull force of connector and the thermal expansion, the module in Article 2 can be applied to a light emitting diode having a large spot size but is not suitable for a laser diode having a small spot size.

Accordingly, the thermal stress and the external force are concentrated on the interface between the bare fiber portion and the jacket portion to bring forth a problem in that the bare fiber is broken.

There is a difficulty that since when the casting is performed, voids tend to be mixed, water moves in from the channel to corrode optical ends of optical devices and electrodes.

Further, reference is not made to materials for the resin case and molding method.

In this technique, various problems occurs unless various items mentioned above are sufficiently selected.

That is, due to a difference in the coefficient of thermal expansion between the bare fiber (quartz glass) and the resin case, the bare fiber protrudes from the jacket, and the crack occurs in the bare fiber due to the concentration of stress.

Further, vapor permeated into the hollow case becomes dewed on the surface of the optical device or the bare fiber to give rise to the corrosion of the optical device, or to progress the growth of crack, resulting in the rupture of the bare fiber.

However, the elastic modulus of the resin package member and the anisotropy of the thermal coefficient of expansion of the resin package member are not taken into consideration.

As briefly mentioned above, the prior arts lack some consideration in relation to the number of parts, thermal stress and moisture resistance concerned with the cost.

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