Optical assembly with integrated lens protrusion

Details Optical assembly with integrated lens protrusion Optical assembly with integrated lens protrusion

2002-06-11

2004-09-28

Sanghavi, Hemang (Department: 2874)

Optical waveguides

With optical coupler

Input/output coupler

C385S034000, C385S078000, C385S093000

Reexamination Certificate

active

06798949

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical assemblies, and more particularly to an optical assembly used in a Dense Wavelength Division Multiplexer (DWDM).
2. Description of the Prior Art
As optical fiber technology is being more broadly applied in the telecommunications, data communications and community antenna television (CATV) industries, the fiber optic component industry is now confronted with increasingly demanding requirements for good performance and high reliability. Currently, most design and manufacturing of in-line fiber optic components are based on optical collimators, which provide low-loss light transmission from the input fiber to the output fiber through an optical element. Optical collimators are basic building blocks of fiber optic components. The reliability and level of performance of fiber optic components depends heavily on the reliability and performance characteristics of their optical collimators.
A Graded Index (GRIN) lens is a popular optical element which is utilized in an optical collimator for collimating scattered light. As show in
FIG. 1
, a conventional optical collimator
18
comprises an input optical fiber
10
, an output optical fiber
11
, a glass ferrule
12
, and a GRIN lens
13
. A through hole
121
defined in the ferrule
12
receives the optical fibers
10
,
11
therein. The ferrule
12
and the GRIN lens
13
are aligned and fixed in a glass inner tube
15
. A stainless steel tube
16
encloses the glass inner tuber
15
, thereby providing mechanical protection. A filter
14
is attached to an end face
132
of the GRIN lens
13
with the help of epoxy resin
17
.
The conventional optical collimator has some disadvantages. First, the filter
14
is directly attached to a surface of the GRIN lens
13
with the epoxy resin
17
. When the resin heats up during use, the filter
14
is subjected to uneven heating. This changes and adversely affects performance of the filter
14
. In addition, humidity created by the epoxy resin
17
adversely affects performance of the GRIN lens
13
. Second, accurate alignment between the ferrule
12
and the GRIN lens
13
depends on accurate formation of the inner tube
15
. Therefore, the inner tube
15
must be made with unduly high precision. Third, the GRIN lens
13
is conventionally made by an ion exchange method, which requires that, the GRIN lens
13
must be further polished after initial formation. Furthermore, chemicals used in the ion exchange method are harmful to users and pollute the environment.
Recently, a molded collimating lens
23
as shown in
FIG. 2
has been used in an optical collimator instead of a GRIN lens. The collimating lens
23
is made by a molding method. The collimating lens
23
has an aspherical forward face
232
and an oblique rearward face
231
. Molded optical collimating lenses overcome the disadvantage of environmental pollution. However, a molded lens has the curved face
232
, therefore fixing a filter to the curved face
232
is inconvenient. A copending application with an unknown serial number filed on Jun. 5, 2002, titled “OPTICAL COLLIMATOR WITH MOLDING LENS”, with the same inventors and the same assignee as the present invention, discloses one approach to this problem.
An improved optical assembly overcoming the above-described numerous disadvantages is desired.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an inexpensive optical assembly which has good optical performance.
Another object of the present invention is to provide an optical assembly that allows easy and precise assembly of its optical components.
A further object of the present invention is to provide an optical assembly that is environmentally friendly.
To achieve the above-mentioned objects, an optical assembly in accordance with the present invention comprises an input optical fiber and an output optical fiber, a glass ferrule receiving the input and output optical fibers therein, a molded lens, and a filter. The molded lens is fixed to the ferrule, and comprises a solid cylindrical main body with an annular-shaped protrusion extending from a forward end of the main body. The main body comprises an oblique rearward end face and an aspherical forward end face opposite to the rearward end face. The ferrule has an oblique forward end face which is fixed close to and substantially parallel with the oblique rearward end face of the molded lens. The filter is attached onto an end face of the annular protrusion.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompany drawings, in which:


REFERENCES:
patent: 4834494 (1989-05-01), DeMeritt et al.
patent: 6582135 (2003-06-01), Brun et al.
patent: 6694077 (2004-02-01), Liu et al.
patent: 2002/0076151 (2002-06-01), Kinard et al.

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