JP3125820B2 - Bidirectional module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional transmission module used in various optical communication equipment fields.

[0002]

2. Description of the Related Art FIG. 5 shows the structure of a conventional wavelength multiplexing bidirectional module (Japanese Patent Laid-Open No. 60-184216). The optical multiplexer / demultiplexer in which the interference film filter 57 is adhered to the light emitting element package 53, the light receiving element package 54, the common holder 55, and the glass block 56 is mounted on the ceramic substrate 51.

[0005] As shown in FIG. 5, a parallel beam having a wavelength λ 1 from a light emitting element package 53 passes through an interference film filter 57 and a glass block 56 and passes through a common holder 55.
Is focused on the optical fiber 52. On the other hand, the optical fiber 52
Is converted into a parallel beam by the common holder 55, is reflected by the interference film filter 57, passes through the glass block 56, and is focused on the light receiving element by the lens of the light receiving element package 54. Light emitting and receiving element packages 53, 54,
An optical multiplexer / demultiplexer in which an interference film filter 57 is bonded to a common holder 55 and a glass block 56 is integrated on a ceramic substrate 51.

In the bidirectional module of FIG. 5 having the above-described structure, optical multiplexing and demultiplexing is performed by the interference filter 57.
The multiplexing / demultiplexing characteristic has an advantage that it is possible to relatively easily obtain a multiplexing / demultiplexing characteristic with low crosstalk over a wide band since the degree of freedom in designing a filter is large. Further, since the light emitting element package 53, the light receiving element package 54, the glass block 56, and the common holder 55 are mounted on the ceramic substrate 51, there is an advantage that multi-mode optical fibers can be assembled without adjustment.

[0005]

In the above prior art, the multiplexing / demultiplexing glass block has an optical path as shown in FIG. 5, so that its size is limited and it is difficult to reduce the size. Further, since high precision is required for the processing accuracy of the glass block, it is difficult to reduce the price. Further, when a single mode fiber is used for the transmission line, it is necessary to perform high-precision optical axis adjustment at the time of assembling, so that the above-described module cannot be assembled without adjustment. That is, assuming that the optical axis direction is the Z axis, two axes X and Y axes perpendicular to the Z axis, the tilt θ of the XZ plane, the tilt φ of the YZ plane, and the five axes of the distance Z between the common holder lens and the optical fiber are simultaneously set. Since adjustment is required, the assembly process is complicated and the number of steps is large. Furthermore, when the case is hermetically sealed and fixed to prevent dew condensation, a large force is applied to the ceramic substrate to cause an optical axis shift, which causes a problem such as an increase in loss. Therefore, mass production and cost reduction are difficult.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide a small and low-cost bidirectional module.

[0007]

In order to achieve the above object, a waveguide type substrate comprising a directional coupler which can be easily mass-produced, and which can be reduced in size and cost is adopted. The device package has two axes (X axis,
Y-axis) Uses a light-emitting element package with a lens that can be used only by adjustment and is mounted on a module package. The light-emitting element package also functions as a light-receiving element to reduce the number of parts. By attaching a cylindrical lens, the Z-axis is not adjusted, and the X-axis and Y-axis adjustment tolerances can be made more relaxed than before. That is, in the present invention, a waveguide-type substrate having a cylindrical lens attached to an end face of the waveguide, and a light-emitting element package with a lens disposed at a position facing the end face, and integrated into the same module package. It is a characteristic.

[0008]

According to the present invention, a waveguide substrate having a directional coupler as a component has a multiplexing / demultiplexing function. By attaching a cylindrical lens to the waveguide end face of this substrate, the optical axis direction can be changed to Z
With respect to the two axes X and Y, which are perpendicular to the axis, the Z axis can be adjusted without adjustment, and the X and Y axes can be adjusted with less tolerance. Further, the light emitting element package is mounted at a position facing the end face of the waveguide on the side where the cylindrical lens is attached, the light emitting element package also functions as a light receiving element having a wavelength of λ1, and an optical fiber is fused to the other end face of the waveguide. By attaching it to a module package, it functions as a small, low-cost bidirectional module.

[0009]

FIG. 1, FIG. 2, FIG. 3, FIG.
This will be described with reference to FIG.

FIG. 1 is a simplified plan view of a principal part of a bidirectional module according to an embodiment of the present invention. In the figure, light having a wavelength λ1 from a light emitting element is emitted from a light emitting element package with a lens 8 and passes through a cylindrical lens 9 attached to an end face of the multiplexing waveguide 3 to form a multiplexing waveguide 3 and a common waveguide 5. And is coupled to the optical fiber 7a. on the other hand,
The light of wavelengths λ1 and λ2 from the optical fiber 7a is split by the directional coupling unit 2, and the light of λ1 propagates through the multiplexing waveguide 3 and the cylindrical lens 9 and is incident on the light emitting element package 8 with a lens. , The light emitting element functions as a light receiving element having the wavelength λ1. The light of λ2 propagates through the branching waveguide 4, and
The light propagates to the optical fiber 7b fused to the end face of the branching waveguide 4.

In the present invention, the lens and the light-emitting element are integrated in a hermetically sealed package 8 in advance, and this package is adjusted in position and coupled to the cylindrical lens 9 attached to the end face of the multiplexing / demultiplexing waveguide.

FIG. 3 shows the coupling tolerance between the light emitting element package and the waveguide in the X and Y axes. From this figure, it can be estimated that the adjustment of the X and Y axes can be eased. Since the coupling tolerance of the Z axis is less dependent on the Z axis,
No adjustment is possible. Further, the light receiving element package can be similarly coupled to the waveguide.

FIG. 2 shows another embodiment of the present invention. This embodiment operates in the same manner as the above embodiment. However, the difference from the above embodiment is that light of wavelength λ2 propagating from the directional coupler 2 to the branch waveguide 4 is reflected by the filter 10 and fused to the end face of the waveguide on the same side as the optical fiber 7a. To the optical fiber 7b. By doing so, there is an advantage that the optical fibers can be bundled on only one side and the space required as a bidirectional module is reduced.

In the present invention, the waveguide type substrate 1 and the light emitting element package 8 described above are integrated into a module package 6 and sealed.

Hereinafter, an example of an assembling method according to one embodiment (described in FIG. 1) will be described with reference to FIG. First, the module package 6 is metallized on one side, the optical fibers 7a and 7b are fused, and the waveguide substrate 1 on which the cylindrical lens 9 is fixed is Au.
/ Su eutectic high-temperature solder and the like, and light-emitting element package 8 is inserted from the side of module package 6,
After adjusting the position of the X and Y axes, the metal is fixed by laser welding or Pb / Su eutectic solder. At this time, in the Z-axis direction, as described above, non-adjustment assembly is possible with mechanical part processing accuracy. At this time, since the light emitting element is already hermetically sealed by the light emitting element package 8 with a lens, it is fixed by laser welding.
Even if it is not hermetically sealed and fixed at the time of solder fixing, it does not affect the reliability of the element. Also, when the module is sealed to prevent dew condensation, high-performance hermetic sealing is not necessary, so that the module can be sealed relatively easily.

[0016]

According to the present invention, a light emitting element package with a lens which can be easily coupled to a waveguide is used for a light emitting element by using a waveguide substrate having a directional coupler as a component in a multiplexing / demultiplexing section. Further, in order to improve the coupling, a cylindrical lens is used on the end face of the waveguide, and these are adjusted to only two axes from the conventional five axes in the module package, and the module is hermetically sealed. By making the element also function as a light receiving element and reducing the number of parts, mass production becomes possible,
It has the effect of reducing size and price.

[Brief description of the drawings]

FIG. 1 is a fragmentary plan view of an essential part of an embodiment of the present invention.

FIG. 2 is a fragmentary plan view of another embodiment of the present invention.

FIG. 3 is a diagram illustrating a coupling tolerance characteristic between a light emitting element package and a waveguide.

FIG. 4 is a perspective view showing the structure of one embodiment of the present invention.

FIG. 5 is a structural diagram of a conventional bidirectional module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Waveguide type substrate, 2 ... Directional coupling part, 3 ... Combined waveguide, 4 ... Branching waveguide, 5 ... Common waveguide, 6 ... Module package, 7a, 7b ... Optical fiber, 8 ... Light emitting element with lens Package 9 ... Cylindrical lens 10 ... Filter

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Kaneko 216 Totsuka-cho, Totsuka-ku, Yokohama-shi Inside the Information Communication Division, Hitachi, Ltd. (72) Inventor Jin Hashimoto 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Examiner, Nippon Telegraph and Telephone Corporation Ritsumasa Kobashi (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 6/12-6/42

Claims (2)

(57) [Claims] 1. A linear and waveguide substrate having an optical multiplexing and demultiplexing functions to form a directional coupling portion made of curved waveguide as components, and multiplexing waveguide light propagates to be multiplexed, demultiplexed placement and demultiplexing waveguide light propagates, and a common waveguide light and combined light to be demultiplexed is both propagate in a position facing the end surface of the multiplexing waveguide, a lens-attached light emitting device package The light emitting element transmits a light , and receives the light.
A bidirectional module, wherein an optical fiber is fused to the common waveguide, and the light emitting element package with the lens and the waveguide substrate are mounted in the same package. 2. The multiplexing waveguide , the demultiplexing waveguide and the shared waveguide.
2. The bidirectional module according to claim 1, wherein a cylindrical lens is attached to one end face of the through waveguide .