JP2946805B2 - Terminal for optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal for an optical device, and more particularly to a terminal for an optical disk having a built-in single mode fiber fixed to the optical device for optically connecting the optical device and an optical connector.

[0002]

2. Description of the Related Art Conventionally, this type of optical device terminal has a structure in which a single mode fiber is held and fixed to a cylindrical capillary member having an inner diameter slightly larger than the inner diameter of a single mode fiber for transmitting light in a single mode. It has become. Optical devices in which this type of optical device terminal is used include an optical fixed attenuator, an optical connector, an optical filter, an optical semiconductor module, and the like.

[0003]

[SUMMARY OF THE INVENTION Generally when the first single mode fiber connected to another single mode fiber, the LP ₁₁ mode, which is one of the multimode caused by axial displacement of the connecting portion. When transmitting the light at both ends of the first single mode fiber short connected to the other single-mode, LP ₀₁ is a first single mode LP ₁₁ mode and the original propagation mode caused by the incident end of the fiber mode travels while interfering with the first single-mode fiber is divided again LP ₀₁ mode and the LP ₁₁ mode by axial displacement of a single mode fiber outgoing end side. Due to such a phenomenon, the coupling efficiency of light to another single-mode fiber on the emission end side has a characteristic that periodically changes with wavelength.

[0004] Such an optical device terminal using a single mode fiber or an optical device using the same has a drawback that the transmission loss is changed by a slight change in the wavelength of the light used. Further, there is a problem that a slight fluctuation of the wavelength is converted into fluctuation of the light intensity by passing through the optical device or the terminal for the optical device, thereby generating noise.

[0005]

According to the present invention, there is provided a terminal for an optical device, comprising: a single mode fiber having a core portion and a cladding portion for transmitting light; and a single mode fiber having a slightly larger inner diameter than the single mode fiber. The single mode fiber is used in a terminal for an optical device comprising: a capillary member held and fixed to an optical fiber by an adhesive; and a terminal body disposed coaxially with a core center of the single mode fiber and disposed on an outer periphery of the capillary member. The adhesive has a cutoff wavelength substantially equal to the wavelength, and a filler is mixed in the adhesive.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged sectional view of an optical device terminal according to a first embodiment of the present invention. Short single-mode fiber 1 having core and cladding
Is adhered and fixed to a capillary member 2 made of silicone resin or the like having a hole diameter of about 1 μm. Filler adhesive 3 for bonding and fixing is
An adhesive mixed with an inorganic filler such as alumina ceramic is used. The particle size of the inorganic filler is from 0.1 μm
About 0.5 μm is appropriate. A terminal 5 formed of metal or the like is provided on the outer periphery of the capillary member 2 so as to be coaxial with the center of the core of the single mode fiber 1.
The capillary member 2 and the terminal 5 are held and fixed by the adhesive 4. The size of the single-mode fiber 1, at the wavelength of light that is transmitted, as LP ₀₁ mode is a propagation mode of the single mode is substantially cut off,
The diameter of the core is determined.

In the optical device terminal shown in FIG. 1, an epoxy adhesive having a relatively large shrinkage force upon curing is suitable as the base of the adhesive 3 containing a filler. In general,
In the case where an inorganic filler is slightly mixed into these adhesives and the thickness of the adhesive layer is approximately the same as the particle size of the inorganic filler, the filler may be present on the bonding surface in places where the filler does not exist. When the filled adhesive 3 is cured, the shrinking force varies depending on the presence or absence of the filler, and the shrinking force of the filled adhesive 3 can be distributed in accordance with the distribution of the filler under the above-described bonding conditions. Therefore, the single-mode fiber 1 is added to the capillary member 2 by using the filler-containing adhesive 3 in which the inorganic filler is mixed in the base adhesive.
Is held and fixed, a random stress is applied in the axial direction of the single mode fiber 1 in accordance with the distribution of the filler. Cutoff wavelength near LP ₀₁ mode of the single mode fiber 1, when the confinement of light is weak, the external force such as bending the single mode fiber 1 is applied, easily passing the cladding portion. Therefore, due to the stress of the adhesive 3 containing the filler, the LP ₁₁ mode generated due to the misalignment with the other connected single mode fiber passes through the clad, and the LP ₀₁ mode and the L ₀₁ mode in the single mode fiber 1
The interference of P ₁₁ mode can be greatly reduced. Furthermore, LP ₀₁ mode is the propagation mode for strong confinement into the core, which propagates through the core of the single mode fiber 1 without attenuation.

Therefore, when this optical device terminal is used for an optical device, transmission loss is stabilized, and noise generated by the optical device during light transmission can be reduced.

FIG. 2 is a sectional view of a main part of an optical fixed attenuator according to a second embodiment of the present invention. Adhered to the capillary member 2 with the single-mode fiber filler-containing adhesive 3
Fixed. The capillary member 2 is adhesively fixed to the terminal 5. The terminal 5 has an inner periphery and an outer periphery formed by cutting or the like so as to be coaxial with the core center of the single mode fiber 1. A first end face 6 which is a light input / output end of the terminal 5 is optically polished so as to be connectable to an optical connector, and a second end face 7 which is another light input / output end. Are polished diagonally. A component composed of the single mode fiber 1, the adhesive 3 containing the filler of the capillary member 2, and the terminal 5, that is, two of the terminals for the optical device, were obliquely polished by the precision sleeve 10 provided on the outer periphery thereof. The end faces 7 are butted so as to face each other. The attenuating film 9 which is a light attenuator is sandwiched between the positions where the second end faces 7 abut each other. The main part of this optical fixed attenuator is 2
One end face 7 is fastened to an optical connector to form an optical fixed attenuator.

[0011]

As described above, the present invention provides an optical device terminal and another optical device by bonding a capillary member having a slightly larger inner diameter than a single fiber to a short single mode fiber with an adhesive containing a filler. the LP ₁₁ mode generated by the connection to be able to let escape the cladding of the single mode fiber.

[0012] As a result, the LP ₁₁ mode interference is LP ₀₁ mode and multimode, which is the original modes of propagation in the single mode fiber terminal for optical devices can be greatly reduced, thus the light of the optical device terminal When used in a device, there is an effect that transmission loss is stable and noise generated by the optical device during transmission can be reduced.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of an optical fixed attenuator according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single mode fiber 2 Capillary member 3 Filler adhesive 4 Adhesive 5 Terminal 6, 7 End face 9 Attenuation film 10 Precision sleeve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 6/10 G02B ^6/ 24-6/42

Claims (1)

(57) [Claims] A single-mode fiber having a core portion and a clad portion for transmitting light; a capillary member having a slightly larger inner diameter than the single-mode fiber and held and fixed to the single-mode fiber by an adhesive; In a terminal for an optical device comprising: a core center of the single mode fiber; and a terminal body disposed coaxially and on the outer periphery of the capillary member, the single mode fiber has a cutoff wavelength substantially equal to a wavelength used, and the adhesive A terminal for an optical device, characterized in that a terminal is mixed with a filler.