JPH09283776A - Light receiving unit - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a light receiving unit improved so that an optical signal can be efficiently received by a light receiving element. SOLUTION: A photodiode cap having an inner chamber in which a through hole is partially formed, a spherical ball lens fixed by closing the through hole, and arranged to face one of the ball lenses. A light receiving element and an optical fiber arranged opposite to the other ball lens while maintaining a predetermined optical size are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving unit for converting an optical signal transmitted via an optical fiber into an electric signal by a light receiving element, and in particular, has been improved so that the light signal can be efficiently received by the light receiving element. Regarding the light receiving unit.

[0002]

2. Description of the Related Art In a conventional light receiving unit, a photodiode is housed in a cap having a light receiving window portion made of flat glass, and the core diameter is large from the outside of the flat glass, for example, 0.4 mm diameter. The optical signal from the optical fiber is emitted to this photodiode.

[0003]

However, in the conventional light receiving unit as described above, when an optical signal from an optical fiber having a large core diameter is applied to the photodiode, the optical fiber end and the photodiode are separated from each other. There is a problem that the distance is restricted by the existence of the light receiving window portion and the entire amount of light cannot be received, which causes a decrease in efficiency.

[0004]

The present invention has, as a main structure for solving the above-mentioned problems, a photodiode cap having an inner chamber in which a through hole is partially formed, and the through hole is closed. Fixed spherical ball lens, and a light receiving element arranged facing one of the ball lenses,
The other of the above ball lenses is provided with an optical fiber arranged to face each other while maintaining a predetermined optical size.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the present invention. In this embodiment, the light receiving unit is attached to a printed circuit board.

Reference numeral 10 denotes a printed circuit board, and a peripheral portion of a cylindrical body 11 made of stainless steel or the like is fixed by sandwiching the printed circuit board 10 with a plurality of bolts 12 and 13.

The body 11 has a cylindrical recess 1 inside.
4 is formed, and the printed circuit board 10 of this recess 14 is formed.
A step portion 15 is formed with an inner diameter larger than the inner diameter of the recess 14 on the side fixed to

Further, a cylindrical coupling portion 17 is formed in the central portion of the bottom portion 16 of the body 11 so as to project to the outside thereof, and a screw portion 18 is formed in the periphery thereof. A concave portion 19 is formed inside the coupling portion 17 concentrically with the outer surface of the coupling portion 17, and a through hole 21 through which the optical fiber 20 penetrates is formed at the center thereof.

The screw portion 18 is screwed into the cap 22, and by rotating the cap 22, the guide 23 having an H-shaped cross section inside is pressed against the bottom surface of the recess 19. A through hole 24 is provided in the center of the guide 23, and an optical fiber 20 having a fixing member 25 that abuts the guide 23 is inserted and fixed therein.

The fixing member 25 is connected to the guide 23, and by rotating and fixing the cap 22, the position of the tip of the optical fiber 20 is elastically fixed by the function of the fixing member 25 and the position is determined. . 26 is optical fiber 2
A core wire of 0 and a ferrule 27 are made of, for example, ceramics.

A cylindrical photodiode cap 28 made of stainless steel or the like is inserted into the recess 14 of the body 11. A through hole 30 is formed in the center of the bottom portion 29 so as to face the core wire 26 of the optical fiber 20, and a ball lens 31 made of, for example, borosilicate crown glass is brazed into the through hole 30. It is fixed.

An edge 32 is formed on the open end side of the photodiode cap 28 so as to be widened outward. The edge 32 is fixed in close contact with the step 15 of the body 11. There is. The heat generated in the photodiode cap 28 by this tight fixing is radiated to the outside through the body 11.

Further, the open end of the photodiode cap 28 is hermetically closed by a hermetic terminal 34 to which a lead wire for guiding a signal to the outside or a lead wire group 33a to 33e for introducing a current from the outside is fixed. It is fixed to.

In the photodiode cap 28,
The photo diode 3 is arranged so as to face the ball lens 31.
The case 36 to which 5 is fixed is fixed, and the case 36
Although not shown in the figure, a Peltier element and a thermistor element are built in so that the operating temperature can be cooled to a predetermined temperature by the current transmitted from the lead wire groups 33a to 33e.

As the photodiode 35, for example, a GaInAs PIN photodiode having a high sensitivity in the near infrared wavelength range is used, and the dark current of the photodiode 35 is greatly reduced by adjusting the temperature to a predetermined temperature by a Peltier element. I am letting you. The thermistor element functions as a sensor for controlling the temperature to a predetermined temperature.

As described above, the light emitted from the optical fiber 20 to the ball lens 31 is refracted by the ball lens 31, condensed and applied to the photodiode 35.
The amount of light received can be greatly increased, which is effective in improving sensitivity.

The body 11 is attached to the outer surface of the photodiode cap 28 as a reference, and the guide 2
3. Since the optical fiber 20 is elastically brought into contact with the photodiode cap 28 via the fixing member 25, the optical dimensions can be accurately maintained.

Further, since the edge portion 32 of the photodiode cap 28 and the step portion 15 of the body 11 are fixed in close contact with each other, the heat generated in the photodiode cap 28 can be easily transferred to the outside through the body 11. Can dissipate heat.

[0019]

As described above in detail with the embodiment of the invention, according to the invention described in claim 1, the optical signal is emitted from the optical fiber to the ball lens and collected by the ball lens 31. Since the photo diode 35 is configured to emit light and irradiate the photo diode 35, it is possible to significantly increase the amount of received light, which is effective in improving sensitivity.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, it is possible to easily radiate the heat generated inside the photodiode to the outside. There is.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention.

[Explanation of symbols]

 10 Printed Circuit Board 11 Body 15 Step 20 Optical Fiber 22 Cap 23 Guide 26 Core Wire 28 Diode Cap 31 Ball Lens 32 Edge 34 Hermetic Terminal 35 Photodiode

Claims (2)

[Claims] 1. A photodiode cap having an inner chamber partially formed with a through hole, a spherical ball lens fixed by closing the through hole, and arranged to face one of the ball lenses. A light receiving unit comprising: a light receiving element; and an optical fiber arranged opposite to the other of the ball lenses while maintaining a predetermined optical size. 2. A body for accommodating the photodiode cap therein, wherein an edge portion provided on the open end side of the photodiode cap and the body are combined to generate inside the photodiode cap. The light receiving unit according to claim 1, wherein heat is radiated.