JPH0450810A - Photodiode module - Google Patents

Abstract

PURPOSE:To obtain the photodiode module low in distortion by providing a light shielding mask having a hole of a size of about the beam diameter radiated to a photodetecting area of a photodiode. CONSTITUTION:Light emitted from an optical fiber 1 is formed to parallel beams by radiating light condensed a little larger than the diameter of a hole 7a to a light shielding mask 7 having the hole 7a of a photodetecting part area or so of a photodiode chip 2 attached to the upper face of a glass window of the upper face of a cap by a selfoc lens 8, and the photodetecting part of the photodiode chip 2 is irradiated uniformly therewith. Accordingly, saturation of a photocurrent can be prevented, and also, it can be prevented that a reflected light by the photodetecting part of the photodiode chip 2 is reflected irregularly in the module, and radiated to other part than the photodetecting part of the photodiode chip 2. In such a way, a distortion of the photocurrent to an incident light output in eliminated, and a photodiode module low in distor tion can be obtained.

Description

[Detailed description of the invention] [Industrial field of application] The invention of Otsu is a photodiode (with low photocurrent distortion).
This relates to a Photo Diode (hereinafter abbreviated as PD) module.

[Conventional technology]

FIG. 3 is a cross-sectional view of a conventional PD module. In this figure, 1 is a single mode optical fiber that introduces light into the module, 2 is a PD chip that receives the light introduced from this single mode optical fiber 1, 3 is a heat sink that relieves the heat of this PD chip 2, and 4 5 is a stem for mounting the PD chip 2 and the heat sink 3; 5 is a cap for sealing the PD chip 2 and the heat sink 3; 6 is a stem for passing the light introduced from the single mode optical fiber 1 to the cap 5; The attached glass window 8 converts the light introduced from the single mode optical fiber 1 into a PD
a focusing lens for condensing light onto the light-receiving surface of the chip 2, 9
supports the single mode optical fiber 1 and the focusing lens 8, and supports the PD chip 2. Heat sink 3. Stem 4. This is a housing that holds a PD element, consisting of a cap 5° and a glass window 6.

FIG. 4 is a sectional view showing another conventional example of a PD module. In this figure, the same reference numerals as in FIG. The focus has been narrowed down to the light receiving section of the PD chip 2.

Next, the operation will be explained.

In the conventional PD module shown in Figs. 3 and 4, the PD
In order to prevent light from being applied to areas other than the light receiving part of chip 2,
5. Light emitted from the single mode optical fiber 1 is focused onto the light receiving portion of the PD chip 2 by a focusing lens 8.

This prevents deterioration in response characteristics due to irradiation of light onto areas other than the light receiving section.

[Problem to be solved by the invention]

In the conventional PD module as described above, the light emitted from the single mode optical fiber 1 is focused onto the light receiving section of the PD chip 2 by the focusing lens 8. Photocurrent is PD
It occurs on the part of Chitgo 2 that is irradiated with light on the light receiving part. Therefore, since the light is focused on the light receiving portion of the PD chip 2, the light density is saturated, and the photocurrent generated from the PD chip 2 is saturated. As a result, the photocurrent with respect to the incident light output loses linearity, causing distortion.

Also, since the light is condensed, it can be considered that light is reflected on the light receiving section of the PD chip 2. As a result, the light reflected on the light-receiving section of the PD chip 2 is diffusely reflected inside the module and irradiates a portion of the PD chip 2 other than the light-receiving section, causing leakage current and distortion.

As described above, the conventional PD module has a problem in that the photocurrent with respect to the output of the incident light is distorted by condensing the incident light.

This invention was made to solve the above-mentioned problems, and it prevents saturation of the photocurrent of the PD chip and
The purpose of this invention is to obtain a low-distortion photodiode module without distortion of photocurrent with respect to incident light output by preventing reflection of light on the light-receiving section of the D-chip.

[Means to solve the problem]

The photodiode module according to claim (1) of the present invention has a beam diameter approximately equal to the diameter of the beam irradiated onto the light receiving field of the photodiode, in order to uniformly irradiate the light receiving surface of the photodiode chip with an amount of light. It is equipped with a light-shielding mask with holes.

Further, the photodiode module according to claim (2) of the present invention is provided with a collimating lens that converts light into a parallel beam in order to uniformly irradiate the light receiving surface of the photodiode chip with an amount of light.

[Effect]

In the invention described in claim (1) of the present invention, a selfoc lens is used to pass the light emitted from the optical fiber into a hole about the size of the light receiving area of the photodiode chip attached to the top surface of the glass window on the top surface of the cap. By applying focused light slightly larger than the diameter of the hole to the light-shielding mask, it becomes a parallel beam, and by uniformly irradiating the light-receiving area of the photodiode chip, saturation of the photocurrent is prevented. By creating a thousand row beam, it is possible to prevent the reflected light from the light receiving part of the photodiode chip from being diffusely reflected within the module 9, and from irradiating parts other than the light receiving part of the photodiode chip, thereby preventing leakage current. can. This eliminates distortion of the photocurrent with respect to the incident light output.

In addition, in the invention described in claim (2), the light emitted from the optical fiber is made into a parallel beam in an area smaller than the light receiving area of the photodiode chip using a collimating lens, and the light is evenly distributed to the light receiving area. By irradiating the
Preventing the saturation of the photocurrent and making the light into a parallel beam prevents the reflected light from the light receiving area of the photodiode chip from leaking into the module and causing diffuse reflection, or from irradiating parts other than the light receiving area of the photodiode chip. This eliminates distortion of the photocurrent relative to the incident light output.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the same reference numerals as in FIGS. 3 and 4 indicate the same components, and 7 is a light receiving portion of the PD chip 2 for converting the light introduced from the single mode optical fiber 1 into a parallel beam. This is a light-shielding mask with a hole 7a of approximately the same area.

FIG. 2 is a sectional view of the structure of a PD module showing another embodiment of the present invention. In FIG. 2, the same reference numerals as in FIG. This is a Collineau 1-lens that makes the beam parallel to the other parts.

Next, the operation of the PD module shown in FIG. 1 will be explained.

The light emitted from the single mode optical fiber 1 is
A light-shielding mask 7 with a hole 7a about the area of the light-receiving part of the chip 2 is made, and a focusing lens 8 is used to condense light into a hole 7a slightly larger than the diameter of the hole 7a of the light-shielding mask 7, and the light is applied to the hole 7a of the light-shielding mask. The parallel beam is made so that the light that hits the light receiving part of the PD chip 2 is evenly irradiated. This results in
Since the reflection at the light receiving section of the PD chip 2 is less likely to be diffusely reflected within the module, light is not irradiated to areas other than the light receiving section, and no leakage current is generated. These can prevent the photocurrent from being distorted with respect to the incident light output.

The operation of the PD module shown in FIG. 2 is to collimate light introduced from a single optical fiber 1, convert it into a parallel beam using a second lens 10, and irradiate it onto the light receiving surface of the PD chip 2. The operation is similar to that shown in the figure.

〔Effect of the invention〕

As explained above, the invention described in claim (1) provides a hole having a size approximately equal to the diameter of the beam irradiated on the light receiving area of the photodiode, in order to uniformly irradiate the light amount on the light receiving surface of the photodiode chip. Since a light-shielding mask with an open area is provided, saturation of the photocurrent does not occur.

Furthermore, since the beam is made parallel, the light reflected at the light receiving section of the first diode chip is diffusely reflected inside the module, and the light is not irradiated to areas other than the light receiving section, thereby eliminating leakage current. This has the effect of eliminating distortion of photocurrent with respect to incident light output, and a photodiode module with low distortion can be obtained.

Furthermore, the invention as claimed in claim (2) is configured such that the light introduced from the single moto optical fiber is converted into a parallel beam by a collimating lens and irradiated onto the light receiving surface of the photodiode chip, so that saturation of the photocurrent is prevented. Does not occur. Also,
Since the beam is made parallel, the light reflected from the light receiving section of the photodiode chip is diffusely reflected inside the module, preventing light from being irradiated to areas other than the light receiving section, and leakage current is eliminated.

This has the effect of eliminating distortion of photocurrent with respect to incident light output, and a photodiode module with low distortion can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional side view showing the configuration of a PD module according to an embodiment of the present invention, FIG. 2 is a sectional side view of a PD module showing another embodiment of the invention, and FIGS. 3 and 4 are respectively FIG. 2 is a cross-sectional side view showing the configuration of a conventional PD module. In the figure, 1 is a single mode optical fiber, 2 is a PD
Chip, 3 is a heat sink, 4 is a stem, 5 is a cap, 6 is a glass window, 7 is a light shielding mask, 8 is a focusing lens,
9 is a housing, and 10 is a collimating lens. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent: Masuo Oiwa (2 others)

Claims (2)

[Claims] (1) In a photodiode module that obtains a photocurrent by irradiating light introduced from an optical fiber onto the light-receiving surface of a photodiode chip, in order to irradiate the light-receiving surface of the photodiode chip with an even amount of light, A photodiode module characterized in that a light-shielding mask is provided with a hole approximately the diameter of a beam irradiated onto a light-receiving area. (2) In a photodiode module that obtains a photocurrent by irradiating light introduced from an optical fiber onto the light-receiving surface of a photodiode chip, the light is parallelized in order to irradiate the light-receiving surface of the photodiode chip with an even amount of light. A photodiode module characterized by being provided with a collimating lens to form a shaped beam.