JP2004325562A - Light signal receiving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light signal receiving apparatus which provides a wide dynamic range without increasing the size and which can respond to a wide range of application. <P>SOLUTION: A glass plate 5 having a light controlling and filtering effect is disposed in the optical path of the light signal exiting from the exit end face of a fiber ferule 10 which houses an optical fiber to a light receiving element which receives the signal. Thereby, the light is received after a component of the light signal at specified intensity or higher is attenuated. This enlarges the dynamic range and the apparatus can be used for a wide range of application. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical signal receiving device, and is particularly suitable for a device incorporating a transimpedance amplifier.
[0002]
[Prior art]
FIG. 12 shows a side sectional structure of an optical system of a conventional optical signal receiving apparatus with a built-in transimpedance amplifier.
[0003]
A substrate 2 is housed in a package 1, a transimpedance amplifier 3 is mounted on the substrate 2, and is electrically connected to a carrier 4.
[0004]
A light receiving element 5 is mounted on the surface of the carrier 4, and incident light passing through the glass plate 6 of the package 1 is received by the light receiving element 5.
[0005]
On the other hand, a lens holder 7 is coupled to the package 1, and a lens 8 is housed in the lens holder 7. A ferrule holder 9 is coupled to the lens holder 7, a fiber ferrule 10 is stored in the ferrule holder 9, and an optical fiber (not shown) is stored in the fiber ferrule 10, and an optical signal is transmitted. You.
[0006]
The optical signal 11 emitted from the end face of the fiber ferrule 10 is collected by the lens 8, passes through the glass plate 6, and enters the light receiving element 5.
[0007]
The incident optical signal 11 is converted from an optical signal into an electric signal by the light receiving element 5, amplified by the transimpedance amplifier 3, and output.
[0008]
FIG. 13 shows the relationship between the input current of the transimpedance amplifier 3 and the amplitude of the output signal. Further, the eye pattern data at points A, B and C shown in FIG. 13 are shown in FIGS. 14 (a), (b) and (c), respectively.
[0009]
As shown at point C in FIG. 13, when the input current exceeds a predetermined value (for example, 1200 μA), the transimpedance amplifier 3 saturates and an eye opening cannot be obtained as shown in FIG. In a region where the input current value is larger than the value, the bit error rate characteristic deteriorates (maximum receiving sensitivity characteristic: Po).
[0010]
Further, even in a region where the input signal value is too small, an eye opening cannot be obtained due to noise, and the code error rate characteristic deteriorates (minimum receiving sensitivity: Ps).
[0011]
Due to such input / output characteristics of the transimpedance amplifier 3, a region (dynamic range) where the maximum receiving sensitivity and the minimum receiving sensitivity are obtained in the bit error rate characteristics of the receiving device is determined.
[0012]
FIG. 15 shows the input electric signal level with respect to the input optical signal level of the PD module when the transimpedance amplifier 3 having the light receiving sensitivity of 0.8 (A / W) and having the input / output characteristics shown in FIG. The line L12 shows an example of the output amplitude of the transimpedance amplifier 3 with respect to the input optical signal level.
[0013]
As described with reference to FIGS. 13 and 14A to 14C, the maximum reception sensitivity and the minimum reception sensitivity are largely determined by the input / output characteristics of the transimpedance amplifier 3.
[0014]
Here, assuming that the input electric signal level when the maximum reception sensitivity Po is obtained is 1200 μA and the output amplitude of the transimpedance amplifier 3 is 25 Vp-p when the minimum reception sensitivity Ps is obtained, the PD module shown in FIG. The maximum reception sensitivity in the error rate characteristic of (1) is +1.5 dBm, the minimum reception sensitivity is -17.5 dBm, and the dynamic range of this PD module is 19.0 dB.
[0015]
The input electric signal level with respect to the input optical signal level of the APD module using the transimpedance amplifier 3 having the input / output characteristics shown in FIG. 15 with the light receiving sensitivity of 0.8 A / W and the multiplication factor M = 9 is shown by a line L13 in FIG. And an example of the output amplitude of the transimpedance amplifier 3 is shown as a line L14.
[0016]
In this case, in FIG. 16, the maximum reception sensitivity of the error rate characteristic of the APD module is −7.5 dBm, the minimum reception sensitivity is −26.5 dBm, and the dynamic range of this APD module is 19.0 dB.
[0017]
With respect to the APD module, when the input optical signal level is large, the maximum reception sensitivity of -4 dBm can be obtained by lowering the multiplication factor, and the dynamic range becomes 22.5 dB.
[0018]
Documents disclosing the conventional optical receiving module are shown below.
[0019]
[Patent Document 1]
JP-A-11-168431 [Patent Document 2]
Japanese Patent Application Laid-Open No. H11-26083 [Patent Document 3]
Japanese Patent Application Laid-Open No. 2002-261300 [Patent Document 4]
JP 2002-269895 A
[Problems to be solved by the invention]
However, in the conventional optical signal receiving apparatus as described above, the dynamic range is narrow, so it is necessary to use different modules depending on the application, such as for short-range communication and long-distance communication. could not.
[0021]
The present invention has been made in view of the above circumstances, and has as its object to provide an optical signal receiving apparatus that can obtain a wide dynamic range without increasing the size and can support a wide range of applications.
[0022]
[Means for Solving the Problems]
The optical signal receiving device of the present invention includes:
An optical fiber that transmits an optical signal and exits from the exit end face;
A light-receiving element that receives the emitted optical signal and converts it into an electric signal;
An amplifier which receives the electric signal, amplifies and outputs the electric signal,
A dimming glass plate provided in an optical path until the optical signal emitted from the emission end face of the optical fiber is received by the light receiving element, and having a dimming function of attenuating the optical signal as the light intensity increases. And characterized in that:
[0023]
Alternatively, the optical signal receiving device of the present invention
An optical fiber that transmits an optical signal and exits from the exit end face;
A light-receiving element that receives the emitted optical signal and converts it into an electric signal;
An amplifier which receives the electric signal, amplifies and outputs the electric signal,
A light control filter provided in an optical path until the optical signal emitted from the emission end face of the optical fiber is received by the light receiving element, and attenuating the optical signal as light intensity increases. And
[0024]
Here, it is preferable that at least two light control filters are provided in the optical path.
[0025]
The light control filter may be a light control filter film provided on a surface of a glass plate provided in the optical path, and at least two light control filter films may be laminated.
[0026]
The optical path may further include a lens for condensing the optical signal and causing the light receiving element to receive the light signal, and the dimming filter may be a dimming filter film provided on a surface of the lens.
[0027]
The light control filter may be a light control filter film provided on an emission end face of the optical fiber.
[0028]
The light control filter may be a light control filter film provided on a surface of the light receiving element.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0030]
(1) First Embodiment An optical signal receiving apparatus according to a first embodiment of the present invention has a sectional configuration shown in FIG.
[0031]
In this optical signal receiving device, a substrate 2 is housed in a package 1, a transimpedance amplifier 3 is mounted on the substrate 2, and is electrically connected to a carrier 4.
[0032]
The light receiving element 5 is mounted on the surface of the carrier 4, and the incident light passing through the dimming filter glass plate 106 of the package 1 is received by the light receiving element 5.
[0033]
On the other hand, a lens holder 7 is coupled to the package 1, and a lens 8 is housed in the lens holder 7. A ferrule holder 9 is coupled to the lens holder 7, a fiber ferrule 10 is stored in the ferrule holder 9, and an optical fiber (not shown) is stored in the fiber ferrule 10, and an optical signal is transmitted. You.
[0034]
The optical signal 11 emitted from the end face of the fiber ferrule 10 is condensed by the lens 8, passes through the dimming filter glass plate 106, and enters the light receiving element 5. The incident optical signal 11 is converted from an optical signal into an electric signal by the light receiving element 5, amplified by the transimpedance amplifier 3, and output.
[0035]
Here, as compared with the conventional apparatus, the present embodiment is characterized in that the glass plate is replaced with a light control filter glass plate 106. The dimming filter glass plate 106 has a function as a dimming filter that changes the color and the degree of light absorption due to fluctuations in light intensity. A material obtained by evaporating a material such as reflective chrome on the surface can be used.
[0036]
By providing such a dimming filter glass plate 106, after the optical signal 11 emitted from the emission end face of the fiber ferrule 10 is condensed by the lens 8, the predetermined level of the optical signal 11 is obtained by the dimming filter glass 106. After the light intensity is attenuated in the above components, the light is received by the light receiving element 5 and converted into an electric signal, and then input to the transimpedance amplifier.
[0037]
FIG. 2 shows an example of a change in transmittance with respect to a change in light intensity (input optical signal level) in the light control filter glass plate 106, as indicated by a line L1. It can be seen that the transmittance decreases as the light intensity increases. In this case, the optical signal level after transmission with respect to the input optical signal level is as shown by the line L2.
[0038]
The input electric signal level with respect to the input optical signal level of the APD module when the dimming filter glass plate 106 having the characteristics shown in FIG. 2 is used is shown by a line L3 in FIG. 3, and the transimpedance amplifier 3 with respect to the input optical signal level is shown. An example of the output amplitude is shown by line L4.
[0039]
Compared with the conventional device shown in FIG. 16, the maximum receiving sensitivity is improved by 1.0 dB from -7.5 dBm to -6.5 dBm, and the dynamic range is expanded from 19.0 dB to 20 dB.
[0040]
Also, by lowering the multiplication factor when the input optical signal level is high, the maximum receiving sensitivity becomes +2 dBm and the dynamic range becomes 28.5 dB.
[0041]
In the case of the PD module, the maximum receiving sensitivity is +7.5 dBm, the minimum receiving sensitivity is -17 dBm, and the dynamic range is 24.5 dB.
[0042]
(2) Second Embodiment An optical signal receiving apparatus according to a second embodiment of the present invention will be described.
[0043]
The second embodiment has the configuration shown in FIG. 4, and is different from the first embodiment in that both surfaces of the glass plate 206 on the incident light side and on the outgoing light side have dimming. The difference is that a filter film 201 is provided. The light control filter film 201 has a function of changing the color and the degree of light absorption by a change in light intensity, similarly to the light control filter glass plate 106 in the first embodiment.
[0044]
By providing the glass plate 206 on which the light control filter film 201 is provided, the optical signal 11 emitted from the output end of the fiber ferrule 10 is condensed by the lens 8, and then the light is output by the light control filter film 201. The light intensity is attenuated in a component of the signal 11 that is equal to or higher than a predetermined level.
[0045]
Here, in this embodiment, since the light passes through the dimming filter film 201 provided on both surfaces of the glass plate 206, the light passes through the dimming filter film twice, and the optical signal 11 received by the light receiving element 5 becomes , Is greatly attenuated as compared with the first embodiment.
[0046]
FIG. 5 shows an example of an input optical signal level to the light control filter film 201 and an optical signal level after transmission after passing through the light control filter film 201.
[0047]
In the case of the PD module, the maximum receiving sensitivity is +13.5 dBm, the minimum receiving sensitivity is -17 dBm, and the dynamic range is 30.5 dB.
[0048]
On the other hand, in the case of the APD module, the maximum receiving sensitivity is -5.5 dBm, the minimum receiving sensitivity is -26.5 dBm, and the dynamic range is 21 dB.
[0049]
Further, when the input optical signal level is large, by decreasing the multiplication factor, a maximum reception sensitivity of +8 dBm can be obtained, and the dynamic range is further expanded to 34.5 dB.
[0050]
(3) Third Embodiment A third embodiment of the present invention will be described with reference to FIG.
[0051]
The present embodiment is characterized in that a dimming filter film 301 is provided on the surface on the incident light side and the surface on the output light side of the lens 308, that is, on both surfaces. The dimming filter film 301 has the function of changing the color and the degree of light absorption by the light intensity fluctuation, similarly to the dimming filter film 201 in the second embodiment.
[0052]
By providing the lens 308 provided with such a dimming filter film 301, the optical signal 11 emitted from the emission end of the fiber ferrule 10 is first collected by the lens 308 and after the light signal 11 is collected. The light intensity of the component of the optical signal 11 twice or more attenuated by the dimming filter film 301 is attenuated, received by the light receiving element 5 and converted into an electric signal, and then input to the transimpedance amplifier.
[0053]
As described above, in this embodiment, since the light passes through the light control filter film 301 provided on both surfaces of the lens 306, the light signal 11 received by the light receiving element 5 passes through the light control filter film twice, , As in the second embodiment, it is greatly attenuated compared to the first embodiment.
[0054]
Therefore, in the present embodiment, a wide dynamic range can be obtained as in the second embodiment.
[0055]
(4) Fourth Embodiment A fourth embodiment of the present invention will be described with reference to the drawings.
[0056]
This embodiment is characterized in that a dimming filter film 401 is provided on the light emitting end face of the fiber ferrule 410 as shown in FIG. Like the light control filter film 201 in the second embodiment and the light control filter film 301 in the third embodiment, the light control filter film 401 has a color or light absorption degree due to light intensity fluctuation. Has the effect of changing
[0057]
By providing such a dimming filter film 401 with the fiber ferrule 410 provided on the output end face, when the light is emitted from the output end of the fiber ferrule 410, the light intensity of a component equal to or higher than a predetermined level is attenuated, and the optical signal After the light 11 is condensed by the lens 308, the light 11 is received by the light receiving element 5, converted into an electric signal, and input to the transimpedance amplifier.
[0058]
In the present embodiment, it is possible to obtain a dynamic range substantially equal to that of the first embodiment.
[0059]
(5) Fifth Embodiment A fifth embodiment of the present invention will be described with reference to FIG.
[0060]
The present embodiment is characterized in that a light control filter film 501 is provided on a light receiving surface of a light receiving element 505. The light control filter film 501 has an effect of changing the color and the degree of light absorption by the light intensity fluctuation, similarly to the light control filter film 401 in the fourth embodiment.
[0061]
By providing such a light control filter film 501 with the light receiving element 505 provided on the light receiving surface, the optical signal 11 emitted from the end face of the fiber ferrule 10 is condensed by the lens 8 and passes through the glass plate 6. The light is received in an attenuated state by the dimming filter film 501 applied to the light receiving surface of the light receiving element 505, converted into an electric signal, and input to the transimpedance amplifier 3.
[0062]
In the present embodiment, it is possible to obtain a dynamic range substantially equal to that of the first embodiment.
[0063]
(6) Sixth Embodiment A sixth embodiment of the present invention will be described with reference to FIG.
[0064]
In the present embodiment, like the second embodiment, the dimming filter films 602 and 603 are formed on both surfaces of the glass plate 606, and the light adjusting filter films 602 and 603 are formed on the emission end face of the fiber ferrule 610 as in the fourth embodiment. The optical filter film 604 is provided with a dimming filter film 601 on the light receiving surface of the light receiving element 605 similarly to the fifth embodiment.
[0065]
These dimming filter films 601 to 604 have an effect of changing the color and the degree of light absorption by the light intensity fluctuation.
[0066]
As described above, according to the present embodiment, light is attenuated four times by the dimming filter films 601 to 604, so that a wider dynamic range can be obtained than in the first to fifth embodiments. it can.
[0067]
(7) Seventh Embodiment A seventh embodiment of the present invention has the configuration shown in FIG.
[0068]
The present embodiment corresponds to a configuration in which two light control filter glass plates in the first embodiment are provided in series on the optical path.
[0069]
As a result, the optical signal 11 emitted from the end face of the fiber ferrule 10 is condensed by the lens 8, passes through the two dimming filter glass plates 701 and 702, and enters the light receiving element 5. The optical signal is converted into an electric signal, and is output after being amplified by the transimpedance amplifier 3.
[0070]
According to the present embodiment, light is attenuated twice by the dimming filter glass plates 701 and 702, so that it is possible to obtain a wide dynamic range almost equivalent to that of the second and third embodiments. it can.
[0071]
(8) Eighth Embodiment An eighth embodiment of the present invention will be described with reference to FIG.
[0072]
This embodiment is equivalent to the above-described second embodiment shown in FIG. 4 in which the dimming filter films 201 provided on both surfaces of the glass plate 206 have a laminated structure of two or more layers. . The other configuration is the same as that of the second embodiment, and the description is omitted.
[0073]
FIG. 11 shows an example in which the light control filter film 201 has a laminated structure. At least two layers of dimming filter films are laminated on both surfaces of the glass plate 206, and here, three layers of dimming filter films 801, 802, 803 are laminated.
[0074]
By using such a glass plate 206, an optical signal is attenuated a plurality of times on both surfaces of the glass plate 206, so that a wider dynamic range can be obtained than in the second embodiment.
[0075]
【The invention's effect】
As described above, according to the optical signal receiving apparatus of the present invention, a component equal to or higher than a predetermined level is attenuated by the dimming filter film in any one of the optical paths through which the optical signal passes, and is equivalent to the conventional apparatus. Since the width of the dynamic range can be further expanded with the size of, it can be used for a wide range of applications from short-range communication to long-range communication.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a configuration of an optical signal receiving device according to a first embodiment of the present invention.
FIG. 2 is a graph showing an example of a change in transmittance with respect to a change in light intensity in the dimming filter glass plate, and an optical signal level after transmission with respect to an input optical signal level in the first embodiment.
FIG. 3 shows an example of an input electric signal level with respect to an input optical signal level of the APD module and an output amplitude of a transimpedance amplifier with respect to the input optical signal level when a dimming filter glass plate having the characteristics shown in FIG. 2 is used. A graph showing.
FIG. 4 is a longitudinal sectional view showing a configuration of an optical signal receiving device according to a second embodiment of the present invention.
FIG. 5 is a graph showing the level of an optical signal after transmission with respect to an input optical signal in the second embodiment.
FIG. 6 is a longitudinal sectional view showing a configuration of an optical signal receiving device according to a third embodiment of the present invention.
FIG. 7 is a longitudinal sectional view showing a configuration of an optical signal receiving device according to a fourth embodiment of the present invention.
FIG. 8 is a longitudinal sectional view showing a configuration of an optical signal receiving device according to a fifth embodiment of the present invention.
FIG. 9 is a longitudinal sectional view showing a configuration of an optical signal receiving device according to a sixth embodiment of the present invention.
FIG. 10 is a longitudinal sectional view showing a configuration of an optical signal receiving device according to a seventh embodiment of the present invention.
FIG. 11 is a longitudinal sectional view showing a configuration of an optical signal receiving device according to an eighth embodiment of the present invention.
FIG. 12 is a longitudinal sectional view showing a configuration of a conventional optical signal receiving device.
FIG. 13 is a graph showing input / output characteristics of a transimpedance amplifier used in an optical signal receiving apparatus to which the present invention can be applied.
FIG. 14 is an explanatory diagram showing eye pattern data at points A, B, and C in FIG. 13;
FIG. 15 is a graph showing a relationship between an input electric signal level and an output amplitude of a transimpedance amplifier with respect to an input optical signal level in a PD module.
FIG. 16 is a graph showing a relationship between an input electric signal level and an output amplitude of a transimpedance amplifier with respect to an input optical signal level in the APD module.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Package 2 Substrate 3 Transimpedance amplifier 4 Carrier 5, 505, 605 Light receiving element 6, 206 Glass plate 7 Lens holder 8, 308 Lens 9 Ferrule holder 10, 410, 610 Fiber ferrule 11 Optical signal 106 Dimming filter glass plate 201 301, 401, 501, 601 to 604, 701 to 702, 801 to 803

Claims (8)

In the optical signal receiving device,
An optical fiber that transmits an optical signal and exits from the exit end face;
A light-receiving element that receives the emitted optical signal and converts it into an electric signal;
An amplifier which receives the electric signal, amplifies and outputs the electric signal,
A dimming glass plate provided in an optical path until the optical signal emitted from the emission end face of the optical fiber is received by the light receiving element, and having a dimming function of attenuating the optical signal as the light intensity increases. When,
An optical signal receiving device comprising: In the optical signal receiving device,
An optical fiber that transmits an optical signal and exits from the exit end face;
A light-receiving element that receives the emitted optical signal and converts it into an electric signal;
An amplifier which receives the electric signal, amplifies and outputs the electric signal,
A light control filter that is provided in an optical path until the optical signal emitted from the emission end face of the optical fiber is received by the light receiving element, and attenuates the optical signal as light intensity increases,
An optical signal receiving device comprising: 3. The optical signal receiving device according to claim 2, wherein at least two dimming filters are provided in the optical path. The optical signal receiving device according to claim 2, wherein the light control filter is a light control filter film provided on a surface of a glass plate provided in the optical path. The optical signal receiving device according to claim 4, wherein the dimming filter films provided on the surface of the glass are laminated in at least two layers. In the optical path, further comprises a lens for condensing the optical signal and causing the light receiving element to receive light,
The optical signal receiving device according to claim 2, wherein the light control filter is a light control filter film provided on a surface of the lens. 3. The optical signal receiving device according to claim 2, wherein the dimming filter is a dimming filter film provided on an emission end face of the optical fiber. The optical signal receiving device according to claim 2, wherein the light control filter is a light control filter film provided on a surface of the light receiving element.

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