JPS6217621A - Optical power meter - Google Patents

Abstract

PURPOSE:To enable the effective temp. compensation of the measuring error of optical power, by correcting the value of optical power on the basis of the temp. detection signal corresponding to the change in the temp. of a photoelectric converter element. CONSTITUTION:The transmission optical signal of an optical fiber 2 is received by the photodiode 6 of a light receiving part 4 to be converted to an electric signal which is, in turn, inputted to a control circuit 26 through an amplifier 12 and an A/D converter 16. The circumferential temp. of the photodiode 6 is detected by a temp. sensor 8 to output the corresponding temp. detection signal which is, in turn, inputted to the circuit 26 through an amplifier 14 and an A/D converter 18. The circuit 26 calculates the optical power of an incident optical signal from the quantity-of-light information of the photodiode 6 and the wavelength information of a wavelength setting switch 22 and subsequently reads the temp. characteristic data of an incident light wavelength and detection sensitivity from a memory 20 on the basis of the temp. information of the sensor 8 and the wavelength information of the switch 22 to perform the temp. correction of optical power.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an optical power meter used for measuring optical power.

(b) Prior art and its problems In general, in the field of optical communications, optical power meters are used to measure the transmission loss of transmitted optical signals in optical fibers, the transmission characteristics of optical signals, etc. . The light receiving section of this optical power meter is provided with a photoelectric conversion element such as a photodiode.

By the way, there are various types of photodiodes that are widely used as the above-mentioned photoelectric conversion elements, such as silicon photodiodes and germanium photodiodes. It has a positive temperature coefficient on the short wavelength side and a negative temperature coefficient on the short wavelength side. For this reason, depending on the wavelength of the received optical signal, the sensitivity of the photodiode changes by several percent to several tens of percent as the temperature changes.

However, conventional optical power meters do not take into account the temperature characteristics of the photodetection sensitivity of the photoelectric conversion element, and therefore, depending on the ambient temperature of the light receiving part and the wavelength of the incident optical signal, the measurement There are problems such as a large error may occur in the optical power output.

The present invention has been developed in view of these circumstances.7)7) Effectively compensates for measurement errors in light intensity caused by temperature changes in a light receiving section having a charge conversion element.

The purpose is to make it possible to

(C) Means for Solving the Problems In order to achieve the above object, the present invention provides a light receiving section provided with a photoelectric conversion element that photoelectrically converts an optical signal, and the optical signal received by the light receiving section. and a device main body for measuring the value of optical power from the photoelectric conversion element, wherein the light receiving section is provided with a temperature detection means for outputting a temperature detection signal corresponding to a temperature change of the photoelectric conversion element; The main body of the apparatus is provided with temperature correction means for correcting the value of the optical power based on the temperature detection signal detected by the temperature detection means.

(d) Effect In the above configuration, when the ambient temperature of the photoelectric conversion element provided in the light receiving section changes, the temperature detection means outputs a temperature detection signal corresponding to the temperature change. Then, this temperature detection signal can be used to determine the temperature hli on the main body side.

The temperature correction means temperature-corrects the optical power based on the value of the temperature detection signal from the temperature detection means.

(e) Examples Hereinafter, the present invention will be explained in detail based on examples shown in the drawings.

Embodiment 1 FIG. 1 is a block diagram of an optical power meter according to an embodiment of the present invention. In the figure, ■ indicates the entire optical power meter, 2 is the optical fiber through which the optical signal to be measured is transmitted, and 4 is the light receiving part that receives the optical signal transmitted via the optical fiber 2. be.

The light receiving section 4 includes a photodiode 6 as a photoelectric conversion element that photoelectrically converts an optical signal, and a temperature detection means that is located close to the photodiode 6 and outputs a temperature detection signal corresponding to a temperature change of the photodiode. Temperature sensor 8
is provided.

Reference numeral 10 is a device main body that measures the optical power of the optical signal to be measured transmitted through the optical fiber 2. Reference numeral 12 is a first unit that amplifies the signal photoelectrically converted by the photodiode 6.
An amplifier, 14 is a second amplifier that amplifies the temperature detection signal from the temperature sensor 8, 16 is a first A/D converter that digitizes the signal amplified by the first amplifier 12, and 18 is amplified by the second amplifier 14. This is a second A/D converter that digitizes the detected temperature detection signal. 20 is a temperature characteristic data memory in which temperature characteristic data of the light detection sensitivity of the photodiode 6 is stored in advance; 22 is a wavelength setting switch for inputting wavelength information of the optical signal incident on the photodiode 6; and 24 is an ink face. . 26 calculates the optical power of the incident optical signal from the light amount information of the optical signal received by the photodiode 6 and the wavelength information from the wavelength setting switch 22;
Furthermore, it is a control circuit that temperature-corrects the optical power calculated based on the temperature sensor 8 and the temperature characteristic data from the temperature characteristic data memory 20. In this example, the temperature characteristic data memory 20 and the control circuit 26 make up the temperature correction means 28.
is configured. 30 is a display circuit for displaying the temperature-corrected optical power value, and 32 is a light emitting diode for numerical display.

In the optical power meter 1 having such a configuration, an optical signal transmitted from the optical fiber 2 is received by the photodiode 6 of the light receiving section 4 and converted into an electrical signal. This signal is input to the control circuit 26 via the first amplifier 12 and the first A/D converter 16. Furthermore, since the wavelength of the optical signal to be measured is known in advance, when the wavelength of this optical signal is set with the wavelength setting switch 22, this wavelength information is input to the control circuit 26 via the interface 24.

On the other hand, the ambient temperature of the photodiode 6 is detected by a temperature sensor 8, and the temperature sensor 8 outputs a temperature detection signal corresponding to the detected temperature. The temperature detection signal is then passed through the second amplifier 14 and the second A/D converter 18 to the control circuit 26.
is input. The control circuit 26 calculates the optical power of the input optical signal from the scene information of the optical signal received by the photodiode 6 and the wavelength information from the wavelength setting switch 22 .

Next, the control circuit 26 generates a temperature characteristic data memo IJ 20 based on the temperature information from the temperature sensor 8 and the wavelength information from the wavelength setting switch 22. The temperature characteristic data of the detection sensitivity is read out, and the previously calculated optical power is temperature-corrected based on this temperature characteristic data. Then, since the temperature-corrected optical power data is given to the display circuit 30, the light emitting diode 32 lights up and the value of the optical power is displayed numerically.

'(ヱ(ζ) FIG. 2 is a block diagram of the optical power meter according to this embodiment. In the figure, 50 indicates the entire optical power meter, 52 indicates the optical fiber, and 54 indicates the optical fiber 2. The light receiving unit 54 is provided with a photodiode 56 as a photoelectric conversion element that photoelectrically converts the optical signal. Temperature detection means 58 is attached to output a temperature detection signal corresponding to the temperature detection signal.

The L-foot temperature detection means 58 includes a plurality of output stabilized light sources 60a to 60n having different wavelengths, and one output stabilized light source 60 selected according to the wavelength of the optical signal to be measured.
A temperature correction optical fiber 62 that guides light from a to 60n to the photodiode 56, and both optical fibers 52 and 62.
The photodiode 56 includes a light shielding plate 64 that is slidably provided on the front surface of the light receiving side of the photodiode 56 in order to select light from the photodiode 56 .

Reference numeral 66 denotes a device main body that measures the optical power of the optical signal to be measured that has been transmitted through the optical fiber 52. 68 is an amplifier that amplifies the signal photoelectrically converted by the photodiode 56; 70 is a changeover switch that switches the connection between when receiving the optical signal to be measured and when receiving the light from the temperature correction optical fiber 62; 72 is a first A/D converter that digitizes the signal obtained when receiving the optical signal to be measured, and 74 digitizes the signal obtained when receiving the light from the temperature correction optical fiber 62. A second A/D converter for digitizing.

76 is a temperature characteristic data memory of the photodetection sensitivity of the photodiode 56, which outputs the stabilized light source 6 under the temperature at the time of measurement.
Temperature characteristic data of the photodetection sensitivity of the photodiode 56 is sent to a control circuit 82 (described later) in correspondence with the output when the photodiode 56 receives light from 0a to 60n and the wavelength of the output stabilized light source 60a to 60n.

78 is a wavelength setting switch for inputting wavelength information of an optical signal to be measured, and 80 is an interface. 82 calculates the optical power of the optical signal to be measured based on the optical signal to be measured received by the photodiode 56 and the wavelength information from the wavelength setting switch 78; This is a control circuit that temperature-corrects the optical power based on the temperature characteristic data read out from the temperature characteristic data memory 76. In this example, the temperature characteristic data memory 76 and the control circuit 82 constitute a temperature correction means 84. 86 is a display circuit for displaying the temperature-corrected optical power value, and 88 is a light emitting diode for numerical display.

In the optical power meter 50 having such a configuration, an optical signal to be measured transmitted from the optical fiber 52 is received by the photodiode 56 of the light receiving section 54 and converted into an electrical signal. This signal is passed through an amplifier 68, a selector switch 70. The first A/D converter 72 is sequentially operated and input to the control circuit 82 .

Furthermore, since the wavelength of the optical signal transmitted through the optical fiber 2 is known in advance, when the wavelength of this optical signal is set with the wavelength setting switch 78, this wavelength information is input to the control circuit 82 via the interface 80. be done.

On the other hand, from among the plurality of output stabilized light sources 60a to 60n, an output stabilized light source, for example 60a, which emits light that most closely approximates the wavelength of the optical signal to be measured is selected, and light from this output stabilized light source 60a is selected. is guided to the photodiode 56 via the optical fiber 62 for warm correction. In this state, the light shielding plate 6
4 is slid between both optical fibers 52, 62 and the photodiode 56, the optical signal from the optical fiber 52 to be measured and the light from the output stabilized light source 60a are alternately or randomly transmitted. is incident on the photodiode 56. When the photodiode 56 receives light from the output stabilized light source 60a, its output value changes in response to changes in ambient temperature. In this case, the output signal from the photodiode 56 is sent to the amplifier 68 as a temperature detection signal.
, the changeover switch 70, and the second A/D converter 74 in order. When the temperature detection signal is input, the control circuit 82 immediately reads out the temperature characteristic data of the light detection sensitivity of the photodiode 56 corresponding to the wavelength of the temperature stabilized light source 60a from the temperature characteristic data memory 76.

Next, the control circuit 82 calculates the optical power of the optical signal based on the light amount information of the optical signal transmitted through the optical fiber 52 and the wavelength information given from the wavelength setting switch 78. Subsequently, the control circuit 82 selects light having the wavelength of the light currently incident on the photodiode 56 from the temperature characteristic data memory 76 based on the temperature information from the temperature detection means 1 58 and the wavelength information from the wavelength setting switch 78. The temperature characteristic data of the detection sensitivity is read out, and the previously calculated optical power is temperature-corrected based on this temperature characteristic data. Then, since the temperature-corrected optical power data is given to the display circuit 86, the light emitting diode 88 lights up and the temperature-corrected optical power value is displayed numerically.

Note that since the dark current of the photodiode has a positive temperature coefficient, it increases even more as the temperature rises, but temperature compensation for this dark current is also possible by applying the present invention.

(F) Effect As described above, according to the present invention, when the temperature of a photoelectric conversion element such as a photodiode changes, a temperature detection signal is output from the temperature detection means, so the temperature is determined based on the value of this temperature detection signal. A correction means temperature-corrects the optical power of the optical signal. Therefore, it becomes possible to effectively compensate for the measurement error in optical power due to temperature changes in the photoelectric conversion element.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 shows embodiment 1.
FIG. 2 is a block diagram of an optical power meter corresponding to the second embodiment. 1.50... Optical power meter, 4.54... Light receiving section, 8.58... Temperature detection means, 28.84... Temperature correction means.

Claims (1)

[Claims] (1) An optical power meter comprising a light receiving section provided with a photoelectric conversion element that photoelectrically converts an optical signal, and a device main body that measures the value of optical power from the optical signal received by the light receiving section, A temperature detection means for outputting a temperature detection signal corresponding to the temperature change of the photoelectric conversion element is attached to the light receiving section, while a value of the optical power is attached to the main body of the apparatus based on the temperature detection signal detected by the temperature detection means. An optical power meter characterized by being provided with a temperature correction means for correcting.