JPH04223231A - Optical characteristics measuring device and optical parts manufacturing device using it - Google Patents

Abstract

PURPOSE:To enable time response characteristics to be extremely fast and an accurate measurement to be easily performed by modulating a plurality of lights with different frequencies, converting a light which is given to an object into an electrical signal, and obtaining each modulation frequency component. CONSTITUTION:Oscillators 11 and 12 are allowed to oscillate by each specified frequency, a pulse output of the frequency is added to a digital external modulation input terminal of light sources 1 and 2, and the light sources 1 and 2 are modulated. Only a modulated component is taken out of an output from a light detector 6 in a signal processing device 8 and a light power for light with two wavelengths is measured simultaneously. When each modulated component is taken out, a signal from the oscillators 11 and 12 is fed to the signal processing device 8. Light sources 1 and 2 are operated continuously to generate a modulation light and are always maintained to be ON, thus always enabling light to be generated stably, thus eliminate the need for waiting until the light sources 1 and 2 become stable, enabling a measurement at a wavelength of the light sources 1 and 2 to be measured in a short time, and achieving a measurement accordingly even if an object to be measured 4 is fluctuating with time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical property measuring device for measuring optical power at at least two wavelengths, and an optical component manufacturing apparatus constructed using the optical property measuring device.

0002

[Prior Art] Conventionally, in order to know the characteristics of optical components such as optical fiber couplers such as loss and degree of separation at several wavelengths, the optical power at each wavelength has been measured and the power The above characteristics are calculated from the difference or ratio between the two.

[0003] When measuring optical power at two wavelengths, an optical characteristic measuring device is usually constructed as shown in FIG. The light sources 1 and 2 each generate light of different wavelengths, and after the light is combined by an optical coupler 3, the light is made to simultaneously enter the object to be measured 4. The light that has passed through the object to be measured 4 enters a demultiplexer 5 and is separated into wavelengths, and the two separated lights enter photodetectors 6 and 7, respectively.

In this case, in order to optically separate the light output from the object to be measured 4 into wavelengths, a grating, a prism, etc. may be used as the demultiplexer 5, or a wavelength multiplexing method consisting of an optical fiber coupler or the like may be used. A divider (WDM) or a filter is used.

In addition to using light of different wavelengths simultaneously and optically separating each wavelength on the detection side, there are also cases where light of different wavelengths is used in a time-division manner to perform measurements for each wavelength. In this case, as shown in the timing chart of FIG. 2, the light sources 1 and 2 are turned on and off alternately, and when each light source is on, the signal from one photodetector is sampled. If light sources 1 and 2 are turned off for a long time, they will not be stable immediately after being turned on, so it is necessary to capture the signal at timing t after a certain amount of time T (generally about 30 minutes) has elapsed since the light sources 1 and 2 have been turned on. be.

[0006]

[Problem to be Solved by the Invention] However, when light of multiple wavelengths is input at the same time and the output light is optically separated, it is difficult to obtain a large degree of separation. In this case, there is a problem in that when one is larger than the other, it is not possible to measure the smaller one. Furthermore, optical components that separate light into wavelengths are more expensive than electrical components, and are difficult to adjust.Furthermore, they are easily affected by temperature, so there is a problem in that measured values vary greatly depending on temperature.

Furthermore, when using light of multiple wavelengths in a time-sharing manner, it takes a long time for each light source to stabilize, so it takes time to complete all measurements regarding the light of multiple wavelengths, and the When the characteristics change over time, there is a problem in that it is not possible to follow and measure the characteristics.

[0008] Therefore, there is a problem when manufacturing optical components using such an optical measuring device. In other words, when manufacturing a fusion-stretched optical fiber coupler or an optical splitter using a half mirror, it is necessary to input light into the optical component, monitor the emitted light, and adjust the amount of stretching and position. There is. If you use the former optical property measuring device,
In addition to being expensive, it is not easy to manufacture optical components based on accurate measurements due to measurement limits when the light of one wavelength is large and poor temperature characteristics. In addition, the latter type of optical property measuring device has poor temporal response and cannot measure optical power that changes moment by moment, making it impossible to make immediate adjustments according to the optical power, resulting in extremely poor manufacturing efficiency for optical components. Ta.

[0009] In view of the above, an object of the present invention is to provide an inexpensive optical property measuring device that has extremely fast temporal response characteristics and can easily perform accurate measurements.

Another object of the present invention is to provide an optical component manufacturing apparatus that is improved so that optical components can be manufactured easily and efficiently by using an optical property measuring device that has a short measurement time and a wide dynamic range. With the goal.

[0011]

[Means for Solving the Problems] In the optical property measuring device according to the present invention, a plurality of lights having different wavelengths are modulated at different frequencies and applied to an object to be measured, and the light obtained from the object to be measured is converted into an electrical signal. After converting into , the components of each modulation frequency mentioned above are obtained from the electrical signal. Since each of these modulated frequency components relates to light of different wavelengths, measurements of multiple wavelengths can be performed simultaneously, shortening the measurement time for light of multiple wavelengths and greatly improving the temporal response characteristics. It can be done quickly. Further, since the light generating means does not have a period of being off, its output light becomes stable.

Furthermore, in the optical component manufacturing apparatus according to the present invention, the light output from the optical component is simultaneously measured for each wavelength using the optical characteristic measuring device with high temporal response characteristics as described above, and the optical characteristics are measured. The feature is that the optical components are adjusted according to the output of the measuring device, and the ever-changing output light from the optical components can be measured without time delay, making it possible to adjust the optical components immediately and easily. Moreover, it becomes possible to efficiently manufacture optical components.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 3 is a block diagram showing an optical characteristic measuring device according to an embodiment of the present invention. In this diagram, two light sources 1 and 2 with different wavelengths are used to measure the output light power at two wavelengths. . In this case, a laser diode with a wavelength of 1.31 μm was used as the light source 1, and a laser diode with a wavelength of 1.55 μm was used as the light source 2. These lights are combined by an optical coupler 3 such as an optical fiber coupler and made incident on the object to be measured 4. The light emitted from the object to be measured 4 is made incident on one photodetector 6,
The output is sent to the signal processing device 8.

The light sources 1 and 2 are modulated by the outputs of oscillators 11 and 12, respectively. In this embodiment, the oscillators 11 and 12 oscillate at 270 Hz and 1 kHz, respectively, and pulse outputs at these frequencies are applied to the digital external modulation input terminals of the light sources 1 and 2. In the signal processing device 8,
Of the output from the photodetector 6, only the above modulated component is extracted, and the optical powers of the two wavelengths of light are measured simultaneously. Possible methods for extracting each modulation component include an electrical frequency filter method and a synchronous detection method. In the case of the synchronous detection method, signals from each oscillator 11 and 12 are sent to the signal processing device 8 as shown by dotted lines. The light sources 1 and 2 are continuously operated to generate modulated light and are never turned off, so they can always generate light stably. As a result, there is no need to wait for the light sources 1 and 2 to stabilize, and measurements using the two wavelengths of both the light sources 1 and 2 can be completed in a very short time, and the object to be measured 4 changes over time. Even if you are using a computer, you can perform measurements that follow it.

In this embodiment, the signal processing device 8 is specifically constructed as shown in FIG. 4 based on an electrical frequency filter method. In FIG. 4, a signal from the photodetector 6 is input to the signal processing device 8. The photodetector 6 generates a current output corresponding to the incident light, and can be, for example, an InGaAs ternary PIN photodiode with an FC connector and a light receiving diameter of 300 μm.

The current output sent from the photodetector 6 is first converted into a voltage output in the current-voltage converter 81 of the signal processing device 8, and then converted into a voltage output by an amplifier 82, a bandpass filter 83, an amplifier 84, and an effective value. - DC voltage converter 85,
The signal is sent to two signal systems configured by the A/D converter 86. The two bandpass filters 83 and 83 pass only signal components of 270 Hz and 1 kHz, respectively. Since the signals passing through these bandpass filters 83 are sinusoidal waves, an effective value-to-DC voltage converter 85 such as an RMS (root mean square)/DC circuit is used to convert the effective value to a direct current voltage. .

The outputs of these effective value to DC voltage converters 85 are each converted into digital signals by an A/D converter 86 and then sent to a signal processing circuit 87 . The A/D converter 86 can be a built-in personal computer with a resolution of 16 bits, and the signal processing circuit 87 can be a commercially available personal computer. In this signal processing circuit 87, calculations are performed to convert the digital signal into optical power. The resulting optical powers at the two wavelengths are displayed on two displays 88, respectively.

FIG. 5 shows a modification of the signal processing device 8, which is based on a synchronous detection method. A synchronous detection circuit 89 is used in place of the bandpass filter 83, amplifier 84, and effective value-to-DC voltage converter 85 shown in FIG. By sending the pulse outputs of the oscillators 11 and 12 to the two synchronous detection circuits 89 and performing synchronous detection, the wavelength components of the light from the light source 1 and the wavelength components of the light from the light source 2 are respectively extracted. As the synchronous detection circuit 89, a lock-in amplifier or the like can be used.

In the configurations shown in FIGS. 4 and 5,
By increasing the modulation frequency and obtaining light having different modulation frequency components for three or more different wavelength light sources, it is possible to simultaneously measure the optical power characteristics of light of many wavelengths. Measurements can be made simultaneously on multiple wavelengths of light without switching circuits, so
When the optical properties of a material change over time, measurements can be made to follow them.

FIG. 6 shows an apparatus for manufacturing a fused and drawn optical fiber coupler using the optical characteristic measuring apparatus shown in FIGS. 3 to 5. In this figure, two silica-based glass optical fibers 61 and 62 are arranged in parallel in advance, their sides are brought into contact with each other, and clampers 63 and 62 are placed in parallel.
4, and the clamper 63,
34 is extended in the length direction. This clamper 63,
The optical fibers 61 and 62 are heated from the side by a burner 66 between the two. That is, an optical fiber coupler is manufactured by fusing two optical fibers 61 and 62 at their sides. The position of the burner 66 is controlled by a burner position control device 67.

In such an optical fiber coupler manufacturing apparatus, the light branching ratio depends on the amount of stretching. Here, we will manufacture an optical fiber coupler so that the branching ratio at two wavelengths is as desired, and the light source 1 with different wavelengths
. Pulse signals for modulation are applied to the light sources 1 and 2 from oscillators 11 and 12 that oscillate at different frequencies, and these light sources 1 and 2 generate modulated light at different frequencies.

The light emitted from the other ends of the optical fibers 61, 62 is made incident on two photodetectors 6, 6, respectively, and the output thereof is sent to two signal processing devices 8, 8, respectively. At 8 and 8, respective modulated light components are extracted. As a result, optical power measurements for two wavelengths can be obtained simultaneously from the two signal processing devices 8, 8. Note that the optical coupler 3 in FIG. 3 is not used because the object to be measured is an optical fiber coupler and the lights from the two light sources 1 and 2 are coupled.

[0023] Then, the data of the measured value is sent to the control device 6.
8, and the drawing machine 65 and burner position control device 67 are controlled. As mentioned above, the optical characteristic measuring device, which is composed of two oscillators 11 and 12, two light sources 1 and 2, and two systems of light receiving systems including a photodetector 6 and a signal processing device 8, has a fast response and can simultaneously Measurements can be made for two wavelengths. Therefore, the optical fibers 61, 6
Since it is possible to track and measure the power fluctuations at two wavelengths of the light emitted from each of the two wavelengths, it is possible to optimize the position of the burner 66, and when the burner is gradually extended. The branching ratio at the two wavelengths, which changes moment by moment, can be immediately captured and reflected in the amount of stretching. In this way, when the branching ratio for the two wavelengths of light becomes desired, the drawing machine 65 is stopped and the burner 66 is moved back, thereby obtaining an optical fiber coupler with desired wavelength characteristics.

For example, the optical characteristic measuring device according to the present invention can be used when manufacturing an optical splitter using a half mirror. In this case, light from a plurality of light sources of different wavelengths is input into an optical splitter using a half mirror, and the branched lights are each guided to a photodetector via the half mirror. In this way, the emitted light power for a plurality of wavelengths is monitored, and the position of the half mirror is controlled according to the branching ratio at the plurality of wavelengths. Then, the position of the half mirror can be adjusted immediately in response to a change in the branching ratio at a plurality of wavelengths, so that the optical splitter can be manufactured easily and efficiently.

As described above, the optical property measuring device of the present invention is applicable not only to manufacturing equipment for manufacturing fused and drawn optical fiber couplers, but also for manufacturing equipment for manufacturing optical splitters using half mirrors, and other optical properties. Applicable to parts manufacturing equipment.

[0026]

As described above, according to the optical characteristic measuring device of the present invention, it is possible to measure the optical power of light of a plurality of wavelengths with good temporal response characteristics. Therefore, even if the power of the light to be measured fluctuates, it is possible to immediately follow it and obtain measurement data without any time delay.

Furthermore, according to the optical component manufacturing apparatus of the present invention, since an optical property measuring apparatus with good responsiveness that can measure the properties of light of multiple wavelengths is used,
Optical components with desired characteristics can be manufactured easily and efficiently.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional example.

FIG. 2 is a timing chart of another conventional example.

FIG. 3 is a block diagram of an embodiment of an optical property measuring device according to the present invention.

FIG. 4 is a block diagram specifically showing a part of an embodiment of the optical property measuring device.

FIG. 5 is a block diagram specifically showing a part of a modification of the optical property measuring device.

FIG. 6 is a block diagram of an embodiment of an optical component manufacturing apparatus according to the present invention.

[Explanation of symbols]

1, 2 Light source 3 Optical coupler 4
Measured object 5
Duplexer 6, 7
Photodetector 8 Signal processing devices 11, 12 Oscillator 81 Current-voltage converter 8
2, 84 Amplifier 83 Bandpass filter 85 Effective value-DC voltage converter 86 A/D converter 87 Signal processing circuit 88
Displays 61, 62
Optical fiber 63, 34 clamper

Claims (2)

[Claims] 1. A plurality of light generation means for generating light of different wavelengths, a means for modulating the light from the plurality of light generation means at different frequencies, and a plurality of light generation means for generating light from the plurality of light generation means. It is characterized by comprising a means for making the light incident on the object to be measured, a photoelectric conversion means for converting the incident light through the object to an electrical signal, and a means for extracting each of the above-mentioned modulated frequency components from the electrical signal. Optical property measuring device. 2. The optical characteristic measurement according to claim 1, wherein light modulated at different frequencies from a plurality of light generating means with different wavelengths is input to an optical component, and the light output from the optical component is measured. An optical component manufacturing apparatus comprising: a device; and means for adjusting the optical component according to the output of the optical property measuring device.