JPH01303819A - Optical data transmission equipment - Google Patents

Abstract

PURPOSE:To transmit different data with the same wavelength band by using the light having the different spectrum width and light emitting intensity for data. CONSTITUTION:At least two light transmitters 1 and 2 are provided and one side includes a laser element 1 to generate a strong light with a narrow band width as a light emitting element and other side includes a light emitting diode 2 to generate the weak light with a wide band width including the light of the same wavelength band as the laser element. A spectrum component corresponding to the light generated by the laser element 1 is separated, supplied to one light receiver 8 and other component is supplied to other light receiver 9. Thus, for the light generated by the laser element 1, the spectrum width is comparatively narrow, the light intensity of the central wavelength is large, and for the light generated by the light emitting diode 2, the spectrum width is comparatively wide, and therefore, even when these lights mixed, the optical signal from the laser element 1 can be received by separating the central wavelength. At this time, for the optical signal from the light emitting diode 2, the central wavelength component is removed, a remaining spectrum component is large and the low speed sub-data can be sufficiently transmitted.

Description

[Detailed description of the invention] [Industrial application field] The present invention is used for optical communications using optical fibers as transmission paths.

In particular, control information and other relatively low-speed data (hereinafter referred to as "sub-data") are replaced with high-speed data (hereinafter referred to as "main data").
(hereinafter referred to as "optical data transmission device").

〔overview〕

The present invention is an optical data transmission device that transmits at least two sets of data using a common optical fiber transmission line, and by using light with different spectral width and emission intensity for each data, different data can be transmitted in the same wavelength band. It is designed to transmit.

[Conventional example]

In conventional optical data transmission devices, in order to transmit a plurality of data, an optical signal is modulated using electrically multiplexed signals, or wavelength multiplexed using optical signals of different wavelengths.

FIG. 7 is a block diagram of a first conventional optical data transmission device.

The optical transmitter 71 electrically multiplexes the main data a and the sub data b, and modulates the optical signal of wavelength λ1 with the multiplexed electrical signal. This optical signal is sent to the optical fiber transmission line 11 via the optical multiplexer/demultiplexer 73. The optical signal propagated through the optical fiber transmission line 11 is demultiplexed by an optical multiplexer/demultiplexer 74 and supplied to an optical receiver 75 . The optical receiver 75 is
The received optical signal is converted into an electrical signal and further separated into main data a' and sub data b' and output.

The optical transmitter 76 outputs the reverse sub-data C as an optical signal of wavelength λ2, and sends it to the optical fiber transmission line 11 via the optical multiplexer/demultiplexer 74. This optical signal is sent to an optical multiplexer/demultiplexer 73
The signal is demultiplexed by the optical receiver 72, converted into an electrical signal, and output as data C'.

FIG. 8 is a block diagram of a second conventional optical data transmission device.

The optical transmitter 81 modulates the optical signal with the wavelength λ1 using the main data a, and the optical transmitter 82 modulates the optical signal with the wavelength λ2 (
λ2≠λI). These optical signals are
It is sent out to the optical fiber transmission line 11 via the optical multiplexer/demultiplexer 84. The optical signal propagated through the optical fiber transmission line 11 is demultiplexed by an optical multiplexer/demultiplexer 85, an optical signal with a wavelength λi is supplied to an optical receiver 86, and an optical signal with a wavelength λ2 is supplied to an optical receiver 87. . The optical receiver 86 converts the received optical signal into an electrical signal and outputs main data a'. The optical receiver 87 converts the received optical signal into an electrical signal and outputs sub-data b'.

The optical transmitter 88 outputs the reverse sub-data C as an optical signal of wavelength λ3, and sends it to the optical fiber transmission line 11 via the optical multiplexer/demultiplexer 85. This optical signal is sent to an optical multiplexer/demultiplexer 84
The signal is demultiplexed by the optical receiver 83, converted into an electrical signal, and output as data C'.

[Problem that the invention seeks to solve]

However, in the first conventional example, main data and sub-data are electrically multiplexed, which has the disadvantage of increasing the circuit scale and increasing the transmission bit rate. In addition, both the first conventional example and the second conventional example have the disadvantage that, because different wavelengths are used, characteristics of the light emitting element and other elements are strictly required, and manufacturing costs are high.

The present invention solves the above problems, has a small circuit scale, and
It is an object of the present invention to provide an optical data transmission device that can transmit a plurality of data without increasing the transmission bit rate.

[Means for solving problems]

The optical data transmission device of the present invention includes at least two optical transmitters, one of which includes a laser element as a light emitting element that generates strong light with a narrow bandwidth, and the other emits light in the same wavelength band as the laser element. It includes a light emitting diode that generates weak light with a wide bandwidth including It is characterized by comprising a means for supplying.

[For production]

The light generated by the laser element has a relatively narrow spectral width and a high light intensity at the center wavelength. On the other hand, light emitted by light emitting diodes has a relatively wide spectral width. Therefore, even if these lights are mixed, the optical signal from the laser element can be received by separating the center wavelengths.

At this time, the center wavelength component of the optical signal from the light emitting diode is removed, but the remaining spectral component is large and low-speed sub-data can be sufficiently transmitted.

〔Example〕

FIG. 1 is a block diagram of an optical data transmission apparatus according to an embodiment of the present invention.

This device includes an optical fiber transmission line 11, two optical transmitters 1.2 that send optical signals to the optical fiber transmission line 11 via an optical multiplexer/demultiplexer 5, and an optical signal transmitted from the optical fiber transmission line 11. One of the two optical transmitters 1.2, that is, the optical transmitter 1, is a laser element that generates strong light with a narrow bandwidth as a light emitting element, For example, it includes a laser diode, and the other side, that is, the optical transmitter 2, includes a light emitting diode that generates weak light with a wide bandwidth that includes light in the same wavelength band as the laser diode, and the light emitted by the laser diode An optical multiplexer/demultiplexer 6 is provided which separates spectral components corresponding to and supplies them to an optical receiver 8 and supplies other components to an optical receiver 9.

Further, in this embodiment, in order to transmit sub-data in the reverse direction, an optical receiver 3 including a light emitting diode and an optical multiplexer/demultiplexer 4 are used.
, an optical multiplexer/demultiplexer 7 and an optical transmitter IO.

The optical transmitter 1 modulates the output light of the laser diode according to the main data a, and outputs it to the optical fiber transmission line 11 via the optical multiplexer/demultiplexer 5. The optical transmitter 2 modulates the output light of the light emitting diode with the sub data b, and sends this optical signal to the optical fiber transmission line 11 via the optical multiplexer/demultiplexers 4 and 5.

The optical multiplexer/demultiplexer 6 separates the optical signal from the optical data transmission line 11 and supplies the optical signal from the optical transmitter 1 to the optical receiver 8.
The optical signal from the optical transmitter 2 is supplied to the optical receiver 9 via the optical multiplexer/demultiplexer 7. The optical receiver 8.9 converts the received optical signal into an electrical signal, and outputs main data a' and sub-data b', respectively.
Output.

The optical transmitter 10 modulates the output light of the light emitting diode using the sub data C and sends it to the optical fiber transmission line 11 via the optical multiplexer/demultiplexer 7.6. This optical signal is sent to the optical multiplexer/demultiplexer 5.
4 to the optical receiver 3. The optical receiver 3 converts this optical signal into an electrical signal and outputs sub-data C'.

Figure 2 shows the emission spectrum of a laser diode,
FIG. 3 shows the emission spectrum of a light emitting diode.

The center wavelength of the two elements is λ0, the output of the laser diode has a narrow spectral bandwidth, and the output of the light emitting diode has a wide spectral bandwidth.

FIG. 4 shows the relative intensities of the laser diode output light and the light emitting diode output light.

Although the laser diode output vector 12 has a narrow spectrum, it has a much higher relative intensity than a light emitting diode. The output vector 13 of a light emitting diode has a large bandwidth spread, but its relative intensity is very small compared to a laser diode.

FIG. 4 also shows the characteristics of the optical multiplexer/demultiplexer 5.6. A broken line 14 indicates the wavelength loss characteristic from the optical transmitter 1 to the optical fiber transmission line 11 in the optical multiplexer/demultiplexer 5 and from the optical fiber transmission line 11 to the optical receiver 8 in the optical multiplexer/demultiplexer 6. Furthermore, the - dashed line 15 represents the wavelength loss characteristics from the optical multiplexer/demultiplexer 4 in the optical multiplexer/demultiplexer 5 to the optical fiber transmission line 11 and from the optical fiber transmission line 11 in the optical multiplexer/demultiplexer 6 to the optical multiplexer/demultiplexer 7. show.

FIG. 5 shows the input optical spectrum 12' of the optical receiver 8,
FIG. 6 shows the artificial light spectrum 13' of the optical receiver 3.9. The input light of the optical receiver 8 includes light components of light emitting diodes for transmitting sub-data, but since the difference in intensity is large, the influence on the transmission characteristics is small. Furthermore, the human power light of the optical receiver 3.9 has a spectrum with a missing center spectrum, but since the spread is large, the residual spectral component is also large, and the effect of the missing spectrum on the transmission characteristics is small.

Optical multiplexer/demultiplexer that multiplexes and demultiplexes light from light emitting diodes 4.7
As such, a simple half-mirror type optical component can be used.

〔Effect of the invention〕

As explained above, since the optical data transmission device of the present invention does not perform multiplexing using electrical signals, the circuit scale can be reduced. It also does not increase the transmission bit rate. Furthermore, although the same frequency band is used, the frequency separation does not need to be strict and can be implemented using simple optical components.

Generally, the transmission bit rate of sub-data including control signals and the like is much lower than that of main data. The present invention is particularly effective when used to transmit two pieces of data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical data transmission apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the emission spectrum of a laser diode. FIG. 3 is a diagram showing the emission spectrum of a light emitting diode. FIG. 4 is a diagram showing the relative intensity of the output light of the laser diode and the output light of the light emitting diode and the characteristics of the optical multiplexer/demultiplexer. FIG. 5 is a diagram showing the input optical spectrum of the optical receiver 8. FIG. 6 is a diagram showing the human power optical spectrum of the optical receiver 3.9. FIG. 7 is a block diagram of a plotter of a first conventional optical data transmission device. FIG. 8 is a block diagram of a plotter of a second conventional optical data transmission device. ■, 2.10.71.76.81.82.88... Optical transmitter, 3.8.9.72.75.83.86.87.
...Optical receiver, 4.5.6.7.73.74.84.8
5... Optical multiplexer/demultiplexer, 11... Optical fiber transmission line. Patent applicant: NEC Corporation 1. ．． 1. I''; Agent Patent Attorney Nao Ide Yupa.

Claims (1)

[Claims] 1. An optical fiber transmission line, at least two optical transmitters that send optical signals to this optical fiber transmission line, and at least two optical receivers that receive optical signals from this optical fiber transmission line. In the optical data transmission device, one of the two optical transmitters includes a laser element that generates strong light with a narrow bandwidth as a light emitting element, and the other one contains light in the same wavelength band as this laser element. includes a light emitting diode that generates weak light with a wide bandwidth, the laser device separates a spectral component corresponding to the light generated by the laser element and supplies it to one of the two optical receivers, and supplies the other component to one of the two optical receivers. 1. An optical data transmission device comprising means for supplying data to the other of the two optical receivers.