KR100634124B1 - Digtal optical delay apparatus - Google Patents

Abstract

A digital optical delay apparatus is provided to enable D/Ds to be connected to O/Es and delay an electrical signal inputted from the O/Es as much as predetermined time, and output the electrical signal, thereby minimizing an insertion loss, providing a small-sized and low-priced digital optical delay apparatus because of not using lots of optical fiber, and maintaining the connection of communication even when power is off. O/Es(Optical to Electrical converter)(111,112) are connected to optical cables(101,102) and converts an optical signal transmitted to the optical cables(101,102) into an electrical signal. D/Ds(Digital Delay)(121,122) are connected to the O/Es(111,112) and delays the electrical signal inputted from the O/Es(111,112) as much as predetermined time, and outputs the electrical signal. E/Os(Electrical to Optical converter)(131,132) are connected to the D/Ds and converts the electrical signal inputted from the D/Ds into the optical signal, and transmits the optical signal to the optical cable(101,102).

Description

Digital Optical Delay Apparatus {Digtal Optical Delay Apparatus}

1 is a view schematically showing an optical delay apparatus according to the prior art,

2 is a view schematically showing a first embodiment of a digital optical delay apparatus according to the present invention;

3 is a view schematically showing a second embodiment of a digital optical delay apparatus according to the present invention;

4 is a view schematically showing a third embodiment of a digital optical delay apparatus according to the present invention;

5 is a diagram schematically showing a fourth embodiment of a digital optical delay apparatus according to the present invention.

* Explanation of symbols for main parts of drawings *

100,200,300,400; Digital optical delay device

101,102; Light path 103; Auxiliary line

104,105; Delay lines 111,112,113,114; Photoelectric converter

121,122,123,124; Digital delays 131,132,133,134; Electro-optical converter

140,140 ', 150,150'; Mux / demux 161,162; Optical switch

141,142,143,144,151,152,153,154; Photo Insert Extractor

The present invention relates to an optical delay apparatus, and more particularly, to a digital optical delay apparatus capable of obtaining a necessary optical delay time using a digital delay.

Mobile communication enables communication between mobile stations by transmitting signals of mobile stations such as mobile phones by a plurality of base stations that can cover an area of a predetermined area. However, in an area covered by one base station, there may be a shade area that is difficult to reach a radio wave such as a radio wave blocking area or a tunnel or an underground parking lot due to a mountain, a building, or other features. A repeater is used to amplify the signal so that the signal of the base station can reach the area, and service the shadow area, and connect the signal of the shadow area terminal to the base station. Such a repeater can transmit high quality signals by transmitting the RF signal between the repeater and the base station to the service area by using optical communication with excellent characteristics, and can realize a high power service in a wider area, and can also be used as a substitute for a simple base station. Optical repeaters are widely used.

However, when the mobile communication user moves between the optical repeater and the optical repeater, a signal may be disconnected between the mobile stations. In order to prevent this, an optical delay device is used for an optical repeater or a base station to delay the optical signal transmitted for a predetermined time.

Figure 1 shows a brief optical delay apparatus according to the prior art.

Referring to FIG. 1, in the optical delay apparatus according to the related art, the input unit 10, the optical switches 21 to 27, the optical path selection lines 41 to 46, and the optical path non-selection lines 31 to 27, to which an optical signal for delay is input, are input. Optical path selectors 31 to 36 and 41 to 46 composed of 36, optical paths 51 to 56 composed of optical fibers of a predetermined length, and delay time display sections 61 to 66 of the selected optical path. Hereinafter, each of the optical path selection sections 31 to 36 and 41 to 46 and the optical paths 51 to 56 are classified into one section and described. That is, the first section is composed of the optical path 51 and the optical path selector 31 and 41, and the second section is composed of the optical path 52 and the optical path selector 32 and 42. Will be. The light paths of the light path selecting sections 31 to 36 and 41 to 46 are selected by the on / off operation of the optical switches 21 to 27. That is, when each optical switch 21 to 27 is turned on, the optical path selection lines 41 to 46 are selected to transmit an optical signal to the corresponding optical paths 51 to 56. Thus, the six sections are controlled on and off by respective optical switches 21 to 26. Hereinafter, for convenience of explanation, the plurality of optical switches 21 to 26 will be described as the first optical switch 21 to the sixth optical switch 26, respectively.

The optical switches 21 to 27 are controlled to select the flow of the optical signal of each section by an external control signal (not shown). Specifically, when the optical paths 51 to 56 having a predetermined delay time are to be selected by the control signal, the optical signals inputted to the input unit 10 flow to the optical path selection lines 41 to 46. 21 to 27). When the predetermined optical paths 51 to 56 are to be omitted, the optical paths 31 to 36 are made to flow. Further, when each of the optical paths 51 to 56 is selected, a delay occurs by the time displayed on the delay time display sections 61 to 66 of each optical path. The optical fiber delay time is in units of milliseconds. That is, the optical delay device is a device for delaying light from 1 kHz to 40 kHz.

When all the light paths 51 to 56 are selected by input light passing through the light path selection lines 41 to 46 by respective optical switches 21 to 27, 40 ㎲ (1 + 2 + 4 + 8 + 16) is selected. If the optical delay of + 9 = 40 is generated and none is selected, the optical delay of 0 kHz is generated when the unselected lines 31 to 36 are selected. On the other hand, in order to achieve an optical delay of 8 ㎲, the first optical switch 21 to the third optical switch 23 and the fifth optical switch 25 to the sixth optical switch 26 are turned off through control signals. By selecting the unselected lines 31 to 33, 35, 36, the light does not pass through the optical path, and the fourth optical switch 24 is turned on so that the optical path selection line 44 is selected. Therefore, the incident light passes through the optical path 54 alone, resulting in a total of 8 kHz optical delays.

The optical delay device using the optical fiber as described above is practically used because optical delay of a specific range (1 ㎲ to 40 ㎲) can be obtained by using the arrangement of the optical switch and the length difference of each optical fiber.

As described above, the optical delay apparatus using the optical fiber is convenient because the desired delay time can be generated by combining the necessary optical delay time, but there is a problem that the delay time must be solved by the length of the optical fiber. That is, in order to generate the optical delay time of 40 kHz normally required between the repeaters, an optical fiber of 8 km is required. However, an expensive cost is required to construct an 8 Km optical fiber, and there is a problem that the volume of the optical delay device is increased because a long optical fiber is used.

In addition, since the required delay time is generated using the length of the optical fiber, the longer the delay time, the larger the insertion loss.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a digital optical delay apparatus capable of minimizing insertion loss and reducing size and cost as compared with the related art.

An object of the present invention as described above, the photoelectric converter is connected to the optical path, and converts the optical signal transmitted to the optical path into an electrical signal; A digital delay connected to the photoelectric converter and outputting a predetermined time delay of the electrical signal input from the photoelectric converter; It is achieved by providing a digital optical delay device, comprising; an electro-optical converter connected to the digital delay, and converts the electrical signal output from the digital delay into an optical signal to be transmitted to the optical path.

In another aspect of the present invention, an object of the present invention as described above comprises: a first mux / demux connected to an optical path and having a plurality of channels; At least one first photoelectric converter connected to at least one channel to which an optical signal is output among a plurality of channels of the first mux / demux and converting the output optical signal into an electrical signal; A first digital delay connected to the first photoelectric converter and outputting an electrical signal inputted from the first photoelectric converter by a predetermined time delay; A first electro-optical converter connected to the first digital delay and converting an electrical signal output from the first digital delay into an optical signal; A second mux / demux connected to an optical path and one of the plurality of channels connected to the first electro-optic converter; At least one second photoelectric converter connected to at least one channel for outputting an optical signal among the plurality of channels of the second mux / demux and converting the output optical signal into an electrical signal; A second digital delay connected to the second photoelectric converter and outputting an electrical signal input from the second photoelectric converter by a predetermined time delay; And a first electro-optical converter connected to the second digital delay and converting an electrical signal output from the second digital delay into an optical signal and transmitting the optical signal to the first mux / demux. Is achieved.

Here, the first and second mux / demux of the digital optical delay apparatus according to an embodiment have two channels. In this case, it is preferable that the two channels transmit optical signals having wavelengths of 1,310 nm and 1,550 nm, respectively.

In still another aspect of the present invention, an object of the present invention as described above is provided between a first optical line, an auxiliary optical line, and a first delay line, and selectively connects the first optical line with one of the auxiliary optical line and the first delay line. A first optical switch for connecting; A first mux / demux connected to the first delay line and having a plurality of channels; At least one first photoelectric converter connected to at least one channel to which an optical signal is output among a plurality of channels of the first mux / demux and converting the output optical signal into an electrical signal; A first digital delay connected to the first photoelectric converter and outputting an electrical signal inputted from the first photoelectric converter by a predetermined time delay; A first electro-optical converter connected to the first digital delay and converting an electrical signal output from the first digital delay into an optical signal; A second mux / demux connected to an optical path and one of the plurality of channels connected to the first electro-optic converter; At least one second photoelectric converter connected to at least one channel for outputting an optical signal among the plurality of channels of the second mux / demux and converting the output optical signal into an electrical signal; A second digital delay connected to the second photoelectric converter and outputting an electrical signal input from the second photoelectric converter by a predetermined time delay; A first electro-optical converter connected to the second digital delay and converting an electrical signal output from the second digital delay into an optical signal and transmitting the optical signal to the first mux / demux; And a second optical switch installed between a second optical line, the auxiliary optical line, and a second delay line, and selectively connecting a second optical line with one of the auxiliary optical line and the second delay line. Is achieved by providing

Here, the first and second mux / demux of the digital optical delay apparatus according to an embodiment have two channels. In this case, it is preferable that the two channels transmit optical signals having wavelengths of 1,310 nm and 1,550 nm, respectively.

Also, the digital optical delay apparatus according to another embodiment has first and second mux / demux having four channels.

The first and second optical switches may be configured such that when the power is turned off, the first optical path and the second optical path are connected to the auxiliary optical path.

Hereinafter, embodiments of the digital optical delay apparatus according to the present invention will be described with reference to the accompanying drawings.

Referring to FIG. 2, the digital optical delay apparatus 100 according to the first embodiment of the present invention includes a photoelectric converter 111, a digital delay 121, and an electro-optical converter 131.

An optical to electrical converter (O / E) 111 is connected to the first optical path 101, and converts an optical signal transmitted to the first optical path 101 into an electrical signal to convert a digital delay 113 into an electrical signal. Will output As the photoelectric converter 111, a laser diode capable of converting an electrical signal into an optical signal is used. At this time, the laser diode should select a laser diode of the appropriate specification according to the optical signal transmitted.

The digital delay (D / D) 121 is connected between the photoelectric converter 111 and the electro-optical converter 131, and outputs an electric signal input from the photoelectric converter 111 by a predetermined time delay. The digital delay 121 is a device for delaying and outputting an input electric signal by a set time, and thus the detailed description thereof will be omitted. Although the delay time of the electric signal of the digital delay 121 may be fixed, it may be set by a control signal by a time setting unit (not shown) separately installed.

An electrical to optical converter (E / O) 131 is connected to the digital delay 121 and converts the electrical signal output from the digital delay 121 into an optical signal to the second optical path 102. send. As the electro-optical converter 131, a photo diode capable of converting an optical signal into an electric signal is frequently used.

Therefore, the operation of the digital optical delay apparatus 100 according to the first embodiment of the present invention as described above is as follows.

When an optical signal is input to the first optical path 101, the photoelectric converter 111 converts the optical signal into an electrical signal and outputs the electrical signal to the digital delay 121. The electrical signal input to the digital delay 121 is delayed by the time set in the digital delay 121 and input to the electro-optical converter 131. Then, the electro-optical converter 131 converts the input electric signal into an optical signal and transmits it to the second optical path 102. Therefore, the optical signal output to the second optical path 102 is delayed by the time set in the digital delay 121 compared to the optical signal input to the first optical path 101.

3 is a diagram schematically illustrating a digital optical delay apparatus 200 according to a second embodiment of the present invention.

Referring to FIG. 3, the digital optical delay apparatus 200 according to the second embodiment of the present invention includes first and second mux / demuxes 140 and 150, a plurality of photoelectric converters 111 and 112, and a plurality of electro-optical converters. 131, 132, and digital delays 121, 122.

The first and second mux / demux (140,150) is a device that separates the optical signal incident to a single optical path into a plurality of optical signals, or combines so that several optical signals can be sent to a single optical beam, once in the optical path It is connected and the other end has a plurality of channels corresponding to the number of optical signals to be separated. The first and second mux / demux 140,150 may be any mux / demux of any type as long as it can send a plurality of optical signals in one optical path, but in the present embodiment, a low density wavelength division multiplexing method ( CWDM) mux / demux is used, and two optical signals are transmitted in one optical path.

The first and second mux / demux 140 and 150 of the digital optical delay apparatus 200 according to the present embodiment are connected to the first and second optical paths 101 and 102, respectively, and have two channels. Thus, each mux / demux 140, 150 is composed of two light insertion extractors 141, 142 and 151, 152 forming each channel. The first and third light insertion extractors 141 and 151 transmit an optical signal having a wavelength of 1,350 nm and reflect the remaining optical signals. The second and fourth light insertion extractors 142 and 152 transmit an optical signal having a wavelength of 1,550 nm and reflect the remaining optical signals.

The photoelectric converters 111 and 112 convert an optical signal into an electrical signal, and the quantity of use is determined according to the number of channels of the first and second mux / demux 140 and 150. In the present embodiment, two photoelectric converters 111 and 112 are used. The first photoelectric converter 111 is installed between the first photoinsert extractor 141 and the first digital delay 121 of the first mux / demux 140, and the second photoelectric converter 112 is the second mux. / Is installed between the fourth optical insertion extractor 152 and the second digital delay 122 of the demux 150.

The plurality of digital delays 121 and 122 receive an electrical signal from the photoelectric converters 111 and 112 and delay the electric signal for a predetermined time and output the same. The quantity of use is determined according to the number of channels of the first and second mux / demux 140 and 150. All. The first digital delay 121 is installed between the first photoelectric converter 111 and the first electro-optical converter 131, and the second digital delay 122 is the second photoelectric converter 112 and the second electro-optical converter. 132 is installed between.

The plurality of electro-optical converters 131 and 132 convert an electric signal into an optical signal, and the quantity of use is determined according to the number of channels of the first and second mux / demux 140 and 150. In the present embodiment, two electro-optical converters 131 and 132 are used. The first electro-optic converter 131 is installed between the third light insertion extractor 151 of the second mux / demux 150 and the first digital delay 121, and the second electro-optic converter 132 is formed of a first electro-optic converter 132. It is installed between the second optical insertion extractor 142 and the second digital delay 122 of the one mux / demux 140.

In the above description, since the plurality of photoelectric converters 111 and 112, the electro-optical converters 131 and 132, and the digital delays 121 and 122 are the same as in the above-described first embodiment, detailed descriptions thereof are omitted.

Hereinafter, the operation of the digital optical delay apparatus 200 according to the second embodiment of the present invention as described above will be described with reference to FIG. 3.

First, a case in which an optical signal including a wavelength of 1,310 nm is input to the first optical path 101 will be described. The optical signal input to the first optical path 101 is introduced into the first optical insert extractor 141 of the first mux / demux 140. The first optical insert extractor 141 transmits an optical signal having a wavelength of 1,310 nm among the input optical signals, and reflects an optical signal having a different wavelength. The optical signal transmitted through the first optical insertion extractor 141 is converted into an electrical signal by the first photoelectric converter 111 and input to the first digital delay 121. The electrical signal input to the first digital delay 121 is delayed for a predetermined time and then output to the first electro-optical converter 131. The electrical signal input to the first electro-optic converter 131 is converted into an optical signal having a wavelength of 1,310 nm and input to the third light insertion extractor 151 of the second mux / demux 150. Therefore, the optical signal output from the first electro-optic converter 131 passes through the third light insertion extractor 151 of the second mux / demux 150 and is transmitted to the second optical path 102.

Next, the case where the optical signal including the 1,550nm wavelength is input to the second optical path 102 will be described. The optical signal input to the second optical path 102 is introduced into the third optical insert extractor 151 of the second mux / demux 150. Since the third light insert extractor 151 transmits an optical signal having a wavelength of 1,310 nm among the input optical signals and reflects an optical signal having a different wavelength, the optical signal having a wavelength of 1,550 nm is reflected to reflect the fourth light insert extractor 152. Is entered. Since the fourth light insert extractor transmits an optical signal having a wavelength of 1,550 nm and reflects an optical signal having a different wavelength, the optical signal having a wavelength of 1,550 nm passes through the fourth light insert extractor 152. The optical signal transmitted through the fourth optical insertion extractor 152 is converted into an electrical signal by the second photoelectric converter 112 and input to the second digital delay 122. The electrical signal input to the second digital delay 122 is delayed for a predetermined time and then output to the second electro-optical converter 132. The electrical signal input to the second electro-optic converter 132 is converted into an optical signal having a wavelength of 1,550 nm and input to the second light insertion extractor 142 of the first mux / demux 140. Therefore, the optical signal output from the second electro-optic converter 132 passes through the second light insertion extractor 142 of the first mux / demux 140 and is transmitted to the first optical path 101.

That is, the optical signal introduced into the first optical path 101 is delayed by the time set in the first digital delay 121 to be transmitted to the second optical path 102 and the optical signal introduced into the second optical path 102. The signal is delayed by the time set in the second digital delay 122 and transmitted to the first optical path 101.

In the above, when only one type of wavelength of the optical signal input to the first optical path 101 and the second optical path 102 is delayed and transmitted to the second optical path 102 and the first optical path 101. Although only the above description has been made, it is obvious that a plurality of wavelengths of optical signals input to the first and second optical paths 101 and 102 may be delayed and transmitted to the second and first optical paths 102 and 101. That is, only one type of wavelength of the optical signal input to the first optical path 101 is delayed and transmitted to the second optical path 102, and two types of optical signals input to the second optical path 102 are used. The wavelength may be delayed to be transmitted to the first optical path 101.

4 is a diagram schematically showing a third embodiment of a digital optical delay apparatus according to the present invention.

Referring to FIG. 4, the digital optical delay apparatus 300 according to the third embodiment includes first and second optical switches 161 and 162, first and second mux / demuxes 140 and 150, and a plurality of photoelectric converters 111 and 112. ), A plurality of electro-optical converters 131 and 132, digital delays 121 and 122, and an auxiliary optical line 103.

The first and second optical switches 161 and 162 select an optical signal flowing into the optical paths 101 and 102 to flow to one of the auxiliary optical paths 103 and the delay lines 104 and 105 provided with the digital delays 121 and 122. The first optical switch 161 is installed between the first optical path 101 and the auxiliary light 103 and between the first delay line 104, and connects the first optical path 101 with the auxiliary optical path 103. Optionally connect with one of the first delay line (104). The second optical switch 162 is installed between the second optical path 102, the auxiliary optical path 103, and the second delay line 105, and the second optical path 102 is connected to the auxiliary optical path 103. Optionally connect with one of the second delay line (105). The optical switches 161 and 162 may preferably use non-latch type optical switches that return to their original positions when the power is turned off. At this time, when the power is turned off and the optical switches 161 and 162 are in the original position, the first and second optical paths 101 and 102 and the auxiliary optical path 103 are connected to each other.

The first and second mux / demux 140 and 150 are connected to the first and second delay lines 104 and 105, respectively, and have two channels. Since the configurations of the first and second mux / demux 140 and 150 are the same as in the above-described second embodiment, a detailed description thereof will be omitted.

In addition, since the photoelectric converters 111 and 112, the electro-optical converters 131 and 132, and the digital delays 121 and 122 are the same as those of the second embodiment, detailed descriptions thereof are omitted.

Hereinafter, an operation of the digital optical delay apparatus 300 according to the third embodiment of the present invention will be described with reference to FIG. 4.

When the power is supplied, the first optical path 101 and the first delay line 104 are connected by the first optical switch 161, and the second optical path 162 is connected by the second optical switch 162. 102 and the second delay line 105 is connected.

In this state, when an optical signal enters the first optical path 101, the optical signal passes through the first optical switch 161 and enters the first delay line 104. The optical signal introduced into the first delay line 104 is introduced into the first optical insert extractor 141 of the first mux / demux 140. Only the optical signal having a wavelength of 1,310 nm among the optical signals introduced into the first optical insert extractor 141 is delayed by the set value of the first digital delay 121 and transmitted to the second optical path 102. Since it is the same as the example, detailed description is omitted.

When an optical signal is input to the second optical line 102, the optical signal passes through the second optical switch 162 and enters the second delay line 105. The optical signal introduced into the second delay line 105 is introduced into the third optical insert extractor 151 of the second mux / demux 150. Only the optical signal having a wavelength of 1,550 nm among the optical signals introduced into the third optical insertion extractor 151 is delayed by the set value of the second digital delay 122 and transmitted to the first optical path 101. Since it is the same as the example, detailed description is omitted.

If the power is turned off during use, the first and second optical switches 161 and 162 are in the non-latch type and are in the home position. At this time, since the auxiliary optical path 103 is connected to the original positions of the first and second optical switches 161 and 162, the optical signal introduced into the first optical path 101 is transferred to the second optical path through the auxiliary optical path 103. Is output to 102. On the contrary, the optical signal introduced into the second optical path 102 is output to the first optical path 101 through the auxiliary optical path 103. Therefore, when the digital optical delay apparatus 300 according to the present embodiment is used, even when the power applied to the digital optical delay apparatus 300 is turned off, the first optical path 101 and the second optical path 102 are closed. The optical signal is transmitted through it so that communication can continue. However, since the optical signal is not delayed as necessary, communication quality is lowered.

5 is a diagram schematically showing a fourth embodiment of a digital optical delay apparatus according to the present invention.

Referring to FIG. 5, the digital optical delay apparatus 400 according to the fourth embodiment of the present invention includes first and second optical switches 161 and 162 and first and second mux / demuxes 140 'and 150'. And a plurality of photoelectric converters 111 to 114, a plurality of electro-optical converters 131 to 134, a plurality of digital delays 121 to 124, and an auxiliary optical path 103. Similar to the digital optical delay device 300 by.

However, the first and second mux / demux 140 '. 150' have four channels, and thus the photoelectric converters 111 to 114, the electro-optical converters 131 to 134, and the digital delays 121 to Only the points in which 124) are included four are different. Accordingly, the digital optical delay apparatus 400 according to the fifth embodiment can transmit two kinds of wavelengths from the first optical path 101 to the second optical path 102, and the second optical path 102 Two kinds of wavelengths can be transmitted to the first transmission path 101.

In addition, since the operation of the digital optical delay apparatus 400 according to the fourth embodiment is similar to that of the digital optical delay apparatus 300 according to the third embodiment, detailed description thereof will be omitted.

Although not described and illustrated herein, it is obvious that the concept of the digital optical delay apparatus 100, 200, 300, or 400 according to the present invention may be applied to six or more channels according to the number of channels of mux / demux.

In addition, in the present specification, only the case in which the types of wavelengths that can be transmitted from the first optical path 101 to the second optical path 102 or the reverse direction thereof are symmetrical with each other, such as 1: 1 and 2: 2, has been illustrated and described. In this case, the type of wavelengths that can be transmitted from the first optical path 101 to the second optical path 102 or the reverse direction thereof may be applied to an asymmetric type such as 1: 2, 1: 3, 2: 1, and 3: 1. Of course it is.

As described above, the digital optical delay apparatus according to the present invention delays the optical signal by the digital delay, thereby minimizing the insertion loss compared to the conventional optical delay apparatus which delays the optical signal using the optical fiber dummy.

In addition, since the optical fiber stack is not used, a small size and a low cost digital optical delay device can be provided.

In addition, the digital optical delay apparatus according to the present invention can maintain communication connection even when the power is turned off.

The present invention is not limited to the specific embodiments described above, but can be performed by a person skilled in the art to which the present invention pertains without departing from the spirit of the present invention described in the claims below. Substitutions, additions, deletions, and alterations fall within the scope of the claims.

Claims (9)

A photoelectric converter connected to an optical path and converting an optical signal transmitted to the optical path into an electrical signal; A digital delay connected to the photoelectric converter and outputting a predetermined time delay of the electrical signal input from the photoelectric converter; And an electro-optical converter connected to the digital delay and converting an electrical signal output from the digital delay into an optical signal and transmitting the optical signal to a light beam. A first mux / demux connected to the optical path and having a plurality of channels; At least one first photoelectric converter connected to at least one channel to which an optical signal is output among a plurality of channels of the first mux / demux and converting the output optical signal into an electrical signal; A first digital delay connected to the first photoelectric converter and outputting an electrical signal input from the first photoelectric converter by a predetermined time delay; A first electro-optical converter connected to the first digital delay and converting an electrical signal output from the first digital delay into an optical signal; A second mux / demux connected to an optical path and one of the plurality of channels connected to the first electro-optic converter; At least one second photoelectric converter connected to at least one channel for outputting an optical signal among the plurality of channels of the second mux / demux and converting the output optical signal into an electrical signal; A second digital delay connected to the second photoelectric converter and outputting an electrical signal input from the second photoelectric converter by a predetermined time delay; And a first electro-optic converter connected to the second digital delay and converting an electrical signal output from the second digital delay into an optical signal and transmitting the optical signal to the first mux / demux. Delay device. The method of claim 2, wherein the first and second mux / demux, A digital optical delay device having two channels. 4. The digital optical delay apparatus according to claim 3, wherein the two channels transmit optical signals having wavelengths of 1,310 nm and 1,550 nm, respectively. A first optical switch installed between the first optical line, the auxiliary optical line, and the first delay line, and selectively connecting the first optical line with one of the auxiliary optical line and the first delay line; A first mux / demux connected to the first delay line and having a plurality of channels; At least one first photoelectric converter connected to at least one channel of the plurality of channels of the first mux / demux to output an optical signal, and converting the output optical signal into an electrical signal; A first digital delay connected to the first photoelectric converter and outputting an electrical signal input from the first photoelectric converter by a predetermined time delay; A first electro-optical converter connected to the first digital delay and converting an electrical signal output from the first digital delay into an optical signal; A second mux / demux connected to an optical path and one of the plurality of channels connected to the first electro-optic converter; At least one second photoelectric converter connected to at least one channel for outputting an optical signal among the plurality of channels of the second mux / demux and converting the output optical signal into an electrical signal; A second digital delay connected to the second photoelectric converter and outputting an electrical signal input from the second photoelectric converter by a predetermined time delay; A first electro-optical converter connected to the second digital delay and converting an electrical signal output from the second digital delay into an optical signal and transmitting the optical signal to the first mux / demux; And And a second optical switch installed between a second optical line, the auxiliary optical line, and a second delay line, and selectively connecting the second optical line with one of the auxiliary optical line and the second delay line. Optical delay device. The method of claim 5, wherein the first and second mux / demux, A digital optical delay device having two channels. 7. The digital optical delay apparatus according to claim 6, wherein the two channels transmit optical signals having wavelengths of 1,310 nm and 1,550 nm, respectively. The method of claim 5, wherein the first and second mux / demux, Digital optical delay device characterized in that it has four channels. 9. The digital display device according to any one of claims 5 to 8, wherein the first and second optical switches are configured such that the first optical path and the second optical path are connected to the auxiliary optical path when the power is turned off. Optical delay device.

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