WO2024042630A1 - Dispositif de transmission optique et procédé de génération de signal optique - Google Patents

Dispositif de transmission optique et procédé de génération de signal optique Download PDF

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Publication number
WO2024042630A1
WO2024042630A1 PCT/JP2022/031807 JP2022031807W WO2024042630A1 WO 2024042630 A1 WO2024042630 A1 WO 2024042630A1 JP 2022031807 W JP2022031807 W JP 2022031807W WO 2024042630 A1 WO2024042630 A1 WO 2024042630A1
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WO
WIPO (PCT)
Prior art keywords
optical
signal
optical comb
light
comb
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PCT/JP2022/031807
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English (en)
Japanese (ja)
Inventor
利明 下羽
陽一 深田
暁弘 田邉
遼 宮武
真良 関口
Original Assignee
日本電信電話株式会社
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Application filed by 日本電信電話株式会社 filed Critical 日本電信電話株式会社
Priority to PCT/JP2022/031807 priority Critical patent/WO2024042630A1/fr
Publication of WO2024042630A1 publication Critical patent/WO2024042630A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation

Definitions

  • the present invention relates to an optical transmitter and an optical signal generation method.
  • FIG. 2 is a diagram schematically showing an optical video distribution system.
  • the optical video distribution system shown in FIG. 2 includes an optical transmitter and an optical receiver. The optical transmitter and the optical receiver are connected by an optical network.
  • the optical transmitter includes an FM batch conversion section and an electrical/optical conversion section.
  • the FM batch conversion unit batch converts input signals such as frequency-multiplexed video signals into wideband FM signals centered around 3 GHz.
  • the electrical/optical converter converts the broadband FM signal into a light intensity modulation signal and outputs the signal.
  • the output optical intensity modulated signal is transmitted through the optical network.
  • Optical networks enable wide-area optical transmission by connecting optical amplifiers such as EDFAs (erbium-doped fiber amplifiers) and optical distributors in multiple stages.
  • the optical receiver receives the optical intensity modulated signal transmitted through the optical network.
  • the optical receiving device includes an optical/electrical conversion section, a delay detection section, and an amplification section.
  • the optical/electrical converter converts the received optical intensity modulation signal into a wideband FM signal.
  • the delay detection section demodulates the wideband FM signal into the original signal.
  • the amplification section amplifies the demodulated signal to a level suitable for the system, and then outputs the amplified signal.
  • FIG. 3 is a diagram illustrating an example of functional blocks of an optical transmitter in the FM batch conversion method (see, for example, Non-Patent Document 3).
  • the optical transmitter shown in FIG. 3 includes a first light source, an optical phase modulation section, a multiplexing section, a second light source, a light receiving section, a light intensity modulation section, and a third light source.
  • the output light from the first light source is input to the subsequent optical phase modulation section.
  • the optical phase modulation section phase modulates the output light from the first light source using the first input signal and the second input signal.
  • the first input signal is a frequency multiplexed signal from 90 to 770 MHz
  • the second input signal is a frequency multiplexed signal from 1.0 to 2.1 GHz.
  • the multiplexer multiplexes the light phase-modulated by the optical phase modulator and the output light from the second light source.
  • the light receiving section optically heterodyne receives the output light multiplexed by the multiplexing section.
  • a broadband FM signal centered at a frequency equal to the frequency difference between the light from the first light source and the light from the second light source is obtained.
  • the light intensity modulator modulates the intensity of the output light from the third light source using the FM signal and outputs the modulated light. Since this method converts the input signal into a wideband FM signal all at once, it has excellent noise tolerance of the transmission path.
  • ITU-T J.185 Transmission equipment for transferring multi-channel television signals over optical access networks by frequency modulation conversion
  • International Telecommunication Union June 2012.
  • Toshiaki Shimoha Tomoaki Yoshida, Jun Terada, “Optical video distribution technology using FM batch conversion method”
  • Institute of Electronics, Information and Communication Engineers IEICE Technical Report CS2019-84, IE2019-64 (2019- 12), p.97-101
  • R. Miyatake, T. Shitaba, A. Tanabe, Y. Fukada, T. Yoshida "Optical transmission experiment on FM conversion method with wideband phase modulation," IEICE Communications Express, Vol.10, No.12, p.967- 972, 2021.
  • the above-mentioned FM batch conversion method requires two light sources to generate FM signals.
  • the oscillation frequencies of these light sources fluctuate randomly over time. Therefore, a certain phase noise occurs in the FM signal output from the light receiving section. As a result, the possible transmission distance is limited.
  • an object of the present invention is to provide an optical transmitter and an optical signal generation method that can perform FM conversion with low noise.
  • An optical transmission device includes an optical comb generator that generates an optical signal in which optical combs are arranged at equal frequency intervals using output light from a first light source and a frequency from a signal source; an extraction unit that extracts a first optical comb and a second optical comb from the optical signal generated by the optical comb generator; and a phase modulation unit that generates a modulation signal by phase modulating the first optical comb with an input signal.
  • an adjustment unit that adjusts the delay amount of the second optical comb; a multiplexing unit that multiplexes the modulated signal and the second optical comb whose delay amount has been adjusted; It includes a light receiving section that performs square law detection of the combined light to generate an FM (Frequency Modulation) signal, and a light intensity modulation section that intensity modulates the output light of the second light source using the FM signal.
  • FM Frequency Modulation
  • An optical signal generation method includes an optical comb generation step of generating an optical signal in which optical combs are arranged at equal frequency intervals using output light from a first light source and a frequency from a signal source; an extraction step of extracting a first optical comb and a second optical comb from the optical signal generated in the optical comb generation step; and a phase modulation step of generating a modulation signal by phase-modulating the first optical comb with an input signal.
  • the method includes a signal generation step of square-law detection of the light multiplexed in the step to generate an FM (Frequency Modulation) signal, and a light intensity modulation step of intensity modulating the output light of the second light source using the FM signal.
  • FM Frequency Modulation
  • the present invention enables FM conversion with low noise.
  • FIG. 1 is a block diagram showing the configuration of an optical transmitter according to an embodiment of the present invention.
  • 1 is a diagram showing a conventional optical video distribution system.
  • FIG. 1 is a block diagram showing the configuration of a conventional optical transmitter.
  • the present embodiment relates to an optical transmitter of an optical transmission system that employs an FM batch conversion method.
  • the FM batch conversion method input signals are collectively converted into a wideband FM signal, and then the optical signal is intensity-modulated using the wideband FM signal and output. Since the optical transmitter of this embodiment requires only one light source to generate the FM signal, it is possible to suppress the phase noise of the FM signal to a level lower than that of the prior art. Therefore, it is possible to realize a low-noise optical transmitter.
  • FIG. 1 is a functional block diagram of an optical transmitter 1 according to an embodiment of the present invention.
  • the optical transmitter 1 includes a first light source 11, an optical comb generator 12, a signal source 13, a distribution section 14, a first band limiter 15, a phase modulator 16, a second band limiter 17, and a second band limiter 17. , an optical path length adjustment section 18, a multiplexing section 19, a light receiving section 20, a light intensity modulation section 21, and a second light source 22.
  • the optical path including the first band limiting section 15 and the phase modulating section 16 is referred to as the first optical path
  • the optical path including the second band limiting section 17 and the optical path length adjusting section is referred to as the first optical path.
  • the optical path including 18 will be referred to as a second optical path.
  • the first light source 11 outputs light of a single frequency.
  • the output light from the first light source 11 is input to the optical comb generator 12 .
  • the optical comb generator 12 converts the light input from the first light source 11 into an optical signal in which optical spectra are arranged at equal intervals at the frequency output from the signal source 13.
  • the optical comb is an optical spectrum of each frequency arranged at equal intervals.
  • the optical comb generator 12 generally has a structure in which an optical modulator is inserted into an optical resonator, and generates a plurality of sideband waves with a frequency interval equal to the frequency of a modulation signal input to the optical modulator. It is a device that generates The modulated signal input to the optical modulator corresponds to the signal output from the signal source 13.
  • the distribution unit 14 inputs the optical signal converted by the optical comb generator 12.
  • the distribution unit 14 divides the input optical signal into two, outputs one optical signal to the first band limiting unit 15 on the first optical path, and outputs the other optical signal to the second band limiting unit 17 on the second optical path. Output.
  • the first band limiting unit 15 receives the optical signal from the distribution unit 14 and extracts a specific optical comb from the plurality of optical combs included in the input optical signal. That is, the first band limiting section 15 extracts one optical comb of a predetermined frequency. The first band limiting section 15 outputs the extracted optical comb to the phase modulation section 16 and does not output other optical combs.
  • the phase modulation unit 16 phase-modulates the optical comb input from the first band limiting unit 15 using an input electrical signal.
  • the input signal may be a signal at one frequency or may include multiple signals at different frequencies.
  • the input signal may be a signal obtained by combining a frequency multiplexed signal of 90 to 770 Hz and a frequency multiplexed signal of 1.0 to 2.1 GHz.
  • the second band limiter 17 receives the optical signal from the distributor 14 and extracts a specific optical comb different from the first band limiter 15 from the plurality of optical combs included in the input optical signal. That is, the second band limiter 17 extracts one optical comb having a predetermined frequency different from the frequency of the optical comb extracted by the first band limiter 15. The second band limiting section 17 outputs the extracted optical comb to the optical path length adjusting section 18 and does not output other optical combs.
  • the optical path length adjustment unit 18 has a predetermined optical path length, and the second band limiter 17 outputs an output so that the amount of delay of the optical signal on the second optical path is equal to the amount of delay of the optical signal on the first optical path. Adjust the delay amount of the optical comb. This is mainly because a delay occurs due to the optical path length of the phase modulation section 16. A value measured in advance can be used as the amount of delay to be adjusted.
  • the optical path length adjustment section 18 outputs the optical comb whose delay amount has been adjusted to the multiplexing section 19 .
  • the multiplexer 19 multiplexes the optical signal phase-modulated by the phase modulator 16 and the optical signal input from the optical path length adjuster 18, and outputs the optical signal obtained by the multiplexer to the light receiver 20.
  • the optical signal input from the optical path length adjustment section 18 is an optical comb whose delay amount has been adjusted.
  • the light receiving unit 20 performs square law detection of the optical signal input from the multiplexing unit 19, and detects a frequency centered at a frequency equal to the frequency difference between the two combined optical signals, that is, the frequency difference between the first optical comb and the second optical comb. It is converted into a wideband FM signal.
  • the light receiving section 20 outputs a wideband FM signal to the optical intensity modulating section 21 .
  • the light intensity modulation section 21 intensity-modulates the output light from the second light source 22 using the broadband FM signal input from the light receiving section 20.
  • the optical intensity modulator 21 outputs an intensity-modulated optical signal to a transmission path.
  • the optical transmitter 1 described above reduces the number of light sources conventionally required for FM signal generation from two to one. Since one light source is used, phase noise degradation due to temporal fluctuations in the oscillation frequency of the light source is extremely small. Therefore, it is possible to suppress the phase noise of the FM signal at the output of the light receiving section to be lower than before, and to realize an optical transmitter with lower noise than the conventional system. Because the noise is low, optical signals can be transmitted over longer distances than conventional systems.
  • the optical transmission device includes an optical comb generator, an extraction section, a phase modulation section, an adjustment section, a multiplexing section, a light receiving section, and a light intensity modulation section.
  • the optical comb generator generates an optical signal in which optical combs are arranged at equal frequency intervals using the output light from the first light source and the frequency from the signal source.
  • the extractor extracts the first optical comb and the second optical comb from the optical signal generated by the optical comb generator.
  • the phase modulation section generates a modulation signal by phase modulating the first optical comb with an input signal.
  • the input signal may be a non-multiplexed signal or a frequency multiplexed signal.
  • the adjustment unit adjusts the amount of delay of the second optical comb.
  • the adjustment section corresponds to, for example, the optical path length adjustment section 18 of the embodiment.
  • the multiplexing unit multiplexes the modulated signal and the second optical comb whose delay amount has been adjusted.
  • the light receiving section performs square law detection of the light multiplexed by the multiplexing section to generate an FM (Frequency Modulation) signal.
  • the light intensity modulation section intensity-modulates the output light of the second light source using the FM signal.
  • the extraction section may include a distribution section, a first extraction section, and a second extraction section.
  • the distribution section divides the optical signal generated by the optical comb generator into two parts.
  • the first extraction section extracts the first optical comb from one of the optical signals distributed by the distribution section.
  • the second extraction section extracts a second optical comb from the other optical signal distributed by the distribution section.
  • the first extractor corresponds to the first band limiter 15 of the embodiment
  • the second extractor corresponds to the second band limiter 17 of the embodiment.
  • Optical transmitter 11 First light source 12
  • Optical comb generator 13 Signal source 14
  • Distribution section 15 First band limiter 16
  • Second band limiter 18 Optical path length adjuster 19
  • Multiplexer 20 Light receiver 21
  • Light intensity Modulation section 22 Second light source

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)

Abstract

Selon la présente invention, un générateur de peigne optique utilise une lumière de sortie provenant d'une première source de lumière et une fréquence provenant d'une source de signal et génère un signal optique dans lequel des peignes optiques sont alignés côte à côte à des intervalles de fréquence égaux entre eux. Une unité d'extraction extrait un premier peigne optique et un second peigne optique à partir d'un signal optique généré par le générateur de peigne optique. Une unité de modulation de phase génère un signal modulé obtenu par modulation de phase du premier peigne optique en réponse à un signal d'entrée. Une unité de réglage règle la quantité de retard du second peigne optique. Une unité de multiplexage multiplexe le signal modulé et le second peigne optique dont la quantité de retard a été ajustée. Une unité de réception de lumière effectue une détection de loi quadratique sur la lumière multiplexée par l'unité de multiplexage et génère un signal de modulation de fréquence (FM). Une unité de modulation d'intensité optique module l'intensité de la lumière de sortie d'une seconde source de lumière en réponse au signal FM.
PCT/JP2022/031807 2022-08-24 2022-08-24 Dispositif de transmission optique et procédé de génération de signal optique WO2024042630A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010245752A (ja) * 2009-04-03 2010-10-28 Nippon Telegr & Teleph Corp <Ntt> 光／無線伝送装置
JP2019191344A (ja) * 2018-04-24 2019-10-31 アンリツ株式会社 位相特性校正装置及び位相特性校正方法
JP2021129208A (ja) * 2020-02-13 2021-09-02 Kddi株式会社 変調装置、変調システム及び光送信装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010245752A (ja) * 2009-04-03 2010-10-28 Nippon Telegr & Teleph Corp <Ntt> 光／無線伝送装置
JP2019191344A (ja) * 2018-04-24 2019-10-31 アンリツ株式会社 位相特性校正装置及び位相特性校正方法
JP2021129208A (ja) * 2020-02-13 2021-09-02 Kddi株式会社 変調装置、変調システム及び光送信装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
K. KIKUSHIMA ; H. YOSHINAGA ; H. NAKAMOTO ; C. KISHIMOTO ; M. KAWABE ; K. SUTO ; K. KUMOZAKI ; N. SHIBATA: "A Super Wideband Optical FM Modulation Scheme for Video Transmission Systems", IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, IEEE SERVICE CENTER, PISCATAWAY., US, vol. 14, no. 6, 1 August 1996 (1996-08-01), US , pages 1066, XP011401630, ISSN: 0733-8716, DOI: 10.1109/49.508278 *

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