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WO2013011549A1 - Démodulateur optique - Google Patents

Démodulateur optique Download PDF

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Publication number
WO2013011549A1
WO2013011549A1 PCT/JP2011/066263 JP2011066263W WO2013011549A1 WO 2013011549 A1 WO2013011549 A1 WO 2013011549A1 JP 2011066263 W JP2011066263 W JP 2011066263W WO 2013011549 A1 WO2013011549 A1 WO 2013011549A1
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WO
WIPO (PCT)
Prior art keywords
optical
optical signals
pair
fixed delay
delay adjustment
Prior art date
Application number
PCT/JP2011/066263
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English (en)
Japanese (ja)
Inventor
勇貴 金原
宮地　正英
日隈　薫
利夫 片岡
Original Assignee
住友大阪セメント株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 住友大阪セメント株式会社 filed Critical 住友大阪セメント株式会社
Priority to PCT/JP2011/066263 priority Critical patent/WO2013011549A1/fr
Publication of WO2013011549A1 publication Critical patent/WO2013011549A1/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
    • H04B10/60—Receivers
    • H04B10/66—Non-coherent receivers, e.g. using direct detection
    • H04B10/67—Optical arrangements in the receiver
    • H04B10/676—Optical arrangements in the receiver for all-optical demodulation of the input optical signal
    • H04B10/677—Optical arrangements in the receiver for all-optical demodulation of the input optical signal for differentially modulated signal, e.g. DPSK signals

Definitions

  • the present invention relates to an optical demodulator, and more particularly to an optical demodulator in a communication system that uses a phase change as a modulation signal, such as a DQPSK modulation system.
  • DQPSK modulation differential quadrature phase shift keying
  • OOK binary intensity modulation
  • quadrature phase shift keying (QPSK modulation, quadrature phase shift) keying) method is “ ⁇ ”, “ ⁇ + ⁇ / 2”, “ ⁇ + ⁇ ”, and “ ⁇ + 3 ⁇ ” for each symbol “00”, “01”, “11”, and “10” composed of 2-bit data. / 2 "is assigned.
  • “ ⁇ ” is an arbitrary phase.
  • the demodulator reproduces the transmission data by detecting the phase of the received signal.
  • a DQPSK modulation method As a means for realizing the QPSK modulation method relatively easily, there is a DQPSK modulation method. In the DQPSK modulation, a carrier phase change amount (“0” between the value of the symbol transmitted first and the value of the symbol transmitted next). ”,“ ⁇ / 2 ”,“ ⁇ ”and“ 3 ⁇ / 2 ”) are associated with 2 bits of transmission information. Therefore, the receiver can recover the transmission data by detecting the phase difference between two adjacent symbols.
  • the interference type is a type in which incident light is divided into two optical paths and one of the optical paths is delayed by 1 bit and combined to generate interference according to the modulation phase before and after, and converted into the intensity of the emitted light It is.
  • the phase-polarization conversion type converts incident light into specific linearly polarized light, divides the linearly polarized light into two types of orthogonal polarization components, and multiplexes one of the changes with a delay of 1 bit. As a result, a polarization state corresponding to the front and rear modulation phases is generated and converted into the intensity of the emitted light.
  • the optical path length is further shifted by ⁇ / 4 ( ⁇ is the wavelength of light) for the light delayed by 1 bit
  • a linear polarization rotator such as a Faraday rotator is inserted after passing through a ⁇ / 4 plate having crystal axes orthogonal to I and Q, respectively.
  • an active control element 40 is arranged in each optical path of the digital signals I and Q.
  • the active control element is composed of a silicon plate or the like, and is configured so that the delay amount for each of the digital signals I and Q can be adjusted by applying heat.
  • the optical signal is branched into the object light and the reference light by the beam splitter 10 in FIG. 3, and for example, the light wave directed to the left is the object light, and the light wave directed upward is the reference light.
  • the object light is reflected by the prism mirror 20, passes through the active control element 4, and enters the beam splitter 10 again.
  • the other reference light is reflected by the prism mirror 30, enters the beam splitter again, is combined with the object light, and is output as an optical signal related to the digital signals I and Q.
  • the active control element 40 is controlled separately for each digital signal. For this reason, interference type control leads to generation of characteristic deterioration factors such as a complicated control system and thermal crosstalk (a phenomenon in which I control affects Q control).
  • the problem to be solved by the present invention is to solve the above-mentioned problems, and in an optical demodulator in a communication system that uses a phase change as a modulation signal, such as a DQPSK modulation system, the phase for each digital signal in the 1-bit delay portion
  • a phase change as a modulation signal
  • DQPSK modulation system the phase for each digital signal in the 1-bit delay portion
  • the invention according to claim 1 is configured such that an input differential phase shift keying optical signal is branched into a plurality of pairs of optical signals by a branching unit, and a predetermined amount is provided between the pair of optical signals. After the delay amount is given, the optical signal of the pair is multiplexed in the multiplexing unit, and based on the result obtained from the specific combination of the multiplexed optical signals, the differential phase shift keying optical signal
  • a fixed delay adjustment unit that provides a fixed delay amount corresponding to each pair between the optical signals of the pair is provided in at least one of the optical paths of the pair of optical signals.
  • a variable identical delay adjusting unit that gives the same delay amount is placed on one optical path of all pairs of optical signals provided with the fixed delay adjusting unit, or on the other optical path of all pairs of optical signals not provided with the fixed delay adjusting unit. It is provided.
  • variable identical delay adjusting unit configured by a single medium that adjusts a delay amount by transmitting one of all pairs of optical signals. It is characterized by that.
  • the amount of delay generated by the fixed delay adjustment unit in the other optical path of all pairs of optical signals not provided with the fixed delay adjustment unit A delay amount correction unit is provided, which has a delay amount corresponding to a minimum value and a maximum value of the same, and is made of the same medium as the fixed delay adjustment unit.
  • the input differential phase shift keying optical signal is branched into a plurality of pairs of optical signals at the branching section, and a predetermined delay amount is given between the pairs of optical signals.
  • An optical demodulator that combines the pair of optical signals at a multiplexing unit and demodulates the differential phase shift keying optical signal based on a result obtained from a specific combination of the combined optical signals.
  • a fixed delay adjustment unit that provides a fixed delay amount corresponding to each pair between the optical signals of the pair is provided in at least one of the optical paths of the pair of optical signals to provide a variable and the same delay amount.
  • the active control element The adjustment unit that is variable when adjusting the amount of delay Becomes "only, there is no need to use a plurality of active control elements as in the prior art. As a result, it is possible to suppress characteristic deterioration due to thermal crosstalk between active control elements and characteristic deterioration due to characteristic variations between active control elements such as a Faraday rotator.
  • variable identical delay adjustment unit is configured by a single medium that adjusts the delay amount by transmitting one of the optical signals of all pairs, so that thermal crosstalk and variations between elements are reduced. It becomes possible to eliminate it reliably.
  • the number of optical components can be reduced, an increase in manufacturing cost can be suppressed, and the work burden required for product assembly can be reduced.
  • a delay amount corresponding to at least the minimum value and not more than the maximum value of the delay amount generated in the fixed delay adjustment unit is provided on the other optical path of the optical signals of all pairs not provided with the fixed delay adjustment unit. Since the delay amount correction unit made of the same medium as the fixed delay adjustment unit is provided, even if the delay amount of the fixed delay adjustment unit changes due to environmental temperature change or wavelength dependency, the delay amount in the delay amount correction unit Change in the same manner, so that the change in the phase difference between the optical signals of each pair is suppressed.
  • the optical demodulator of the present invention branches an input differential phase shift keyed optical signal into a plurality of pairs of optical signals at a branching unit 10, and between the pairs of optical signals. After giving a predetermined delay amount, the optical signal of the pair is multiplexed by the multiplexing unit 10, and based on the result obtained from a specific combination of the multiplexed optical signals (I and Q output signals)
  • the fixed delay adjustment unit 42 that gives a fixed delay amount corresponding to each pair between the pair of optical signals is provided with at least a part of the pair of optical signals.
  • a variable identical delay adjustment unit 41 that is provided in one optical path of a signal and gives a variable and same delay amount is provided in one optical path of all pairs of optical signals provided with the fixed delay adjustment unit, or the fixed delay adjustment unit. It is characterized in that it is provided in the other optical path of all pairs of optical signals.
  • the active control element is only the variable identical delay adjustment unit, it is possible to suppress characteristic deterioration due to the active control element, unlike the case where an active control element is provided for each conventional optical signal. Specifically, since there is only one active control element, the interference type optical demodulator does not cause a problem of thermal crosstalk between the active control elements. In the phase-polarization conversion type, there is no variation in characteristics between active control elements such as a Faraday rotator.
  • variable identical delay adjustment unit is constituted by a single medium that adjusts the delay amount by transmitting one of all pairs of optical signals, such as a single silicon plate or a single Faraday rotator.
  • the optical demodulator of the present invention includes a fixed delay adjustment unit 42. This is for adjusting the phase difference between the object light and the reference light for each optical signal (I, Q).
  • a transparent plate such as a quartz glass plate is used as the phase compensation plate 42.
  • the thickness of the phase compensation plate to be arranged may be changed for each optical signal, but can also be set to have the same thickness from the viewpoint of sharing parts. Then, adjustment is performed by inclining the angle of the phase compensator with respect to the optical axis so that the phase difference between the object light and the reference light becomes a predetermined value for each optical signal (I, Q).
  • an optical system from the branching part to the multiplexing part of the optical path is not only formed by a spatial optical system using a beam splitter and a reflecting prism as shown in FIG. It is also possible to configure the optical waveguide.
  • the effective refractive index can be changed by applying an adhesive to the upper portion of the optical waveguide or laser trimming a part of the optical waveguide as the phase correction means.
  • the application example of the optical demodulator of the present invention is the other optical path of all pairs of optical signals without the fixed delay adjustment unit 42 (the optical path formed by the beam splitter 10 and the reflecting prism 30).
  • a delay amount correction unit 43 having a delay amount corresponding to the minimum value and not more than the maximum value of the delay amount generated in the fixed delay adjustment unit and made of the same medium as the fixed delay adjustment unit is provided.
  • the delay amount correcting unit 43 is also the same. Since the phase changes, the phase difference between the optical signals of each pair (object light and reference light) is suppressed from changing. Thereby, it is possible to provide an optical demodulator having stable characteristics with respect to temperature change and the wavelength of the propagating light wave.
  • phase adjustment for each digital signal and polarization rotation angle adjustment in a 1-bit delay portion can be set with high accuracy, and an optical demodulator capable of suppressing deterioration of signal characteristics can be provided.

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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

La présente invention a pour but de pourvoir à un démodulateur optique pour le format de modulation par déplacement de phase à quatre états avec détection différentielle (MDPQD) ou un autre format de communication, qui utilise un changement de phase en tant que signal de modulation, le démodulateur optique pouvant fixer de façon hautement précise un ajustement de phase ou un ajustement d'angle de rotation de polarisation pour chaque signal numérique dans une partie retardée de 1 bit, et pouvant empêcher une détérioration de caractéristique de signal. L'invention est un démodulateur optique qui divise un signal optique de modulation de déphasage différentiel d'entrée en de multiples paires de signaux optiques au niveau d'un diviseur (10), combine les paires de signaux optiques (I et Q) au niveau d'un combineur (10) après fourniture d'une quantité de retard spécifiée entre chaque paire de signaux optiques, et démodule le signal optique de modulation de déphasage différentiel sur la base d'un résultat obtenu à partir d'une combinaison spécifique des signaux optiques combinés. L'invention est caractérisée en ce qu'elle comprend : une section d'ajustement de retard fixe (42) disposée sur l'un des chemins optiques d'au moins une paire de signaux optiques, ladite section d'ajustement de retard fixe (42) fournissant une quantité de retard fixe entre ladite paire de signaux optiques, et ladite quantité de retard fixe correspondant à la paire applicable dans chaque cas ; et une section d'ajustement de retard identique variable (41) qui fournit une quantité de retard identique variable, ladite section d'ajustement de retard identique variable (41) étant disposée sur l'un des chemins optiques de chaque paire de signaux optiques comprenant ladite section d'ajustement de retard fixe, ou sur l'autre chemin optique de chaque paire de signaux optiques ne comprenant pas ladite section d'ajustement de retard fixe.
PCT/JP2011/066263 2011-07-15 2011-07-15 Démodulateur optique WO2013011549A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP2011/066263 WO2013011549A1 (fr) 2011-07-15 2011-07-15 Démodulateur optique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2011/066263 WO2013011549A1 (fr) 2011-07-15 2011-07-15 Démodulateur optique

Publications (1)

Publication Number Publication Date
WO2013011549A1 true WO2013011549A1 (fr) 2013-01-24

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PCT/JP2011/066263 WO2013011549A1 (fr) 2011-07-15 2011-07-15 Démodulateur optique

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006287493A (ja) * 2005-03-31 2006-10-19 Fujitsu Ltd Ｍ相差分位相偏移変調方式に対応した光受信器
JP2006295603A (ja) * 2005-04-12 2006-10-26 Mitsubishi Electric Corp 光受信器

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006287493A (ja) * 2005-03-31 2006-10-19 Fujitsu Ltd Ｍ相差分位相偏移変調方式に対応した光受信器
JP2006295603A (ja) * 2005-04-12 2006-10-26 Mitsubishi Electric Corp 光受信器

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