Chromatic dispersion compensation module

A chromatic dispersion compensation module comprising,

• an enclosure (49) including an input terminal (41) and an output terminal (42),
• a chromatic dispersion compensation optical line (40) situated inside the enclosure and connecting the input terminal to the output terminal, the line comprising one or more chromatic dispersion compensation single-mode optical fibers (43, 45) in series and not comprising any HOM multimode optical fiber,
• the module being adapted to be inserted by means of the input and output terminals into a transmission line comprising a non-zero dispersion at 1550 nm single-mode dispersion shifted line optical fiber adapted to transmit information in a spectral domain of use,
• the input terminal introducing into the transmission line an input loss Γin expressed in dB,
• the output terminal introducing into the transmission line an output loss Γout expressed in dB,
• additional connections, if any, between compensation optical fibers together introducing into the transmission line a connection loss Γinter expressed in dB,
• the compensation optical fiber or the set of compensation optical fibers in series having, at a wavelength of 1550 nm, a plurality of average parameters including an average coefficient of attenuation αDCF expressed in dB/km, a negative average chromatic dispersion DDCF expressed in ps/nm-km, a negative average dispersion slope SDCF expressed in ps/nm2-km, an average chromatic dispersion to dispersion slope ratio DDCF/SDCF expressed in nm, an average figure of merit FOMDCF defined as −DDCF/αDCF expressed in ps/nm-dB, an average effective area Aeff expressed in μm2, and an average second order coefficient n2 of the refractive index as a function of the intensity expressed in 10−20 m2/W,
• the average chromatic dispersion to dispersion slope ratio being the ratio between the average chromatic dispersion and the average dispersion slope,
• the average figure of merit being the negative of the ratio between the average chromatic dispersion and the average coefficient of attenuation,
• the average coefficient of attenuation in the case of a single compensation optical fiber being lumped with the corresponding coefficient of attenuation of said single compensation optical fiber and in the case of a set of compensation optical fibers in series, the average coefficient of attenuation is equal to the sum of the corresponding attenuation coefficients of the various compensation optical fibers weighted by their respective contributions to the total series length of the compensation optical fibers plus the ratio of the connection loss divided by said total length,
• each of said other average parameters in the case of a single compensation optical fiber being lumped with the corresponding parameter of said single compensation optical fiber and each of said other average parameters in the case of a set of compensation optical fibers in series being the arithmetic mean of the corresponding parameters of the various compensation optical fibers when weighted by the respective lengths of said various compensation optical fibers,
• the module having insertion losses IL expressed in dB, where
• IL
• =
• D
• DCM
• D
• DCF
• ·
• α
• DCF
• +
• Γ
• in
• +
• Γ
• out
• and where DDCM=−680 ps/nm,
• the module having a non-linearity criterion NLC representing the effects of the non-linear phase and expressed in 10−6 km/W-dB, where
• NLC
• =
• 100
• ·
• n
• 2
• ·
• (
• 1
• -
• 10
• D
• DCM
• 10
• ·
• FOM
• DCF
• )
• A
• eff
• ·
• α
• DCF
• ·
• 10
• Γ
• in
• 10
• ,
• the module having a quality criterion CQ expressed in dB,
• where CQ=IL+10log NLC,
• the module having a quality-to-price ratio criterion CQ2 expressed in dB,
• where CQ2=CQ+Blog(FOMDCF)
• and where B=23,
• and the compensation optical fiber or the set of compensation optical fibers in series having,
• firstly, average chromatic dispersion more negative than −115 ps/nm-km, and
• secondly, for a given average figure of merit, average attenuation sufficiently high for the quality criterion to be less than 18 dB and the quality-to-price ratio criterion to be less than 66.6 dB.

A method of designing a chromatic dispersion compensation module,

• said module being adapted to comprise,
• an enclosure including an input terminal and an output terminal,
• a chromatic dispersion compensation optical line situated inside the enclosure and connecting the input terminal to the output terminal, the line comprising one or more chromatic dispersion compensation single-mode optical fibers in series and not comprising any HOM multimode optical fiber,
• said module being adapted to be inserted by means of the input and output terminals into a transmission line comprising a single-mode line optical fiber adapted to transmit information in a spectral domain of use,
• the input terminal introducing into the transmission line an input loss Γin expressed in dB,
• the output terminal introducing into the transmission line an output loss Γout expressed in dB,
• additional connections, if any, between compensation optical fibers together introducing into the transmission line a connection loss Γinter expressed in dB,
• the compensation optical fiber or the set of compensation optical fibers in series having, at a wavelength of 1550 nm, a plurality of average parameters including an average coefficient of attenuation αDCF expressed in dB/km, a negative average chromatic dispersion DDCF expressed in ps/nm-km, a negative average dispersion slope SDCF expressed in ps/nm2-km, an average chromatic dispersion to dispersion slope ratio DDCF/SDCF expressed in nm, an average figure of merit FOMDCF defined as −DDCF/αDCF expressed in ps/nm-dB, an average effective area Aeff expressed in μm2, and an average second order coefficient n2 of the refractive index as a function of the intensity expressed in 10−20 m2/W,
• the average chromatic dispersion to dispersion slope ratio being the ratio between the average chromatic dispersion and the average dispersion slope,
• the average figure of merit being the negative of the ratio between the average chromatic dispersion and the average coefficient of attenuation,
• the average coefficient of attenuation in the case of a single compensation optical fiber being lumped with the corresponding coefficient of attenuation of said single compensation optical fiber and in the case of a set of compensation optical fibers in series, the average coefficient of attenuation is equal to the sum of the corresponding attenuation coefficients of the various compensation optical fibers weighted by their respective contributions to the total series length of the compensation optical fibers plus the ratio of the connection loss divided by said total length,
• each of said other average parameters in the case of a single compensation optical fiber being lumped with the corresponding parameter of said single compensation optical fiber and each of said other average parameters in the case of a set of compensation optical fibers in series being the arithmetic mean of the corresponding parameters of the various compensation optical fibers when weighted by the respective lengths of said various compensation optical fibers,
• said module being adapted to have insertion losses IL expressed in dB, where
• IL
• =
• D
• DCM
• D
• DCF
• ·
• α
• DCF
• +
• Γ
• in
• +
• Γ
• out
• and where DDCM represents the negative of the cumulative dispersion of the line optical fiber,
• said module being adapted to have a non-linearity criterion NLC representing the effects of the non-linear phase and expressed in 10−6 km/W-dB, where
• NLC
• =
• 100
• ·
• n
• 2
• ·
• (
• 1
• -
• 10
• D
• DCM
• 10
• ·
• FOM
• DCF
• )
• A
• eff
• ·
• α
• DCF
• ·
• 10
• Γ
• in
• 10
• ,
• said module being adapted to have a quality criterion CQ expressed in dB,
• where CQ=IL+10log NLC,
• said design method including an optimization step for optimizing said module, said optimization step consisting in reducing the quality criterion at a chosen constant average figure of merit by increasing the average attenuation.