Effect of lower and upper parabolic dips in refractive index profile on performance of coaxial fiber Raman gain amplifier

doi:10.1117/1.OE.55.3.036103

Journal Article•DOI•

Effect of lower and upper parabolic dips in refractive index profile on performance of coaxial fiber Raman gain amplifier

Anup Karak¹, Sanchita Pramanik², Sanchita Pramanik¹, Somenath Sarkar¹•Institutions (2)

University of Calcutta¹, Vidyasagar University²

01 Mar 2016-Optical Engineering (International Society for Optics and Photonics)-Vol. 55, Iss: 3, pp 036103-036103

TL;DR: In this paper, the effect of practically possible upper and lower parabolic dips in the refractive index profile of the inner core of the coaxial fiber Raman gain amplifier is reported using matrix method for single pump.

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Abstract: An investigation on the effect of practically possible upper and lower parabolic dips in the refractive index profile of the inner core of the coaxial fiber Raman gain amplifier is reported using matrix method for single pump. It is seen that for lower parabolic dip, the tolerable limits of dip parameters correspond to dip depth of 0.25% and dip width of 25% of the respective parameters for ideal step index profile case and agree with the earlier predicted linear dip. However, for upper parabolic dip, one gets higher gain and better flatness at these limits. Even up to 1% of the dip depth for 25% of dip width or 75% of dip width for 0.25% of the dip depth or 0.5% of dip depth and 50% of dip width, one can expect performance as good as that of the ideal one. However, since system designers will be aimed to produce ideal profile, our recommendation is to keep tolerable limits within 0.25% of dip depth and 25% of dip width of respective parameters. But one can accept profile with upper parabolic dip if there is deviation within the above relaxation limits for such dip.

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Journal Article•DOI•

Dispersion-Compensating Fiber Raman Amplifiers With Step, Parabolic, and Triangular Refractive Index Profiles

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A.C.O. Chan¹, Malin Premaratne¹•Institutions (1)

Monash University, Clayton campus¹

30 Apr 2007-Journal of Lightwave Technology

TL;DR: In this paper, the performance of a gain-flattened coaxial fiber Raman amplifier with respect to the refractive index profile is analyzed, and the analysis shows that the dispersion coefficient is sensitive to the variation of the core structure of the fiber.

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Abstract: This paper presents a comprehensive analysis of the performance of a gain-flattened coaxial fiber Raman amplifier with respect to the refractive index profile. The variation of the dispersion coefficient and the end-end gain spectrum of the coaxial fiber Raman amplifier against the core structure as a function of the step, parabolic, and triangular profiles are analyzed. The analysis shows that the dispersion coefficient is sensitive to the variation of the core structure of the fiber, whereas the effective Raman gain coefficient remains nearly constant as the structure changes. Simulations of transmissions employing the coaxial fiber Raman amplifier with the three different structures are carried out individually, and the results show that the parabolic and triangular profiles perform better than the step profile, where the parabolic profile gives the best performance over 80 km of G.652 fiber, with a transmission rate of 20 Gb/s and a gain ripple of plusmn1 dB. In addition, the analysis shows that the maximum negative dispersion wavelength of the fiber exhibits a linear relationship with the normalized core radius. Hence, a coaxial fiber Raman amplifier providing a possible operation over the L-band is proposed

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23 citations

"Effect of lower and upper parabolic..." refers background in this paper

...However, the change in fiber profile structure can be considered for this purpose.(2,3,19) Now, among all the FRGA structures, coaxial fiber structure improves the system optimistically as it can provide larger bandwidth....
[...]
...Various investigations have already been carried out to obtain gain performances and dispersion coefficient of FRGA.(2,3) But, during the fiber drawing process, central burning in and around axial region is observed as an unavoidable problem even when one takes utmost care....
[...]
...The coaxial structure consists of two cores, namely inner and outer cores.(3,4) Using this structure, with single pump wavelength, one can obtain large bandwidth (∼90 nm)....
[...]
...However, with proper choice of pump wavelength below PMW, one can obtain a flat gain spectrum as a small effective area that results due to tight modal confinement.4,5,7 In FRGA, the study on effect of dip depth and dip width for LD in RIP is published currently showing how they affect the PMW, effective Raman gain coefficient, and dispersion coefficient, accordingly.5 However, no such work is available in connection with the study of the effect of practically possible lower parabolic dips (LPD) and upper parabolic dips (UPD) in the RIPs of the inner core of the coaxial structure on PMW, effective Raman gain coefficient, and dispersion coefficient of FRGA....
[...]
...We present our studies on the effects of LPD and UPD first on PMW, and then on performance of effective Raman gain coefficient and dispersion coefficient of FRGA....
[...]

Journal Article•DOI•

Fiber design for broad-band gain-flattened Raman fiber amplifier

[...]

Krishna Thyagarajan¹, Charu Kakkar¹•Institutions (1)

Indian Institutes of Technology¹

01 Dec 2003-IEEE Photonics Technology Letters

TL;DR: In this paper, a novel fiber design which has inherently flattened effective Raman gain spectrum, with a relative 3-dB bandwidth of /spl sim/90 nm, is presented.

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Abstract: We report here a novel fiber design which has inherently flattened effective Raman gain spectrum, with a relative 3-dB bandwidth of /spl sim/90 nm. Gain-flattened broad-band amplification can be achieved in any wavelength band by suitably choosing the fiber parameters and the pump wavelength. Simulations show that the proposed fiber also has high negative dispersion coefficient /spl sim/(-300 to -600) ps/km /spl middot/ nm in the operating range of wavelength. Hence, the designed fiber serves the purpose of a gain-flattened broad-band amplifier and dispersion compensator.

...read moreread less

23 citations

"Effect of lower and upper parabolic..." refers background in this paper

...However, the change in fiber profile structure can be considered for this purpose.(2,3,19) Now, among all the FRGA structures, coaxial fiber structure improves the system optimistically as it can provide larger bandwidth....
[...]
...Various investigations have already been carried out to obtain gain performances and dispersion coefficient of FRGA.(2,3) But, during the fiber drawing process, central burning in and around axial region is observed as an unavoidable problem even when one takes utmost care....
[...]
...However, with proper choice of pump wavelength below PMW, one can obtain a flat gain spectrum as a small effective area that results due to tight modal confinement.4,5,7 In FRGA, the study on effect of dip depth and dip width for LD in RIP is published currently showing how they affect the PMW, effective Raman gain coefficient, and dispersion coefficient, accordingly.5 However, no such work is available in connection with the study of the effect of practically possible lower parabolic dips (LPD) and upper parabolic dips (UPD) in the RIPs of the inner core of the coaxial structure on PMW, effective Raman gain coefficient, and dispersion coefficient of FRGA....
[...]
...We present our studies on the effects of LPD and UPD first on PMW, and then on performance of effective Raman gain coefficient and dispersion coefficient of FRGA....
[...]
...Therefore, the investigation appears to be technically meaningful in the study of FRGA....
[...]

Journal Article•DOI•

Novel fiber design for flat gain Raman amplification using single pump and dispersion compensation in S band

[...]

Krishna Thyagarajan¹, Charu Kakkar¹•Institutions (1)

Indian Institutes of Technology¹

08 Oct 2004-Journal of Lightwave Technology

TL;DR: In this paper, a novel fiber design that has an inherently flattened effective Raman gain spectrum is reported, which can serve as a lossless, broad-band, dispersion-flattening, and dispersioncompensating module for the S band, wherein lossless operation is achieved using inherently gain-flatened single-pump Raman amplification.

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Abstract: This paper reports on a novel fiber design that has an inherently flattened effective Raman gain spectrum Simulations show that gain-flattened broad-band Raman amplification, using a single pump, can be achieved in any wavelength band by suitably choosing the fiber parameters and the pump wavelength The fiber also has a high negative dispersion coefficient-(380-515) ps/km/spl middot/nm over the operating range of wavelengths-and the shape of the dispersion curve is such that the total link dispersion can be not only compensated but also flattened Hence, the designed fiber can serve as a lossless, broad-band, dispersion-flattening, and dispersion-compensating module for the S band, wherein lossless operation is achieved using inherently gain-flattened single-pump Raman amplification The performance characteristics of such a module was modeled taking into account wavelength-dependent splice loss as well as background loss, and it has been shown through simulations that lossless operation with /spl plusmn/02-dB gain ripple is achievable over (1480-1511) nm using a single pump Moreover, dispersion compensation for five spans of transmission in a 10-Gb/s system, over this 32-nm bandwidth in the S band, should be attainable using the proposed design

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19 citations

"Effect of lower and upper parabolic..." refers background or methods in this paper

...However, with proper choice of pump wavelength below PMW, one can obtain a flat gain spectrum as a small effective area that results due to tight modal confinement.(4,5,7) In FRGA, the study on effect of dip depth and dip width for LD in RIP is published currently showing how they affect the PMW, effective Raman gain coefficient, and dispersion coefficient, accordingly....
[...]
...The coaxial structure consists of two cores, namely inner and outer cores.(3,4) Using this structure, with single pump wavelength, one can obtain large bandwidth (∼90 nm)....
[...]
...Also, large negative dispersion is crucial for flattening of total link dispersion in FRGA throughout operating region and it can be obtained using this fiber structure.(4,18) Various investigations have already been carried out to obtain gain performances and dispersion coefficient of FRGA....
[...]

Journal Article•DOI•

Comparative study of the influence of the aspect ratio of trapezoidal index profiles on the performance of a fiber Raman amplifier

[...]

Sanchita Pramanik¹, Gautam Das², Somenath Sarkar¹•Institutions (2)

University of Calcutta¹, Lakehead University²

01 May 2010-Optical Engineering

TL;DR: In this paper, the effect of aspect ratios of trapezoidal index profiles in the inner core on the Raman gain was investigated in the context of a single-mode Raman amplifier.

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Abstract: We have sought a suitable coaxial refractive index profile with dispersion-flattened and dispersion-shifted criteria in the context of a single-mode Raman gain amplifier. We present a novel comparative study based on the effective core area and Raman gain coefficient in relation to the effect of aspect ratios of trapezoidal index profiles in the inner core on the Raman gain.

...read moreread less

16 citations

"Effect of lower and upper parabolic..." refers background in this paper

...However, the change in fiber profile structure can be considered for this purpose.(2,3,19) Now, among all the FRGA structures, coaxial fiber structure improves the system optimistically as it can provide larger bandwidth....
[...]

Journal Article•DOI•

Effect of axial refractive-index dip on zero total dispersion wavelength in single-mode fibres

[...]

Bishnu P. Pal¹, Anil Kumar¹, Ajoy Ghatak¹•Institutions (1)

Indian Institutes of Technology¹

19 Jun 1980-Electronics Letters

TL;DR: In this paper, the effect of axial refractive index dip on the dispersion characteristics of high-silica optical fibres has been investigated in terms of the total dispersion wavelength λ 0 in a single-mode fiber.

...read moreread less

Abstract: The effect of the axial refractive-index dip, which is a characteristic of c.v.d. high-silica optical fibres, on the dispersion characteristics of single-mode fibres is studied. In particular, the effect of a Gaussian dip on zero total dispersion wavelength λ0 in a single-mode fibre is investigated. The dip is found, in general, to shift λ0 to a wavelength shorter than that in the absence of the dip for the same fibre.

...read moreread less

13 citations

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Effect of lower and upper parabolic dips in refractive index profile on performance of coaxial fiber Raman gain amplifier

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