Abstract

For applications in high-density and high-speed optical interconnections, we propose to utilize polymer parallel optical waveguides (PPOWs) with so-called W-shaped refractive index profile in the core area. A W-shaped index profile is composed of a parabolic index distribution surrounded by a narrow index valley, followed by a cladding with a uniform refractive index. We expect that W-shaped index profiles contribute to decreasing the inter-channel crosstalk due to mode conversion in the waveguides. In this paper, we investigate how much the index difference of the index valley improves the crosstalk value. First, we fabricate polymer waveguides with various index profiles by changing the composition of the copolymer for cladding. We show the results that a 1-m long W-shaped profile PPOW has not only low propagation loss (0.027 dB/cm), but an inter-channel crosstalk (~-40 dB) lower than those of graded index (GI) core PPOW we previously fabricated. Next, we theoretically analyze the propagation loss and inter-channel crosstalk in polymer waveguides with different index profiles by means of a ray tracing model in which the light scattering effect is included. The calculation results indicate that the index valley surrounding each core works properly for preventing the power coupling from the cladding modes to the propagation modes, and consequently, very low inter-channel crosstalk is realized with W-shaped index profiles.

© 2011 OSA

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. A. F. Benner, M. Ignatowski, J. A. Kash, D. M. Kuchta, and M. B. Ritter, “Exploitation of optical interconnects in future server architectures,” IBM J. Res. Develop. 49(4), 755–775 (2005), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5388810 .
    [CrossRef]
  2. N. Bamiedakis, J. Beals IV, R. V. Penty, I. H. White, J. V. DeGroot, Jr., and T. V. Clapp, “Cost-effective multimode polymer waveguides for high-speed on-board optical interconnects”, IEEE J. Quant. Electron., 45, 415 (2009), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4803864 .
  3. I. Papakonstantinou, D. R. Selviah, R. C. A. Pitwon, and D. Milward, “Low-cost, precision, self-alignment technique for coupling laser and photodiode arrays to polymer waveguide arrays on multilayer PCBs”, IEEE Trans. Advanced Packaging, 31, 502, (2008), http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4534823 .
  4. T. Ishigure and Y. Takeyoshi, “Polymer waveguide with 4-channel graded-index circular cores for parallel optical interconnects,” Opt. Express 15(9), 5843–5850 (2007), http://www.opticsinfobase.org/abstract.cfm?uri=oe-15-9-5843 .
    [CrossRef] [PubMed]
  5. Y. Takeyoshi and T. Ishigure, “High-density 2 X 4 channel polymer optical waveguide with graded-index circular cores,” J. Lightwave Technol. 27(14), 2852–2861 (2009), http://www.opticsinfobase.org/abstract.cfm?uri=jlt-27-14-2852 .
    [CrossRef]
  6. T. Ishigure and Y. Nitta, “Polymer optical waveguide with multiple graded-index cores for on-board interconnects fabricated using soft-lithography,” Opt. Express 18(13), 14191–14201 (2010), http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-18-13-14191 .
    [CrossRef] [PubMed]
  7. K. Okamoto and T. Okoshi, “Analysis of wave propagation in optical fibers having core with a-power refractive-index distribution and uniform cladding,” IEEE Trans. Microw. Theory Tech. 24(7), 416–421 (1976), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1128869 .
    [CrossRef]
  8. K. Okamoto and T. Okoshi, “Computer-Aided Synthesis of the Optimum Refractive-Index Profile for a Multimode Fiber,” IEEE Trans. Microw. Theory Tech. 25(3), 213–221 (1977), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1129073 .
    [CrossRef]
  9. K. Oyamada and T. Okoshi, “High-accuracy numerical data of propagation characteristics of a-power graded-core fibers,” IEEE Trans. Microw. Theory Tech. 28(10), 1113–1118 (1980), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1130234 .
    [CrossRef]
  10. D. Ðonlagi’c, “Opportunities to enhance multimode fiber links by application of overfilled launch,” J. Lightwave Technol. 23, 35264 (2005), http://www.opticsinfobase.org/abstract.cfm?uri=JLT-23-11-3526 .
    [CrossRef]
  11. T. Ishigure, H. Endo, K. Ohdoko, K. Takahashi, and Y. Koike, “Modal bandwidth enhancement in a plastic optical fiber by W-refractive index profile,” J. Lightwave Technol. 23(4), 1754–1762 (2005), http://www.opticsinfobase.org/abstract.cfm?uri=JLT-23-4-1754 .
    [CrossRef]
  12. K. Takahashi, T. Ishigure, and Y. Koike, “Index profile design for high-bandwidth W-shaped plastic optical fiber,” J. Lightwave Technol. 24(7), 2867–2876 (2006), http://www.opticsinfobase.org/abstract.cfm?uri=JLT-24-7-2867 .
    [CrossRef]
  13. Y. Takeyoshi and T. Ishigure, “Multichannel parallel polymer waveguide with circular W-shaped index profile cores,” IEEE Photon. Technol. Lett. 19(22), 1795–1797 (2007), http://ieeexplore.ieee.org/iel5/68/ 4351987/04367530.pdf?arnumber=4367530 .
    [CrossRef]
  14. H. H. Hsu and T. Ishigure, “High-density channel alignment of graded index core polymer optical waveguide and its crosstalk analysis with ray tracing method,” Opt. Express 18(13), 13368–13378 (2010), http://www.opticsinfobase.org/abstract.cfm?uri=oe-18-13-13368 .
    [CrossRef] [PubMed]
  15. H. M. Presby, W. Mammel, and R. M. Derosier, “Refractive index profiling of graded index optical fibers”, Rev. Sci. lnstrum., 47, 348 (1976), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=4981006 .
  16. A. W. Snyder and J. D. Love, Optical Waveguide Theory (Chapman & Hall, 1983), Chap. 7, http://goo.gl/k3Z9m .

2010

2009

2007

Y. Takeyoshi and T. Ishigure, “Multichannel parallel polymer waveguide with circular W-shaped index profile cores,” IEEE Photon. Technol. Lett. 19(22), 1795–1797 (2007), http://ieeexplore.ieee.org/iel5/68/ 4351987/04367530.pdf?arnumber=4367530 .
[CrossRef]

T. Ishigure and Y. Takeyoshi, “Polymer waveguide with 4-channel graded-index circular cores for parallel optical interconnects,” Opt. Express 15(9), 5843–5850 (2007), http://www.opticsinfobase.org/abstract.cfm?uri=oe-15-9-5843 .
[CrossRef] [PubMed]

2006

2005

D. Ðonlagi’c, “Opportunities to enhance multimode fiber links by application of overfilled launch,” J. Lightwave Technol. 23, 35264 (2005), http://www.opticsinfobase.org/abstract.cfm?uri=JLT-23-11-3526 .
[CrossRef]

T. Ishigure, H. Endo, K. Ohdoko, K. Takahashi, and Y. Koike, “Modal bandwidth enhancement in a plastic optical fiber by W-refractive index profile,” J. Lightwave Technol. 23(4), 1754–1762 (2005), http://www.opticsinfobase.org/abstract.cfm?uri=JLT-23-4-1754 .
[CrossRef]

A. F. Benner, M. Ignatowski, J. A. Kash, D. M. Kuchta, and M. B. Ritter, “Exploitation of optical interconnects in future server architectures,” IBM J. Res. Develop. 49(4), 755–775 (2005), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5388810 .
[CrossRef]

1980

K. Oyamada and T. Okoshi, “High-accuracy numerical data of propagation characteristics of a-power graded-core fibers,” IEEE Trans. Microw. Theory Tech. 28(10), 1113–1118 (1980), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1130234 .
[CrossRef]

1977

K. Okamoto and T. Okoshi, “Computer-Aided Synthesis of the Optimum Refractive-Index Profile for a Multimode Fiber,” IEEE Trans. Microw. Theory Tech. 25(3), 213–221 (1977), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1129073 .
[CrossRef]

1976

K. Okamoto and T. Okoshi, “Analysis of wave propagation in optical fibers having core with a-power refractive-index distribution and uniform cladding,” IEEE Trans. Microw. Theory Tech. 24(7), 416–421 (1976), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1128869 .
[CrossRef]

Benner, A. F.

A. F. Benner, M. Ignatowski, J. A. Kash, D. M. Kuchta, and M. B. Ritter, “Exploitation of optical interconnects in future server architectures,” IBM J. Res. Develop. 49(4), 755–775 (2005), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5388810 .
[CrossRef]

Ðonlagi’c, D.

D. Ðonlagi’c, “Opportunities to enhance multimode fiber links by application of overfilled launch,” J. Lightwave Technol. 23, 35264 (2005), http://www.opticsinfobase.org/abstract.cfm?uri=JLT-23-11-3526 .
[CrossRef]

Endo, H.

Hsu, H. H.

Ignatowski, M.

A. F. Benner, M. Ignatowski, J. A. Kash, D. M. Kuchta, and M. B. Ritter, “Exploitation of optical interconnects in future server architectures,” IBM J. Res. Develop. 49(4), 755–775 (2005), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5388810 .
[CrossRef]

Ishigure, T.

T. Ishigure and Y. Nitta, “Polymer optical waveguide with multiple graded-index cores for on-board interconnects fabricated using soft-lithography,” Opt. Express 18(13), 14191–14201 (2010), http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-18-13-14191 .
[CrossRef] [PubMed]

H. H. Hsu and T. Ishigure, “High-density channel alignment of graded index core polymer optical waveguide and its crosstalk analysis with ray tracing method,” Opt. Express 18(13), 13368–13378 (2010), http://www.opticsinfobase.org/abstract.cfm?uri=oe-18-13-13368 .
[CrossRef] [PubMed]

Y. Takeyoshi and T. Ishigure, “High-density 2 X 4 channel polymer optical waveguide with graded-index circular cores,” J. Lightwave Technol. 27(14), 2852–2861 (2009), http://www.opticsinfobase.org/abstract.cfm?uri=jlt-27-14-2852 .
[CrossRef]

T. Ishigure and Y. Takeyoshi, “Polymer waveguide with 4-channel graded-index circular cores for parallel optical interconnects,” Opt. Express 15(9), 5843–5850 (2007), http://www.opticsinfobase.org/abstract.cfm?uri=oe-15-9-5843 .
[CrossRef] [PubMed]

Y. Takeyoshi and T. Ishigure, “Multichannel parallel polymer waveguide with circular W-shaped index profile cores,” IEEE Photon. Technol. Lett. 19(22), 1795–1797 (2007), http://ieeexplore.ieee.org/iel5/68/ 4351987/04367530.pdf?arnumber=4367530 .
[CrossRef]

K. Takahashi, T. Ishigure, and Y. Koike, “Index profile design for high-bandwidth W-shaped plastic optical fiber,” J. Lightwave Technol. 24(7), 2867–2876 (2006), http://www.opticsinfobase.org/abstract.cfm?uri=JLT-24-7-2867 .
[CrossRef]

T. Ishigure, H. Endo, K. Ohdoko, K. Takahashi, and Y. Koike, “Modal bandwidth enhancement in a plastic optical fiber by W-refractive index profile,” J. Lightwave Technol. 23(4), 1754–1762 (2005), http://www.opticsinfobase.org/abstract.cfm?uri=JLT-23-4-1754 .
[CrossRef]

Kash, J. A.

A. F. Benner, M. Ignatowski, J. A. Kash, D. M. Kuchta, and M. B. Ritter, “Exploitation of optical interconnects in future server architectures,” IBM J. Res. Develop. 49(4), 755–775 (2005), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5388810 .
[CrossRef]

Koike, Y.

Kuchta, D. M.

A. F. Benner, M. Ignatowski, J. A. Kash, D. M. Kuchta, and M. B. Ritter, “Exploitation of optical interconnects in future server architectures,” IBM J. Res. Develop. 49(4), 755–775 (2005), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5388810 .
[CrossRef]

Nitta, Y.

Ohdoko, K.

Okamoto, K.

K. Okamoto and T. Okoshi, “Computer-Aided Synthesis of the Optimum Refractive-Index Profile for a Multimode Fiber,” IEEE Trans. Microw. Theory Tech. 25(3), 213–221 (1977), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1129073 .
[CrossRef]

K. Okamoto and T. Okoshi, “Analysis of wave propagation in optical fibers having core with a-power refractive-index distribution and uniform cladding,” IEEE Trans. Microw. Theory Tech. 24(7), 416–421 (1976), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1128869 .
[CrossRef]

Okoshi, T.

K. Oyamada and T. Okoshi, “High-accuracy numerical data of propagation characteristics of a-power graded-core fibers,” IEEE Trans. Microw. Theory Tech. 28(10), 1113–1118 (1980), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1130234 .
[CrossRef]

K. Okamoto and T. Okoshi, “Computer-Aided Synthesis of the Optimum Refractive-Index Profile for a Multimode Fiber,” IEEE Trans. Microw. Theory Tech. 25(3), 213–221 (1977), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1129073 .
[CrossRef]

K. Okamoto and T. Okoshi, “Analysis of wave propagation in optical fibers having core with a-power refractive-index distribution and uniform cladding,” IEEE Trans. Microw. Theory Tech. 24(7), 416–421 (1976), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1128869 .
[CrossRef]

Oyamada, K.

K. Oyamada and T. Okoshi, “High-accuracy numerical data of propagation characteristics of a-power graded-core fibers,” IEEE Trans. Microw. Theory Tech. 28(10), 1113–1118 (1980), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1130234 .
[CrossRef]

Ritter, M. B.

A. F. Benner, M. Ignatowski, J. A. Kash, D. M. Kuchta, and M. B. Ritter, “Exploitation of optical interconnects in future server architectures,” IBM J. Res. Develop. 49(4), 755–775 (2005), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5388810 .
[CrossRef]

Takahashi, K.

Takeyoshi, Y.

IBM J. Res. Develop.

A. F. Benner, M. Ignatowski, J. A. Kash, D. M. Kuchta, and M. B. Ritter, “Exploitation of optical interconnects in future server architectures,” IBM J. Res. Develop. 49(4), 755–775 (2005), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5388810 .
[CrossRef]

IEEE Photon. Technol. Lett.

Y. Takeyoshi and T. Ishigure, “Multichannel parallel polymer waveguide with circular W-shaped index profile cores,” IEEE Photon. Technol. Lett. 19(22), 1795–1797 (2007), http://ieeexplore.ieee.org/iel5/68/ 4351987/04367530.pdf?arnumber=4367530 .
[CrossRef]

IEEE Trans. Microw. Theory Tech.

K. Okamoto and T. Okoshi, “Analysis of wave propagation in optical fibers having core with a-power refractive-index distribution and uniform cladding,” IEEE Trans. Microw. Theory Tech. 24(7), 416–421 (1976), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1128869 .
[CrossRef]

K. Okamoto and T. Okoshi, “Computer-Aided Synthesis of the Optimum Refractive-Index Profile for a Multimode Fiber,” IEEE Trans. Microw. Theory Tech. 25(3), 213–221 (1977), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1129073 .
[CrossRef]

K. Oyamada and T. Okoshi, “High-accuracy numerical data of propagation characteristics of a-power graded-core fibers,” IEEE Trans. Microw. Theory Tech. 28(10), 1113–1118 (1980), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1130234 .
[CrossRef]

J. Lightwave Technol.

Opt. Express

Other

H. M. Presby, W. Mammel, and R. M. Derosier, “Refractive index profiling of graded index optical fibers”, Rev. Sci. lnstrum., 47, 348 (1976), http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=4981006 .

A. W. Snyder and J. D. Love, Optical Waveguide Theory (Chapman & Hall, 1983), Chap. 7, http://goo.gl/k3Z9m .

N. Bamiedakis, J. Beals IV, R. V. Penty, I. H. White, J. V. DeGroot, Jr., and T. V. Clapp, “Cost-effective multimode polymer waveguides for high-speed on-board optical interconnects”, IEEE J. Quant. Electron., 45, 415 (2009), http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4803864 .

I. Papakonstantinou, D. R. Selviah, R. C. A. Pitwon, and D. Milward, “Low-cost, precision, self-alignment technique for coupling laser and photodiode arrays to polymer waveguide arrays on multilayer PCBs”, IEEE Trans. Advanced Packaging, 31, 502, (2008), http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4534823 .

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (13)

Fig. 1
Fig. 1

Fabrication process of W-shaped refractive index profile PPOW.

Fig. 2
Fig. 2

(a) W-shaped and (b) previously obtained GI-PPOW illuminated by a Halogen-Tungsten lump.

Fig. 3
Fig. 3

Near-field patterns of GI PPOW (a) when the core center and (b) cladding are launched and W-shaped PPOW (c) when the core center and (d) cladding are launched.

Fig. 4
Fig. 4

Propagation loss of SI, GI, and W-shaped PPOW.

Fig. 5
Fig. 5

The interference fringe patters (top) and its corresponding refractive index profile (bottom) of (a) GI (b) W-shaped profile with 3.66 wt. % BzMA PPOW.

Fig. 6
Fig. 6

Experiment setup for inter-channel crosstalk measurement.

Fig. 7
Fig. 7

Output intensity when one of the cores (second from the left) in waveguides is launched via (a) SMF probe (RML condition) and (b) MMF probe (near OML condition). The concentration of BzMA for W-shaped profile PPOW here is 10 wt. %.

Fig. 8
Fig. 8

(a) The measured refractive index profile of W-shaped profile PPOW with 10 wt. % BzMA in cladding. In the right side are the calculated ray trajectories with different incident angles. (b) The theoretical modeling of refractive index profile according to Eq. (1).

Fig. 9
Fig. 9

The launching condition for the simulation. We apply the same condition as the experimental setup in which the second core from the left side is launched by an MMF (50 μm in diameter).

Fig. 10
Fig. 10

Calculated NFP and propagation loss with corresponding output end (1 cm to 5 cm) for various refractive index of cladding under very lossy condition: (a) 1.492 (GI), 0.56 dB/cm (b) 1.495 (3.66 wt. % of BzMA), 0.58 dB/cm (c) 1.499 (10 wt. % of BzMA), 0.60 dB/cm (d) 1.502 (15 wt. % of BzMA), 0.60 dB/cm.

Fig. 11
Fig. 11

Calculated results by ray trace simulation: (a) Output intensity from the launched core. (b) Output intensity from the whole cladding. (c) Crosstalk value (XT) to the left-edge core. (d) Crosstalk value to the third core from the left edge.

Fig. 12
Fig. 12

Calculated NFP and propagation loss of W-shaped PPOWs with various refractive index of cladding compared to that of GI PPOW: (a) 1.492 (GI), 0.26 dB/cm (b) 1.495 (3.66 wt. % of BzMA), 0.26 dB/cm (c) 1.499 (10 wt. % of BzMA), 0.27 dB/cm (d) 1.502 (15 wt. % of BzMA), 0.26 dB/cm.

Fig. 13
Fig. 13

Calculated results by ray trace simulation (a) Output intensity from the launched core. (b) Output intensity from the whole cladding. (c) Crosstalk value (XT) to the left-edge core. (d) Crosstalk value to the third core from the left edge.

Tables (3)

Tables Icon

Table 1 Relationship Between Crosstalk Value and Refractive Index of the Cladding With Corresponding Concentration of BzMA

Tables Icon

Table 2 Crosstalk Value in 5-cm GI and W-Shaped PPOWs

Tables Icon

Table 3 Parameters for Calculation by Ray Tracing Method

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

{ n ( r ) = n 1 [ 1 2 Δ ( r / a ) g ] 1 / 2 ,         0 r a       n ( r ) = n 2 ,                   a < r ( a + w )     n ( r ) = n 3 ,                   ( a + w ) < r      
X T ( d B ) = 10  log I 1 I 0

Metrics