Abstract

We present the first systematic design approach for compact polarization-independent mode-size transformers based on tapered resonant vertical couplers with transfer efficiencies greater than 90%. Resonant coupling occurs at a critical taper width having equal TE and TM effective index. Being polarization-independent broadens the usefulness of vertical coupler as a building block for minimizing insertion loss in photonic integrated circuits.

© 2004 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |

  1. B. Mersali, H. J. Bruckner, M. Feulillade, S. Sainson, A. Ougazzaden, and A. Carenco, �??Theoretical and experimental studies of a spot-size transformer with integrated waveguides for polarization insensitive optical amplifiers,�?? J. Lightwave Technol. 13, 1865-1872 (1995).
    [CrossRef]
  2. I. Moerman, P. P. van Daele, P. M. Demeester, �??A review on the fabrication technologies for the monolithic integration of tapers with optoelectronic devices�??, IEEE J. Sel. Top. Quantum Electron. 3, 1308 (1997).
    [CrossRef]
  3. R. Y. Fang, D. Bertone, M. Meliga, I. Montrosset, G. Oliveti, R. Paoletti, �??Low-Cost 1.55-μm InGaAsP�??InP Spot Size Converted (SSC) Laser with Conventional Active Layers,�?? IEEE Photon. Technol. Lett. 9, 1084-1086 (1997).
    [CrossRef]
  4. P. Sewell, T. M. Benson, and P. C. Kendall, "Rib waveguide spot-size transformers: Modal properties," J. Lightwave Technol. 17, 848 (1999).
    [CrossRef]
  5. V. Vusirikala, S. S. Saini, R. E. Bartolo, S. Agarwala, R. D. Whaley, F. G. Johnson, D. R. Stone, M. Dagenais, �??1.55-μm InGaAsP�??InP Laser Arrays with Integrated-Mode Expanders Fabricated Using a Single Epitaxial Growth,�?? IEEE J. Sel. Top. Quantum Electron. 3, 1332-1343 (1997).
    [CrossRef]
  6. O. Mitomi, N. Yoshimoto, K. Magari, T. Ito, Y. Kawaguchi, Y. Suzaki, Y. Tohmori, and K. Kasaya, "Analyzing the polarization dependence in optical spot-size converter by using a semi-vectorial finite-element beam propagation method," J. Lightwave Technol. 17, 1255-1262 (1999).
    [CrossRef]
  7. M. K. Chin, "Polarization dependence in waveguide-coupled micro-resonators," Opt. Express 11, 1724-1730 (2003), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-15-1724">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-15-1724</a>.
    [CrossRef] [PubMed]
  8. BeamPROPTM Version 5.0 Beta (RSoft Inc, U.S., 2001), Chap. 1.
  9. Coldren, L. A., Corzine, S, W., Diode lasers and photonic integrated circuits (John Wiley & Sons, Inc, NY, U.S., 1995), Chap. 6.

IEEE J. Sel. Top. Quantum Electron. (2)

I. Moerman, P. P. van Daele, P. M. Demeester, �??A review on the fabrication technologies for the monolithic integration of tapers with optoelectronic devices�??, IEEE J. Sel. Top. Quantum Electron. 3, 1308 (1997).
[CrossRef]

V. Vusirikala, S. S. Saini, R. E. Bartolo, S. Agarwala, R. D. Whaley, F. G. Johnson, D. R. Stone, M. Dagenais, �??1.55-μm InGaAsP�??InP Laser Arrays with Integrated-Mode Expanders Fabricated Using a Single Epitaxial Growth,�?? IEEE J. Sel. Top. Quantum Electron. 3, 1332-1343 (1997).
[CrossRef]

IEEE Photon. Technol. Lett. (1)

R. Y. Fang, D. Bertone, M. Meliga, I. Montrosset, G. Oliveti, R. Paoletti, �??Low-Cost 1.55-μm InGaAsP�??InP Spot Size Converted (SSC) Laser with Conventional Active Layers,�?? IEEE Photon. Technol. Lett. 9, 1084-1086 (1997).
[CrossRef]

J. Lightwave Technol. (3)

Opt. Express (1)

Other (2)

BeamPROPTM Version 5.0 Beta (RSoft Inc, U.S., 2001), Chap. 1.

Coldren, L. A., Corzine, S, W., Diode lasers and photonic integrated circuits (John Wiley & Sons, Inc, NY, U.S., 1995), Chap. 6.

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 (5)

Fig. 1.
Fig. 1.

Schematic of an active device with a vertical coupler at each end that acts as mode size transformer.

Fig. 2.
Fig. 2.

Effective indexes of the coupled waveguide for TE and TM modes at various taper widths

Fig. 3.
Fig. 3.

(a) Critical widths, and (b) effective indexes for the different combinations of core thickness and refractive index for the upper waveguide. The color bands represent the different ranges of critical width or effective index

Fig. 4.
Fig. 4.

Change of transfer efficiency with (a) initial width with final width set at 1.35 µm, and (b) final width with initial width set at 1.05 µm

Fig. 5.
Fig. 5.

(a) Contour plots along Y-Z axis for TE and TM propagation, and (b) the transfer efficiency of the polarization independent vertical coupler as a function of propagation distance. The transfer region begins at z=50 µm.

Equations (3)

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

a 1 ( z ) = [ a 1 ( 0 ) { cos ( s z ) + j δ s sin ( s z ) } j δ 12 s a 2 ( 0 ) sin ( s z ) ] e j β ¯ z
a 2 ( z ) = [ j κ 21 s a 1 ( o ) sin ( s z ) + a 2 ( 0 ) { cos ( s z ) j δ s sin ( s z ) } ] e j β ¯ z
s = δ 2 + κ 2 , δ = β 1 β 2 2 , κ = κ 12 κ 21 , β ¯ = β 1 + β 2 2

Metrics