Microring

Recently Chao and Gua9 employed polymer microrings with sharp asymmetrical resonance for measuring glucose solutions. They found a detection limit of 24 mg/dl corresponding to a 3 x 10 5 index change. 

Little B.E., Chu S.T., Pan W., Kokubun Y., Microring resonator arrays for VLSI photonics, IEEE Phot. Techn. Letters 2000 12 323-325. 

Chao C-Y. and Guo L.J., Biochemical sensors based on polymer microrings with sharp asymmetrical resonance, Appl. Phys. Letters 2003 83 1527-1529. 

This chapter provides an overview of the basic principles and designs of such sensors. A chemical sensor to detect trace explosives and a broadband fiber optic electric-field sensor are presented as practical examples. The polymers used for the trace explosive sensor are unpoled and have chromophores randomly orientated in the polymer hosts. The electric field sensor uses a poled polymer with chromophores preferentially aligned through electrical poling, and the microring resonator is directly coupled to the core of optical fiber. 

Microring Resonator Theory and a Design Method 2.2.1 Basic Theory of Microring Resonators... 

Fig. 2.1 Basic microring resonator structures and their output characteristics, (a) One ring resona tor and one bus waveguide and (b) the corresponding resonance spectrum at the through port, (c) One ring resonator and two bus waveguides and (d) the corresponding resonance spectrum at the through port and drop port. Reprinted from Ref. 15 with permission. 2008 Institute of Electrical and Electronics Engineers...

Fig. 2.8 Transmission spectrum of a microring resonator with 1.1 pm coupling gap. Reprinted from Ref. 15 with permission. 2008 Institute of Electrical and Electronics Engineers...

For a microring resonator with a waveguide width of 5 pm and coupling gap of 200 nm, a resonance extinction ratio of 12 dB for TE polarization and 9 dB for TM polarization has been achieved, as shown in Fig. 2.10. The ring resonator had a race track shape with circular sections of 500 pm radius and straight coupling section of 100 pm in length. The width of the two exposed strips is about 50 pm. 

Chao, C. Y. Fung, W. Guo, L. J., Polymer microring resonators for biochemical sensing applications, IEEE J. Sel. Topics Quant. Electron. 2006, 12, 134 146... 

Sun, H. Dalton, L. Chen, A., Systematic design and simulation of polymer microring resonators with the combination of beam propagation method and matrix model, In Digest of the IEEE LEOS Summer Topical Meetings, 2007, 217 218... 

Paloczi, G. T. Huang, Y. Yariv, A. Mookherjea, S., Polymeric Mach Zehnder interferometer using serially coupled microring resonators, Opt. Express 2003, 11, 2666 2671... 

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