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Colorless grating couplers realized by interleaving dispersion engineered subwavelength structures.
Optics Letters
|October 10, 2013
Summary
Reducing subwavelength structure periods minimizes waveguide dispersion, enhancing grating coupler bandwidth. This design achieved a 3 dB bandwidth of ~117 nm, a significant improvement for optical devices.
Area of Science:
- Photonics and Optical Engineering
- Nanotechnology and Subwavelength Structures
Background:
- Waveguide dispersion in subwavelength structures limits device performance.
- Grating couplers are essential optical components requiring broad bandwidth.
Purpose of the Study:
- To investigate and reduce waveguide dispersion in subwavelength structures.
- To enhance the bandwidth of grating couplers using dispersion engineering.
Main Methods:
- Theoretical analysis of waveguide dispersion in relation to subwavelength structure periodicity.
- Design and fabrication of grating couplers with interleaved subwavelength structures.
- Experimental characterization of optical bandwidth and efficiency.
Main Results:
- Reducing subwavelength structure period was shown to decrease waveguide dispersion.
- Interleaved subwavelength structures in grating couplers achieved a 1 dB bandwidth of ~70 nm and a 3 dB bandwidth of ~117 nm.
- Peak efficiency of approximately -5.1 dB for transverse-electric polarized light at 1570 nm was demonstrated.
Conclusions:
- Dispersion engineering by reducing subwavelength structure periodicity effectively enhances grating coupler bandwidth.
- The proposed interleaved subwavelength structures offer a viable path to broadband photonic devices.
- Simulations confirmed an additional 12 nm increase in 1 dB bandwidth due to dispersion engineering.
