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Spatially Shaping Waves to Penetrate Deep inside a Forbidden Gap
Ravitej Uppu1, Manashee Adhikary1, Cornelis A M Harteveld1
1Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Physical Review Letters
|May 14, 2021
Summary
Researchers can now send waves deeper into crystals by spatially shaping wave fronts. This technique enhances wave intensity up to 100x, extending penetration depth significantly beyond the Bragg length.
Area of Science:
- Condensed matter physics
- Photonics
- Wave physics
Background:
- Waves within a crystal's forbidden band are typically reflected due to Bragg interference.
- This reflection limits wave propagation to the Bragg length, a short distance within the crystal.
Purpose of the Study:
- To demonstrate a method for extending wave propagation depth into photonic crystals.
- To investigate the enhancement of internal wave energy density by controlling wave front shaping.
Main Methods:
- Utilizing two-dimensional silicon photonic crystals as an exemplary system.
- Spatially shaping wave fronts of incident light.
- Probing internal energy density via laterally scattered intensity.
Main Results:
- Achieved tunable enhancement of internal energy density at specific distances within the crystal.
- Observed intensity enhancements up to 100 times greater than with random wave fronts.
- Extended wave penetration depth up to 8 times the Bragg length, consistent with theoretical models.
Conclusions:
- Spatially shaping wave fronts offers a novel method to control mesoscopic wave transport.
- This technique significantly enhances wave penetration depth in photonic crystals.
- The findings are applicable to various types of waves, not just light.
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