Lecture by Dr. Alfredo de Rossi, Thales Research and Technology

Title: Tailored confinement of optical and mechanical modes using biperiodic photonic crystals


The inherent complexity of semiconductor structures which can be fabricated through the modern patterning techniques has motivated strategies for achieving the optimal confinement of optical [1]and mechanical [2] modes, based on heavy optimization procedures. Yet, it has been shown that much simpler structures based on the superposition of two close periods generate an almost perfect effective confining potential with minimized radiation losses [3].

We have discovered that this concept also results into an effective harmonic potential for the photons, creating modes which map on the quantum harmonic oscillator. This allows the realisation of an almost ideal optical parametric oscillator with a minimal set of highly confined modes[4]. Moreover, we confirm that the confinement is robust to disorder and with minimal changes the design adapts to other photonic platform, leading to a record high Q factor in PhC cavities fully embedded in a Silica cladding an made using a standard CMOS process[5]Finally, we show that the concept also works for the simultaneous confinement of optical and mechanical modes, resulting into an original approach to cavity optomechanics.

1.Minkov, M., Savona, V. & Gerace, D. Photonic crystal slab cavity simultaneously optimized for
ultra-high Q/V and vertical radiation coupling. Applied Physics Letters 111, 131104 (2017).
2. Chan, J., Safavi-Naeini, A. H., Hill, J. T., Meenehan, S. & Painter, O. Optimized optomechanical
crystal cavity with acoustic radiation shield. Applied Physics Letters 101, 081115 (2012).
3. Alpeggiani, F., Andreani, L. C. & Gerace, D. Effective bichromatic potential for ultra-high Qfactor
photonic crystal slab cavities. Applied Physics Letters 107, 261110 (2015).
4 S. Combrié, G. Lehoucq, G. Moille, A. Martin, A. De Rossi, Comb of high‐Q Resonances in a
Compact Photonic Cavity, Laser & Photonics Reviews 2017, 11, 1700099.
5 Dodane, D., Bourderionnet, J., Combrié, S., & de Rossi, A. Fully embedded photonic crystal
cavity with Q= 0.6 million fabricated within a full-process CMOS multiproject wafer. Optics
express, 26(16), 20868-20877 (2018).


Mon 17 Sep 18
15:00 - 16:00


Lyngby Campus
Building 341, aud. 23