Selected work includes:
- “Propagation and imaging of mechanical waves in a highly-stressed single-mode phononic waveguide,” Physical Review Applied, vol. 11, no. 6, Jun. 2019. (pdf)
- “Light-Mediated Cascaded Locking Multiple Nano-Optomechanical Oscillators,” Physical Review Letters, vol. 118, p. 063605, 2017. (pdf)
- “Scalable high-precision tuning of photonic resonators by resonant cavity-enhanced photoelectrochemical etching,” Nature Communications, vol. 8, p. 14267, 2017. (pdf)
- “High-frequency nano-optomechanical disk resonators in liquids,” Nature Nanotechnology, vol. 10, pp. 810–816, 2015. (pdf)
- “Photoelastic coupling in gallium arsenide optomechanical disk resonators,” Optics Express, vol. 22, no. 12, pp. 14072–14086, 2014. (pdf)
- “High frequency GaAs nano-optomechanical disk resonator,” Physical Review Letters, vol. 105, no. 26, p. 263903, 2010. (pdf)
- “Optical instability and self-pulsing in silicon nitride whispering gallery resonators,” Optics Express, 20, 27, 29076, 2012 (pdf) – Skip to section
- “Ultrahigh Q-frequency product for optomechanical disk resonators with a mechanical shield,” Applied Physics Letters, 103, 24, 241112, 2013, doi: 10.1063/1.4846515. – Skip to section
- Improved Optomechanical Disk Resonator Sitting on a Pedestal Mechanical Shield,
New Journal of Physics 17, 023016 (2015).
In progress…
Optical instability and self-pulsing in silicon nitride whispering gallery resonators
a WGM resonator for three distinct pump laser configurations. MATLAB script used to generate the red self-pulsing traces can be downloaded below.
We report time domain observations of optical instability in high Q silicon nitride whispering gallery disk resonators. At low laser power the transmitted optical power through the disk looks chaotic. At higher power, the optical output settles into a stable self-pulsing regime with periodicity ranging from hundreds of milliseconds to hundreds of seconds, as shown in the video below. This phenomenon is explained by the interplay between a fast thermo-optic nonlinearity within the disk and a slow thermo-mechanic nonlinearity of the structure. A model for this interplay is developed which provides good agreement with experimental data (see figure to the right and MATLAB script below) and points out routes to control this instability.
Read more here:
- C. Baker et al., “Optical instability and self-pulsing in silicon nitride whispering gallery resonators,” Optics Express, 20, 27, 29076, 2012, doi: 10.1364/OE.20.029076
Ultrahigh Q-frequency product for optomechanical disk resonators with a mechanical shield
We report on optomechanical GaAs disk resonators with ultrahigh quality factor-frequency product Q × f. Disks standing on a simple pedestal exhibit GHz mechanical breathing modes attaining a Q × f of 1013 measured under vacuum at cryogenic temperature. Clamping losses are found to be the dominant source of dissipation. An improved disk resonator geometry integrating a shield within the pedestal is then proposed, and its working principles and performances are investigated by numerical simulations. For dimensions compatible with fabrication constraints, the clamping-loss-limited Q reaches 107–109 corresponding to Q × f equals 1016–1018. This shielded pedestal approach applies to any heterostructure presenting an acoustic mismatch.
Read more here:
- D. T. Nguyen et al., “Ultrahigh Q-frequency product for optomechanical disk resonators with a mechanical shield,” Applied Physics Letters, vol. 103, no. 24, p. 241112, Dec. 2013, doi: 10.1063/1.4846515.
Improved Optomechanical Disk Resonator Sitting on a Pedestal Mechanical Shield
We experimentally demonstrate the controlled enhancement of the mechanical quality factor Q of gallium arsenide disk optomechanical resonators. Disks vibrating at 1.3 GHz with a mechanical shield integrated in their pedestal show a Q improvement by a factor 10–16. The structure is modeled numerically and different modes of vibration are observed, which shed light on the Q enhancement mechanism. An optimized double-disk geometry is presented that promises Q above the million for a large parameter range.
Read more here:
- D. T. Nguyen, W. Hease, C. Baker, E. Gil-Santos, P. Senellart, A. Lemaître, S. Ducci, G. Leo, and I. Favero, Improved Optomechanical Disk Resonator Sitting on a Pedestal Mechanical Shield, New Journal of Physics 17, 023016 (2015).
High-frequency nano-optomechanical disk resonators in liquids
Nano- and micromechanical resonators are the subject of research that aims to develop ultrasensitive mass sensors for spectrometry, chemical analysis and biomedical diagnosis. Unfortunately, their merits generally diminish in liquids because of an increased dissipation. The development of faster and lighter miniaturized devices would enable improved performances, provided the dissipation was controlled and novel techniques were available to drive and readout their minute displacement. Here we report a nano-optomechanical approach to this problem using miniature semiconductor disks. These devices combine a mechanical motion at high frequencies (gigahertz and above) with an ultralow mass (picograms) and a moderate dissipation in liquids. We show that high-sensitivity optical measurements allow their Brownian vibrations to be resolved directly, even in the most-dissipative liquids. We investigate their interaction with liquids of arbitrary properties, and analyse measurements in light of new models. Nano-optomechanical disks emerge as probes of rheological information of unprecedented sensitivity and speed, which opens up applications in sensing and fundamental science.
Read more here:
- “High-frequency nano-optomechanical disk resonators in liquids,” Nat Nano, 10, 9, 810, 2015
Origin of optical losses in gallium arsenide disk whispering gallery resonators
Read more here:
- D. Parrain et al., “Origin of optical losses in gallium arsenide disk whispering gallery resonators,” Optics Express, vol. 23, no. 15, p. 19656, Jul. 2015, doi: 10.1364/OE.23.019656.
Christopher G. Baker 