25 research outputs found
Hybrid confinement of optical and mechanical modes in a bullseye optomechanical resonator
Optomechanical cavities have proven to be an exceptional tool to explore
fundamental and technological aspects of the interaction between mechanical and
optical waves. Such interactions strongly benefit from cavities with large
optomechanical coupling, high mechanical and optical quality factors, and
mechanical frequencies larger than the optical mode linewidth, the so called
resolved sideband limit. Here we demonstrate a novel optomechanical cavity
based on a disk with a radial mechanical bandgap. This design confines light
and mechanical waves through distinct physical mechanisms which allows for
independent control of the mechanical and optical properties. Our device design
is not limited by unique material properties and could be easily adapted to
allow large optomechanical coupling and high mechanical quality factors with
other promising materials. Finally, our demonstration is based on devices
fabricated on a commercial silicon photonics facility, demonstrating that our
approach can be easily scalable.Comment: 16 pages, 11 figure
Efficient anchor loss suppression in coupled near-field optomechanical resonators
FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQElastic dissipation through radiation towards the substrate is a major loss channel in micro-and nanomechanical resonators. Engineering the coupling of these resonators with optical cavities further complicates and constrains the design of low-loss optomechanical devices. In this work we rely on the coherent cancellation of mechanical radiation to demonstrate material and surface absorption limited silicon near-field optomechanical resonators oscillating at tens of MHz. The effectiveness of our dissipation suppression scheme is investigated at room and cryogenic temperatures. While at room temperature we can reach a maximum quality factor of 7.61k (fQ-product of the order of 10(11) Hz), at 22 K the quality factor increases to 37k, resulting in a fQ-product of 2 x 10(12) Hz.25253134731361FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ2008/57857-22012/17610-32012/17765-7153044/2013-
Dissipative Optomechanics in High-Frequency Nanomechanical Resonators
The coherent transduction of information between microwave and optical
domains is a fundamental building block for future quantum networks. A
promising way to bridge these widely different frequencies is using
high-frequency nanomechanical resonators interacting with low-loss optical
modes. State-of-the-art optomechanical devices rely on purely dispersive
interactions that are enhanced by a large photon population in the cavity.
Additionally, one could use dissipative optomechanics, where photons can be
scattered directly from a waveguide into a resonator hence increasing the
degree of control of the acousto-optic interplay. Hitherto, such dissipative
optomechanical interaction was only demonstrated at low mechanical frequencies,
precluding prominent applications such as the quantum state transfer between
photonic and phononic domains. Here, we show the first dissipative
optomechanical system operating in the sideband-resolved regime, where the
mechanical frequency is larger than the optical linewidth. Exploring this
unprecedented regime, we demonstrate the impact of dissipative optomechanical
coupling in reshaping both mechanical and optical spectra. Our figures
represent a two-order-of-magnitude leap in the mechanical frequency and a
tenfold increase in the dissipative optomechanical coupling rate compared to
previous works. Further advances could enable the individual addressing of
mechanical modes and help mitigate optical nonlinearities and absorption in
optomechanical devices.Comment: 10 pages, 4 figures, supplemental materia
Macaúba (Acrocomia aculeata) cake from biodiesel processing: a low-cost substrate to produce lipases from Moniliella spathulata R25L270 with potential application in the oleochemical industry
[Background]: Biodiesel industry wastes were evaluated as supplements for lipase production by Moniliella spathulata R25L270, which
is newly identified yeast with great lipolytic potential. Macaúba cake (MC), used for the first time in this work as inducer to produce lipases, and residual oil (RO) were mixed to maximise enzyme production. The lipase secreted was biochemically characterised.[Results]: The best ratio for the mixture (MC:RO) was 0.66:0.34 and the fitted values for lipase activity and total protein concentration were 0.98 U mL−1 and 0.356 mg mL−1, respectively. Maximum activity obtained (2.47 U mL−1) was achieved at 31.5°C and pH 6.7, and the enzyme was stable in this condition. A novel enzyme was purified and identified for the first time by mass spectrometry. The lipase efficiently hydrolysed different natural oils and exhibited selectivity in the production of eicosapentaenoic acid from fish oil.[Conclusion]: The use of MC and RO as a supplement to produce the new lipase from M. spathulata R25L270 may be one alternative for reducing lipase production costs and simultaneously adding value to biodiesel industry residues. The potential application of the lipase in the oleochemical industry was demonstrated by its pH and temperature stabilities and selective hydrolysis.This research was supported by Brazilian agencies: CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), INCT (Instituto Nacional de Ciência e Tecnologia) de Nanomateriais de Carbono, FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais), Rede Mineira de Toxinas com Ação Terapêutica and CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior).Peer reviewe
Silicon anisotropy in a bi-dimensional optomechanical cavity
In this work, we study the effects of mechanical anisotropy in a 2D
optomechanical crystal geometry. We fabricate and measure devices with
different orientations, showing the dependence of the mechanical spectrum and
the optomechanical coupling with the relative angle of the device to the
crystallography directions of silicon. Our results show that the device
orientation strongly affects its mechanical band structure, which makes the
devices more susceptible to fabrication imperfections. Finally, we show that
our device is compatible with cryogenic measurements reaching ground state
occupancy of 0.2 phonons at mK temperature.Comment: 5 pages 4 figure
Macaúba (Acrocomia aculeata) cake from biodiesel processing: a low-cost substrate to produce lipases from Moniliella spathulata R25L270 with potential application in the oleochemical industry
Macaúba (Acrocomia aculeata) cake from biodiesel processing: a low-cost substrate to produce lipases from Moniliella spathulata R25L270 with potential application in the oleochemical industry
[Background]: Biodiesel industry wastes were evaluated as supplements for lipase production by Moniliella spathulata R25L270, which
is newly identified yeast with great lipolytic potential. Macaúba cake (MC), used for the first time in this work as inducer to produce lipases, and residual oil (RO) were mixed to maximise enzyme production. The lipase secreted was biochemically characterised.[Results]: The best ratio for the mixture (MC:RO) was 0.66:0.34 and the fitted values for lipase activity and total protein concentration were 0.98 U mL−1 and 0.356 mg mL−1, respectively. Maximum activity obtained (2.47 U mL−1) was achieved at 31.5°C and pH 6.7, and the enzyme was stable in this condition. A novel enzyme was purified and identified for the first time by mass spectrometry. The lipase efficiently hydrolysed different natural oils and exhibited selectivity in the production of eicosapentaenoic acid from fish oil.[Conclusion]: The use of MC and RO as a supplement to produce the new lipase from M. spathulata R25L270 may be one alternative for reducing lipase production costs and simultaneously adding value to biodiesel industry residues. The potential application of the lipase in the oleochemical industry was demonstrated by its pH and temperature stabilities and selective hydrolysis.This research was supported by Brazilian agencies: CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), INCT (Instituto Nacional de Ciência e Tecnologia) de Nanomateriais de Carbono, FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais), Rede Mineira de Toxinas com Ação Terapêutica and CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior).Peer reviewe