Inverse Design of Traveling-Wave Phononic Devices
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Phononic devices could enable and improve a broad range of functions in the realm
of classical and quantum information processing. However, such devices are often
designed through analytic methods, combined with brute-force parameter sweeps,
which severely limits the designs that can be investigated. This work presents a
method for inverse-design of traveling-wave phononic devices, allowing a vastly larger
design space to be explored. At the heart of the method lies a fast calculation of
gradients using the adjoint method, whereby the gradient computation costs no
more than a single simulation. I show that this method is theoretically applicable to
phononic devices, and demonstrate that it works in simulation. As a proof-of-concept,
I attempt to design a phononic beamsplitter. The design process consists of two
steps: one with continuously varying materials which is non-physical, but easier to
optimize; and one with binary devices, accomplished through level-set methods. The
first step yields near perfect performance, achieving less than one percent reflection
and almost nothing scattering into other modes. The second step never reached
as good performance, though still a 46/46 split was obtained with around 8 % of
the power reflected. Though the resulting designs have some problems with small
features and sensitive performance, this method looks promising for use in the design
of future phononic devices.
Beskrivning
Ämne/nyckelord
phononic devices, quantum acoustics, inverse design, adjoint method, level-set, gradient descent, solid mechanics