Title:
NOVEL FRAMEWORK FOR INTEGRATED NONLINEAR AND QUANTUM PHOTONIC SIGNAL PROCESSING
NOVEL FRAMEWORK FOR INTEGRATED NONLINEAR AND QUANTUM PHOTONIC SIGNAL PROCESSING
Author(s)
Eshaghian Dorche, Ali
Advisor(s)
Adibi, Ali
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Abstract
This thesis reports a novel integrated photonic framework for nonlinear and quantum
photonic signal processing, using platforms compatible with current standard fabrication
processes in microelectronics (also referred to as CMOS compatible where CMOS stands
for complementary metal-oxide semiconductors). This is achieved by the proper design of
integrated photonic devices enabling efficient interconnections between disaggregated
nodes in a network processing information. For this purpose, developing ultra-high-speed
interconnects along with efficient quantum interconnects are indispensable for semi-
classical and quantum regimes, respectively. Optical frequency combs (OFCs) on a chip in
form of Kerr-combs or microcombs have received considerable attention during the past
two decades, mainly for providing coherent states of light in a wide range of the spectrum.
Recently the quantum counterpart of microcombs received attention for generating photon-
pairs in a large number of resonant modes. Nonetheless, the mainstream in the realization
of OFCs using integrated photonic devices through conventional design approaches, make
them incompatible with the standard fabrication processes in semiconductor foundries. To
leverage the inherent advantages of this technology (i.e., Kerr-combs), it is crucial to design
devices compatible with the current standard fabrication processes in the semiconductor
foundries.
This thesis, for the first time, reports systematic design protocols to address the challenges
in conventional approaches for generating wideband Kerr-combs. Considering versatile
applications for the OFCs in a wide wavelength range from ultraviolet (UV) to near-
infrared (IR), and the importance of the quantum state of light, this thesis demonstrates designs for wideband Kerr-combs in related wavelengths for applications in optical atomic
clocks, precision measurements, biomedical imaging, and dense wavelength division
multiplexing (DWDM). For this purpose, the conventional design space for proper
dispersion engineering of optical microresonators, as the most important parameter in
wideband Kerr-comb generation, is addressed by introducing novel dispersion engineering
approaches based on coupled resonators with optimized coupling segments. This way, I
introduced the “coupling dispersion” as an additional degree of freedom to address the
shortcomings of the previous solutions for enabling optical microresonators with the
desired dispersion for wideband OFC generation. Further studies on the effect of detuning,
quasi-parity-time symmetry, and exceptional points are also studied. Structures with
wideband Kerr-combs for interaction with atoms/ions at near-UV (e.g., Ytterbium (Yb)
ion), near-visible (e.g., rubidium (Rb)) are studied. Wideband Kerr-combs in the near-IR
spectrum is also studied for their importance in optical communication through DWDM.
Generating entangled-photon states at the optical and microwave (MW) spectrum, as the
most important element in implementing quantum protocols toward a scalable quantum
network, is also demonstrated in this thesis. The former leveraged the designs for wideband
Kerr-combs providing appropriate dispersion. The entangled states at the MW regime are
of particular importance as the energy gap in superconductors (SC) and the energy splitting
of ground states in atoms/ions are within this range. Therefore, entangling these qubits with
improved connectedness between the qubits is of practical importance for scalable and
efficient quantum processors. In this thesis, I devise a new protocol for generating multi-
partite high-dimensional entangled states at MW and terahertz (THz) spectrum with a high
degree of entanglement persistency by introducing the soliton-induced dynamical Casimir effect (DCE) in a high-quality-factor (high-Q) MW resonator coupled to an optical
microresonator supporting optical solitons.
To establish an efficient interface between the flying qubits (photons) and the stationary
ones (atoms/ions), high-Q optical microresonators are essential. The high-Q resonator
enhances the light-matter interaction, enabling coherent interaction between the qubits.
Thus, a specific chapter is devoted to my efforts on the design, fabrication, and
characterization of required integrated photonic building blocks for efficient atom-photon
interactions. Ultra-high-Q optical microresonators are demonstrated at the optical
transition of the 87 Rb atom in the near-visible spectrum. Designs for improving optical
gratings are also done to improve the signal-to-noise ratios (for both Rb and calcium (Ca)
atoms). And finally, a path toward increasing the coupling between the thermal atoms and
optical microresonators for cavity quantum electrodynamics (cQED) is proposed and
demonstrated.
Finally, a hybrid platform based on integrating phase-change materials (PCMs) with the
integrated photonic platforms is discussed as a toolbox to suppress the fabrication
imperfections and trimming the integrated photonic devices, e.g., delay lines and
microresonators. This capability paves the way toward scalable low-power system
integrations.
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Date Issued
2021-05-03
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Resource Subtype
Dissertation