Efficient coupling of light from an optical fiber to silicon waveguides is a challenging task in integrated photonics. Couplers based on adiabatic mode evolution have the advantages of high bandwidth and low loss but are often accompanied by longer device lengths. In this paper, we introduce the concept of adiabaticity map and optimize the coupling between an optical fiber and Si waveguides by selecting routes on the map that minimize unwanted mode coupling. The map clearly indicates areas in mode evolution where supermode coupling is large and identifies optimal routes for efficient mode evolution. Optimized interaction length and widths are obtained from the adiabaticity map. We obtain highly efficient coupling (96%) with large bandwidth (1-dB bandwidth 280 nm) and misalignment tolerance (⪆90 nm lateral misalignment range for 1-dB excess losses) for the TE polarization.
Optical waveguide devices based on adiabatic mode evolution have large bandwidth and fabrication tolerances, but they have longer device lengths in general. We define a suitable adiabaticity parameter for optical waveguides and derive the formulae for engineering the adiabaticity along the waveguide. The fast quasiadiabatic dynamics (FAQUAD) protocol can then be applied to redistribute adiabaticity over the length of the device, speeding up mode evolution in adiabatic waveguide devices. By homogeneously distributing the adiabaticity along the length of the devices, shortcuts to adiabaticity are found for adiabatic waveguide devices, resulting in significant length reductions from the conventional designs. Devices on silicon, including mode (de)multiplexers, polarization splitter-rotators and 3 dB couplers using the FAQUAD approach are discussed. The FAQUAD approach leads to devices that are compact, broadband, and have good fabrication tolerances.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.