Periodic Reporting for period 1 - SiComb (CMOS compatible and ultra broadband on-chip SiC frequency comb)
Période du rapport: 2020-10-01 au 2022-03-31
Optical frequency comb has been a far-reaching new invention since the birth of the first optical laser in 1960. Among them microcomb has attracted extensive attention and effort benefitting the advances of the different materials platforms, nonlinear optics and nanofabrication. A microcomb is compact in micrometer size and could be easily integrated and manipulated for a wide range of applications such as spectroscopy, optical communication, metrology, optical atomic clocks, bio/chemical sensing, distance ranging, searching for exoplanets etc. Compared to the existing materials platforms which have demonstrated frequency combs (Si, GaP, Si3N4, Hedex, AlN, Diamond, AlGaAs, and LiNbO3), SiC shows huge potential to generate compact, high-efficiency frequency comb working at telecommunication wavelength range because of its exceptional and unique optical properties. Therefore SiComb project aims to demonstrate the first ever CMOS compatible and ultra- broadband on-chip SiC frequency comb. The overall objective of SiComb is to develop a new material platform, i.e. SiC for photonic integrated circuits (PIC).
In alignment with the objective of SiComb project, three technical work packages have been organized: WP1: silicon carbide on insulator (SiCOI) stacks formation; WP2: SiC nanophotonics devices fabrication and characterization and WP3: SiC optical devices’ system application. These three workpackages focuses on material, device and system respectively, with huge interactions among the work packages at the same time. The multidisciplinary nature of SiComb projects has posed challenges for partners with different background to understand each other deeply. One big achievement is that during the past 18 months
a united consortium is formed after large amounts of meetings and webinars. For WP1, both amorphous SiCOI stacks and 3C SiCOI stacks have been achieved. The amorphous SiCOI stacks are deposited by both plasma enhanced chemical vapour deposition (PECVD) and physical vapour deposition (PVD), and they are device fabrication ready. For WP2, a standard mask layout and a stable processing flow to evaluate the materials received from WP1 have been established. So far PECVD deposited amorphous SiCOI stacks show the lowest material loss: 5~6dB/cm measured by a retrofitted prism coupler setup. The waveguide propagation loss is about 7~8 dB/cm, derived from the resonance of a microring resonator, which indicated the fabrication introduced extra loss is already as low as about 2dB/cm. Thermal-optical coefficient of amorphous SiCOI was studied and quantified, and a prototype for temperature control is fabricated. For WP3, references system design and preliminary components specification are investigated.
a united consortium is formed after large amounts of meetings and webinars. For WP1, both amorphous SiCOI stacks and 3C SiCOI stacks have been achieved. The amorphous SiCOI stacks are deposited by both plasma enhanced chemical vapour deposition (PECVD) and physical vapour deposition (PVD), and they are device fabrication ready. For WP2, a standard mask layout and a stable processing flow to evaluate the materials received from WP1 have been established. So far PECVD deposited amorphous SiCOI stacks show the lowest material loss: 5~6dB/cm measured by a retrofitted prism coupler setup. The waveguide propagation loss is about 7~8 dB/cm, derived from the resonance of a microring resonator, which indicated the fabrication introduced extra loss is already as low as about 2dB/cm. Thermal-optical coefficient of amorphous SiCOI was studied and quantified, and a prototype for temperature control is fabricated. For WP3, references system design and preliminary components specification are investigated.
Applying SiC for optics is a novel field. A lot of research we are doing in the SiComb project is pioneering. For example, trying different new low temperature SiC deposition methods for energy saving meets the sustainable development goal. If any of the methods works, i,e, materials having lower loss than 1dB/cm at the end of the project, it will contribute dramatically to reduce the CO2 emission.