Magneto-Optic and Integrated Si3N4 Photonic Devices for C-band and Mid-IR Applications

Abstract

Active integrated silicon photonic devices have been essential for the advancement of data processing and communications for decades. Fabricating active photonic devices is costly and often involves complex processing methods. We demonstrate the ability to use an external 487 nm laser source to opto-thermally tune passive photonic devices. We explored various methods of tuning these devices using our short-visible wavelength source with tuning capabilities up to 24.4 pm/mW for a passive Si3N4 microring resonators with SiO2 cladding. By removing the cladding material using standard reactive ion etching techniques, we demonstrated an increase in thermal isolation that increased our tuning capabilities to 44.4 pm/mW. With these methods we successfully demonstrated the ability to tune the resonance of microresonators without integrating electrical contacts or by implementing a thermal stage. These methods provide potential alternatives to conventional thermal tuning techniques, especially for quality control in high volume manufacturing. The use of magneto-optics (MO) in Faraday rotators and other devices has been essential for the use and advancement of photonic devices and systems. The low Verdet constants and structural rigidity of current MO materials limit the potential for advancement in the field through on-chip MO device fabrication. To overcome this, we have synthesized high-Verdet MO polymer materials to integrate with silicon photonic devices; these materials were developed in the Pyun group in the Department of Chemistry/Biochemistry. By integrating these materials with high-Q Si3N4 resonators we have successfully shown a preliminary proof-of-concept for a functional magneto- optic modulator. This initial design integrated polymer-coated magnetic cobalt nanoparticles as the cladding material with a Si3N4 resonator with a Q factor of 2.2 million. By applying an external magnetic field of 10 mT to the device, we demonstrated extinction ratios up to 4.75 dB for the on- resonance wavelength position. These results show the potential for creating on-chip magneto- optic devices that can be used as modulators for telecommunications or as sensors for environmental or biomedical applications. By designing Si3N4 waveguides that can operate at both 1.55 μm and 4.6 μm we have demonstrated the possibility of fabricating dual-purpose photonic devices for sensing and communication systems. We have designed, simulated and experimentally measured a triple core Si3N4 waveguide that guides a supermode at 4.6 μm as well as single modes at 1.55 μm. The insertion losses for these waveguides are as low as -6.70 dB and -7.04 dB for 4.6 μm and 1.55 μm respectively. These results show that by creating multi-core waveguides we can successfully guide MWIR modes with low loss as compared to current waveguide designs. The ability to fabricate these devices using standard fabrications techniques demonstrates promise in creating dual-purpose photonic devices for multi-wavelength applications.