Thin film wavelength converters for photonic integrated circuits

Monolithic ultra-high-Q lithium niobate microring resonator

“…The performances of these components have the potential to be dramatically improved as optical waveguides in bulk LN crystals are defined by ion-diffusion or proton-exchange methods which result in low index contrast and weak optical confinement. Integrated LN platform, featuring sub-wavelength scale light confinement and dense integration of optical and electrical components, has the potential to revolutionize optical communication and microwave photonics [1][2][3][4][5][6][7].The major road-block for practical applications of integrated LN photonics is the difficulty of fabricating devices that simultaneously achieve low optical propagation loss and high confinement. Recently developed thin-film LN-on-insulator technology makes this possible, and has resulted in the development of two complementary approaches to define nanoscale optical waveguides: hybrid and monolithic.…”

“…The hybrid approach integrates an easyto-etch material (e.g. silicon or silicon nitride) with LN thin films to guide light [2-4] with a relatively low propagation loss (0.3 dB/cm) [4]. However, the resulting optical modes only partially reside in the active material region (i.e.…”

“…The performances of these components have the potential to be dramatically improved as optical waveguides in bulk LN crystals are defined by ion-diffusion or proton-exchange methods which result in low index contrast and weak optical confinement. Integrated LN platform, featuring sub-wavelength scale light confinement and dense integration of optical and electrical components, has the potential to revolutionize optical communication and microwave photonics [1][2][3][4][5][6][7].…”

“…The ultralow loss, high optical confinement and tight bending radius combined with the ability to integrate microwave electrodes [7] will bring electro-optic [2,7] nonlinear optical [4] systems into a new design parameter space that has been inaccessible so far. This could enable a wide range of applications including those in ultralow loss quantum photonics [9] ,coherent microwave to optical conversion [10,11] and active topological photonics [12].…”

All-optically induced quasi phase matching in SiN waveguides for second harmonic generation enhancement

“…Unfortunately, χ (2) theoretically vanishes in the dipole approximation both for Si and SiN. On the one hand, attempts were reported to integrate well performing χ (2) materials, such as lithium niobate [6], on CMOS waveguides. On the other hand, photonic confinement leading to resonant structures with limited bandwidth [7], or symmetry breaking in strained Si waveguides [8] were employed to enhance the efficiency of second order processes.…”