Microdisk resonators for difference frequency generation in THz range

We theoretically investigated and designed a tunable, compact THz source in 1-10 THz range based on a nonlinear optical microdisk resonator. The lack of tunable THz source operating at room temperature is still one of the major impediments for the applications of THz radiation. The proposed device on an insulated borosilicate glass substrate consists of a nonlinear optical disk resonator on top of another disk capable of sustaining THz modes. A pair of Si optical waveguides is coupled to the nonlinear microdisk in order to carry the two input optical waves. Another pair of Si THz waveguides is placed beneath the input optical waveguides to couple out the generated THz radiation from the disk to receiver antenna. Both optical and THz disks are engineered optimally with necessary effective mode indices in order to satisfy the phase matching condition. We present the simulation results of our proposed device using a commercial finite element simulation tool. A distinguished THz peak coincident exactly with the theoretical calculations involving DFG is observed in frequency spectrum of electric field in the microdisk resonator. Our device has the potential to enable tunable, compact THz emitters and on-chip integrated spectrometers.