We propose an analytical, time domain model for microring and microdisk modulators which considers both their electrical and optical properties. Theory of the dynamics of microring/microdisk is discussed, and general solutions to the transfer matrix representation are presented. Both static and dynamic predictions from the model are compared to measurement results to demonstrate the accuracy of our model. Static predictions and measurements are presented for power and phase responses whereas dynamic predictions and measurements are presented for small-signal and large-signal operations. The model verifies that the chirping and modulation bandwidth of the modulators depend on the detuning state. Finally, the accuracy and scalability of several techniques employed in the model are discussed.
Next-generation high-capacity optical networks require flexible allocation of spectrum resources, for which low-cost optical filters with an ultra-wide bandwidth tunability beyond 100 GHz are desired. We demonstrate an integrated band-pass filter with the bandwidth continuously tuned across 670 GHz (117-788 GHz) which, to the best of our knowledge, is the widest tuning span ever demonstrated on a silicon chip. The filter also features simultaneous wavelength tuning and an unlimited free spectral range. We measured an out-of-band contrast of up to 55 dB, low in-band ripples of less than 0.3 dB, and in-band group delay variation of less than 8 ps. This result was achieved using cascaded Bragg-grating-assisted contra-directional couplers and micro-heaters on the 220 nm silicon-on-insulator platform with a very compact footprint of less than 7000 μm2. Another design with the bandwidth continuously tunable from 50 GHz to 1 THz is also presented.
Manipulating the coupling coefficient at subwavelength scales provides an additional degree of freedom in designing integrated Bragg gratings. We demonstrate asymmetric contradirectional couplers (contra-DCs) using sidewall-corrugated subwavelength grating (SWG) waveguides for broadband add-drop Bragg filters. We show that a SWG can effectively increase the overlap of coupled modes and thus the photonic band gap. The measured spectra show good agreement with the prediction of photonic band structure simulations. A record bandwidth of 4.07 THz (33.4 nm) has been achieved experimentally. A four-port Bragg resonating filter made of a phase-shifted Bragg grating SWG contra-DC is also demonstrated for narrow-band (near 100 GHz) filtering. All these devices are achieved on the 220-nm silicon-on-insulator platform with a compact length of less than 150 μm. These large stopband filters may find important applications such as band splitting, reconfigurable channel band switching, bandwidth-tunable filtering, and dispersion engineering.
We propose an analytical, time-domain model for microring modulators, which encompasses pn-junction and resonator dynamics. It shows excellent agreement with experiment for high frequency operation beyond 20 GHz. Pulse-amplitude modulation is predicted for up to 80 Gb/s.
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