Ultrafast electro-optical disk modulators for logic, communications, optical repeaters, and wavelength converters

Abstract

We propose a U-shaped pn junction in a silicon-on-insulator microdisk resonator to effectively double the junction-mode overlap in the state-of-the-art, vertical pn junction microdisk electro-optical (EO) modulators. The U-shaped pn junction promotes the maximum overlap between the junction depletion zone and the whispering gallery optical mode in the microdisk. By fully depleting the p region of the npn-sequenced U-junction, the capacitance is reduced below 3 fF, which significantly improves the speed and power performance. In this work, we implement the high-efficiency, depleted U-junction design to maximize the operating bandwidth of EO modulators, EO logic elements, EO 2 × 2 switches for wavelength-division cross-connects, 2 × 2 reconfigurable optical add-drop multiplexers, optical-to-electrical-to-optical (OEO) repeaterswith-gain, OEO wavelength converters, and 2 × 2 optical-optical logic gates. These devices all operate in the 7.6-to-50 GHz bandwidth range with ultralow energy consumption between 0.4 and 9.8 fJ/bit. By using CMOS-compatible materials and fabrication-feasible design dimensions, our proposed high-performance devices offer a promising potential in next-generation, high-volume electro-optical communications and computing circuits.

Reconfigurable optical logic in silicon platform

“…(3) The overall NRZ bit rate of the device is calculated to be 27.74 Gbps. The switching energy per bit, albeit higher than other reported designs 13,19,31 , is negligible compared to the energy on the order of micro-Jules, required by the electrothermal switching of the amorphous to crystalline states. For this reason, the FCD effect is unlikely to induce any phase change operation in the PCM.…”

“…In Fig. 5 b the transmission response of the disk resonator in the drop port is presented with applied biases of 0 V and − 3.4 V. Figure 5 c shows the change in refractive index of the vertical junction with reverse bias voltage between 0 V to 3.4 V. The total switching delay is defined as , where is the RC constant of the metallic contacts and is the photon lifetime 31 . The 3 dB bandwidth of the optical, electrical, and overall operation can be described as, where, and indicate the vacuum speed of light and resonance wavelength respectively.…”

Recent advances in integrated optical directed logic operations for high performance optical computing: a review

“…1, the computation of optical logic function can be performed by one or more switches. There are many kinds of optical switches that can be adopted to form the optical switching network on SOI platform, such as the Mach-Zehnder interferometer (MZI) [37][38][39][40], MRR [41][42][43][44], and micro-disk resonator (MDR) [45][46][47][48]. Among them, MZI is an interference device, while MRR and MDR are resonant devices.…”