High-speed and efficient silicon modulator based on forward-biased pin diodes

Abstract

Silicon modulators, which use the free-carrier-plasma effect, were studied, both analytically and experimentally. It was demonstrated that the loss-efficiency product, α · V π L, was a suitable figure of merit for silicon modulators that enabled their intrinsic properties to be compared. Subsequently, the dependence of V π L on frequency was expressed by using the electrical parameters of a phase shifter when the modulator was operated by assuming a simple driving configuration. A diode-based modulator operated in forward biased mode was expected from analyses to provide more efficient operation than that in reversed mode at high frequencies due to its large capacitance. We obtained an α · V π L of 9.5 dB·V at 12.5 GHz in experiments by using the fabricated phase shifter with pin diodes operated in forward biased mode. This α · V π L was comparable to the best modulators operated in depletion mode. The modulator exhibited a clear eye opening at 56 Gb/s operated by 2 V peak-to-peak signals that was achieved by incorporating such a phase shifter into a ring resonator.

Si photonic waveguides with broken symmetries: applications from modulators to quantum simulations

“…1,3,7,8) The Mach-Zehnder interferometer (MZI) is usually employed together with carrier injection structures such as a MOS capacitor, 42,96,97) a pn-junction diode, 98,99) and a pin-junction diode. 100) Alternatively, the electro-absorption (EA) effects such as quantum-confined Stark effect (QCSE) [101][102][103] and Franz-Keldysh effect (FKE) 104,105) are also used by integrating Ge quantum-well (QW) or epitaxially grown bulk. These EA modulators are expected to be promising for next generations.…”

“…Consequently, we needed to apply the relatively large peak-to-peak voltage V pp of 6V, and the energy per bit is still one order of magnitude larger than that of the state-of-the-art devices. 96,100,97) Nevertheless, it will be straightforward to scale the oxide thickness down to 2 nm even without introducing high-k gate stacks 2) in an industrial fabrication line.…”

Photonic configurable logic block for digital photonic integrated circuits

“…However, in a situation where only a single logical operation is required, the output in the non‐targeted port acts as the cross‐talk to the targeted port. The schematic representation of the MZI equipped with two P‐i‐N phase‐shifters in push–pull configuration [12, 13 ] is shown in Fig. 2.…”

Heterogeneously-Integrated Optical Phase Shifters for Next-Generation Modulators and Switches on a Silicon Photonics Platform: A Review

“…In the early stage, carrier-injection type modulators have been largely developed thanks to the large free-carrier effect and relatively easy fabrication process, but it suffers from limited device speed due to minority carrier lifetime. Although there have been reports on carrier-injection type high-speed modulators based on a pin junction, an additional function, e.g., pre-emphasis signals, for driver circuits, is required to supplement its limited electro-optical response [18]. The most common operation mechanisms for high-speed modulation are carrier depletion using a p-n junction [19][20][21][22][23][24] and carrier accumulation using a metal-oxide-semiconductor (MOS) capacitor [25][26][27], which are embedded in a Si waveguide, composing an interferometer or a resonator.…”