Cavity-Enhanced Second-Order Nonlinear Photonic Logic Circuits

Abstract

A large obstacle for realizing quantum photonic logic is the weak optical nonlinearity of available materials, which results in large power consumption. In this paper, we present the theoretical design of all-optical logic with second order (χ (2) ) nonlinear bimodal cavities and their networks. Using semiclassical models derived from the Wigner quasi-probability distribution function, we analyze the power consumption and signal-to-noise ratio (SNR) of networks implementing an optical AND gate and an optical latch. Comparison between the second and third order (χ (3) ) optical logic reveals that while the χ (3) design outperforms the χ (2) design in terms of the SNR for the same input power, employing the χ (3) nonlinearity necessitates the use of cavities with ultra high quality factors (Q ∼ 10 6 ) to achieve gate power consumption comparable to that of the χ (2) design at significantly smaller quality factors (Q ∼ 10 4 ). Using realistic estimates of the χ (2) and χ (3) nonlinear susceptibilities of available materials, we show that at achievable quality factors (Q ∼ 10 4 ), the χ (2) design is an order of magnitude more energy efficient than the corresponding χ (3) design.

Fundamental Scaling Laws in Nanophotonics

“…Thus, all-optical nonlinear devices provide an interesting test-case to elucidate the efficacy of scaling. For our analysis, we consider both the 2 nd and 3 rd order material nonlinearity, as they exhibit differing scaling performance with quality factors as reported recently51. We note that, in our analysis, we assume the scaling primarily affects the cavity, and not the nonlinear materials.…”

Second harmonic generation spectroscopy on two-dimensional materials [Invited]

“…Essentially, silicon with centrosymmetry results in the lack of second order nonlinearity and hinders the application of second order nonlinear integrated photonics. But silicon-based photonic crystal cavity is proved to have both small mode volume (V m ) and high quality factor (Q), where light can be confined and exist for an extended period of time [54,55]. And the switching power for second order nonlinearity is proportional to V m Q 3 .…”

Optical Harmonic Generation in 2D Materials

“…[ 54,62 ] For example, despite graphene's centrosymmetric structure, it exhibits a strong THG response, whereas it has a weak SHG response. [ 63–66 ] Generally, the layer dependent THG response increases for layered materials such as, 2D TMDs, making it a valuable tool to identify layer number ( Table 2 ). [ 54 ] THG is sensitive to excitation wavelength and absorption (%), therefore, THG intensity is found to increase significantly when it overlaps with the B‐exciton in 1L MoS 2 .…”

“…Optical computing uses photonic logic, which is the use of photons in logic gates to implement logic functions (AND, OR, NOR, NAND, etc.). [ 66,335–339 ] OHG along with other nonlinear optical processes such as, difference‐frequency generation (DFG), sum‐frequency generation (SFG), etc. provide the main building blocks to implement photonic logic functions.…”

“…However, a large obstacle for realizing photonic logic is the weak optical nonlinearity properties of conventional materials resulting in large power consumption. [ 66 ] Here, we review the applications of nonlinear optics in some photonic devices such as, frequency modulators, tunable waveguides, and optical switches, etc.…”