All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

Abstract

In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits.

Unidirectional Optical Transmission in a Single-Layer Metallic Grating Consisting of Cambered Resonators

“…In the first type, the use of Magneto-optical [3], [4], liquid crystals [5], [6] or time-dependent [7] media inevitably comes up with an external either magnetic or electric field, which usually requires a precise and reliable control over the position, magnitude and direction of the field. Similarly, nonlinear media [8], [9] calls for high intensity. The second type is made of isotropic and linear materials and takes photonic crystals [10]- [12], gratings [13]- [15], and grating-photonic crystal [16], [17] as universal structures.…”

All-Optical Diode Action through Enhanced Nonlinear Response from Polymeric Photonic Crystal Microcavity

“…The realization of nonreciprocal or symmetry breaking in light transmission is an essential property for communication and information processing in an all-optical domain. Various efforts have been made for achieving asymmetrical light propagation in the past. − Most of these structures are complex and requires high electric/magnetic fields to achieve nonreciprocal transmission, questioning the feasibility of their on-chip integration. However, the nonreciprocity in light propagation in the nonlinear regime can be attained by cascading materials with dissimilar nonlinear absorption coefficients.…”

“…Like its electronic counterpart, an optical diode can block the propagation of light in one direction while permitting in the other direction. All-optical diodes have been realized earlier via non-reciprocal optical resonators, 1D photonic crystals 30,‑32 , electro-tunable liquid crystals, , coupled cavity QED system, micrometer-scale ring-resonators, the opto-acoustic effects, or the thermo-optic effect in silicon rings . Although these systems are conceptually novel, practical realizations of these structures requires complex fabrication techniques.…”

Coherent all-optical transistor based on frustrated total internal reflection

“…Using nonlinear effects to design all-optical switches is one of the primary methods in this field 6 – 12 . However, high-intensity requirement and difficulty in achieving a gain value more than unit have reduced interests in manufacturing all-optical transistors through this intensity-based mechanism.…”