Solid-State Nonlinear Optical Switch with the Widest Switching Temperature Range Owing to Its Continuously Tunable T_c

Abstract

Interest on the nonlinear optical (NLO) switches that turn on/off the second-harmonic generation (SHG) triggered by the external stimulus (such as heat) have continuously grown, especially on the solid-state NLO switches showing superior stability, reversibility, and reproducibility. Herein, we discover (NH 4 ) 2 PO 3 F, as an entirely new solid-state NLO switch showing outstanding switch contrast and reversibility as well as strong SHG intensity (1.1 × KH 2 PO 4 (KDP)) and high laser-induced damage threshold (2.0 × KDP), undergoes a unique first-order phase transition that originates from a reversible hydrogen-bond rearrangement and needs to overcome an energy barrier. Accordingly, we put forward a strategy to continuously modify such an energy barrier by reducing the number of hydrogen bonds per unit cell via an isoelectronic replacement of NH 4 + by K + with a similar size yet incapability of providing any hydrogen bond. Consequently, K x (NH 4 ) 2−x PO 3 F (x = 0−0.3) exhibiting excellent switching performance are obtained. Remarkably, K x (NH 4 ) 2−x PO 3 F not only realizes a continuously tunable T c spanning from 270 to 150 K, representing the widest NLO switching temperature range ever known but also indicates the first solid-state NLO switch example with continuous T c . Intrinsically, such a T c decline depends on the weakening degree of the hydrogen-bonding interactions in the unit cell. These new insights will shed useful light on the future material design and open new application possibilities.

Two molybdenyl carbonates with different dimensional structures exhibiting huge differences in band gaps

“…Nonlinear optical (NLO) materials that could expand the laser frequency range through second harmonic generation (SHG) have been widely applied in the laser science and technology fields, such as materials processing, photoemission, semiconductor lithography, and large density storage. [1][2][3][4][5][6][7][8] Highquality NLO materials should satisfy the following standards: large SHG response, wide transmission band, appropriate birefringence, good physical and chemical stability, and facile growth of crystals. [9][10][11][12][13] Most importantly, it is essential that an NLO crystal should be noncentrosymmetric (NCS) without a center of symmetry.…”

A Nonlinear Optical Switchable Sulfate of Ultrawide Bandgap

“…Nonlinear optical (NLO) switchable materials, in which NLO responses are reversibly converted among diverse stable states under external stimulation, have attracted considerable interest owing to their prospective application in optoelectronic devices, such as switches, sensors, data storage, information processing of smart devices, and optical communication. [1][2][3][4][5] Over the past decades, researchers have devoted great effort to studying NLO switchable materials and found a number of NLO switchable materials in the liquid phase. 6,7 Meanwhile, a variety of efficient strategies have been put forward to explore solid-state crystalline NLO switchable materials, such as cation exchange, conformational reorganization, and "push-pull" molecules via photochromism.…”

Polarized Laser Switching with Giant Contrast in MOF‐Based Mixed‐Matrix Membrane

“…These switching processes possibly suffer from serious service temperature constrains (normally above/below room temperature), undiversified control methods, and limited on/off contrasts. [ 8 , 9 , 10 , 11 ] By comparison, NLO materials with up‐conversion lasing performance might be much more advantageous, such as easy room temperature operations, high signal‐to‐noise ratio, and convenient‐to‐distinguish readout. Especially, the control of polarized lasers with enhanced emission contrasts is conducive to the analysis of the information brought by scattered light in radar remote sensing and the modulation in high‐efficiency displays or coherent optical communication.…”