High-speed and high-contrast two-channel all-optical modulator based on solution-processed CdSe/ZnS quantum dots

Abstract

Recently, all-optical modulators are potentially the most promising candidate to achieve high-bit rate modulation in high-speed all-optical communication technologies and signal processing. In this study, a two-channel all-optical modulator based on a solution-processed quantum dot structure is introduced for two sizes of quantum dots to operate at two wavelengths of MIR spectra (3 µm and 5 µm). To perform numerical and theoretical analysis and evaluate the optical behavior of the proposed all-optical modulator, the coupled rate and propagation equations have been solved by considering homogeneous and inhomogeneous broadening effects. The modulation depth at the 50 GHz frequency and 3 mW probe power is attained, about 94% for channel-1 with the wavelength of 559 nm at 300 Wcm−2 pump power density as well as approximately 83.5% for channel-2 with the wavelength of 619 nm at 500 Wcm−2 pump power density. The introduced two-channel all-optical modulator can operate simultaneously at two wavelengths during the modulation process in which information could be transmitted through both signals from the control light. This approach can present the practical device as a high-contrast and high-speed two-channel all-optical modulator with a high modulation depth in numerous applications such as thermal imaging in night vision cameras, wavelength de-multiplexing, signal processing, free-space communication.

Mixed Phase MoS2 Quantum Dots as Optical Limiters for Ultrafast Lasers

“…The diffraction efficiency and third-order optical susceptibility are also measured through the OPC technique. The intensity-dependent refractive index and strong nonlinear absorption response (RSA) of the dots along with the large surface to volume ratio and reduced size have potential applications in optical modulation, 69 optical limiting, 70 and multiphoton imaging. 71 2D materials such as MoS 2 that possess polymorphs, which are both metallic and semiconductors, offer challenges for RSAbased optical limiting applications.…”

Nondestructive All-Optical Readout through Photoswitching of Intramolecular Excimer Emission

“…Azobenzene derivatives are the most studied because of their large geometrical changes upon light irradiation, but they suffer from low thermal stability . We learned during the study of molecules that can be photoactived that the specifications of reversibility, fatigue-resistance, and nondestructive readout are crucial toward operating photoresponsive molecular systems, particularly in the fields of bioimaging or molecular data storage. − In addition, the choice of an optical output signal appears both beneficial and challenging. ,, Among the all-optical molecular systems reported to date for the photocontrol of linear or nonlinear optical output, a common design combines photochromic and fluorescent units, where the fluorescence emission is modulated by the photochromic reaction. Among the various photochromic compounds known to date, the dithienylethenes (DTE) are the most suitable for fluorescence photoswitching owing to their excellent thermal stability and fatigue resistance. ,− The “ON”/”OFF” readout process is usually based on the contrast between the observed fluorescence of the open form of the DTE system (DTEo) and the fluorescence quenching of the closed DTE compound (DTEc).…”