Low-Dimensional Materials for Nonlinear Photonics and Optoelectronics Applications

Dear Colleagues,

[*] Background and history of this topic

Nonlinear optical phenomena have a rich history that dates back to the discovery of the second-harmonic generation effect in the 1960s. This discovery opened the door to the entire field of nonlinear optics. The development of nonlinear optical materials initially focused on crystals with specific symmetries that could exhibit these nonlinear effects. Over the years, the understanding of nonlinear optical theory has evolved significantly, from basic models to more sophisticated quantum-mechanical descriptions. This theoretical progress has driven the exploration of new nonlinear optical materials with enhanced properties.

The field has seen continuous expansion as new measurement techniques have been developed to accurately characterize nonlinear optical effects. These techniques have enabled a more detailed study of the behavior of nonlinear optical devices. From early, simple experiments to modern, complex setups, nonlinear optical measurements have played a crucial role in understanding and improving the performance of nonlinear optical systems. The history of nonlinear optics is also intertwined with the development of simulation methods, which have become essential tools for predicting and optimizing the behavior of nonlinear optical materials and devices.

[*] Aim and scope of the Special Issue

The aim of this Special Issue is to provide a comprehensive platform for the latest research in nonlinear optics. It will cover all aspects related to nonlinear optical materials, effects, devices, theory, simulation, and measurements. The scope includes, but is not limited to, the following:

In-depth investigations of new and existing nonlinear optical materials, their synthesis, and characterization. This involves understanding how their structure and composition influence nonlinear optical properties.

Explorations of novel nonlinear optical effects and their potential applications in various fields such as photonics, telecommunications, and imaging.

The development and improvement of nonlinear optical devices, including their design, fabrication, and performance optimization.

The advancement of nonlinear optical theory, from fundamental principles to more complex models that can accurately describe real-world systems.

Innovations in nonlinear optical simulation techniques to better predict the behavior of materials and devices under different conditions.

The refinement of nonlinear optical measurement methods to obtain more accurate and detailed data for analysis.

This Special Issue will bring together researchers from different disciplines to foster cross-fertilization of ideas and promote the overall growth of the nonlinear optical field.

[*] Cutting-edge research

Two-dimensional materials:

Two-dimensional materials, such as II-VI nanosheets, perovskite, MOF, COF and transition-metal dichalcogenides, remain hot research topics. In nonlinear photonics, their nonlinear optical responses can be precisely tuned through layer-number control and external-field modulation. For example, researchers have found that doping two-dimensional materials with an electric field can significantly change their second- and third-order nonlinear optical coefficients, providing a new way to design novel optoelectronic devices. In multiphoton imaging, based on the fluorescence characteristics and high nonlinear absorption of two-dimensional materials, high-resolution and low-toxicity biological imaging can be achieved. Their unique electronic structures make the multiphoton excitation process more efficient, facilitating in-depth studies of microscopic structures and biological processes within cells.

Quantum dot materials:

Quantum dot materials have attracted significant attention in the nonlinear optical field due to their size-dependent optical properties. By changing the size and composition of quantum dots, their absorption and emission characteristics can be adjusted over a wide spectral range. In optical limiting applications, quantum dots exhibit excellent performance. Their strong third-order nonlinear optical effect can effectively limit the transmission of high-intensity light, which can be used to protect optical sensors and human eyes from intense light damage. Meanwhile, in on-chip nonlinear optical devices, the integration of quantum dots with micro-and nano-structures enables efficient light modulation and signal-processing functions, promising to drive the development of optical communication and optical computing fields.

Hybrid materials:

Hybrid materials, combining the advantages of different materials, show unique nonlinear optical properties. For instance, organic–inorganic hybrid materials can integrate the designability of organic materials and the stability of inorganic materials. In the hybrid system of plasma-resonant materials and semiconductors, the plasma near-field enhancement effect can significantly improve the nonlinear optical response of semiconductor materials, making it possible to develop high-performance optical limiters and saturable absorbers. In addition, hybrid materials have great potential in constructing multifunctional nonlinear optical devices, enabling the simultaneous realization of multiple functions such as light modulation and light detection.

Plasma-resonant materials:

Plasma-resonant materials can manipulate light at the nanoscale through the local surface plasmon resonance (LSPR) effect. In nonlinear optics, these materials can greatly enhance the local electromagnetic field, thereby increasing the efficiency of nonlinear optical processes. In the design of metasurfaces based on plasma-resonant materials, precise control of light polarization, phase, and amplitude can be achieved. Using these properties, metasurfaces with special nonlinear optical functions, such as nonlinear holography and optical vortex generation, can be fabricated, bringing innovation to optical information processing and display technologies.

Metasurfaces:

Metasurfaces, as a two-dimensional artificial material, show great potential in the nonlinear optical field. Through careful design of their nanostructures, the regulation of various nonlinear optical effects can be achieved. For example, efficient second-harmonic generation and third-harmonic generation can be realized using metasurfaces, with efficiencies much higher than those of traditional materials. In the integration of on-chip nonlinear optical devices, metasurfaces can serve as key elements to miniaturize the optical path and enable multifunctionality. In addition, the combination of metasurfaces with other nonlinear optical materials, such as quantum dots or two-dimensional materials, can further expand their applications in optical communication, imaging, and sensing fields.

On-chip nonlinear optical devices:

On-chip nonlinear optical devices are the core part of optical integration. With the development of materials science and micro- and nano-fabrication technologies, the performance of these devices has been continuously improved. The use of new two-dimensional materials and quantum dot materials can reduce the power consumption of devices and increase the response speed. For example, a nonlinear modulator based on a silicon-based on-chip platform combined with two-dimensional materials has a smaller size and higher modulation efficiency. In addition, the integration degree of on-chip devices has been continuously increased, and multiple nonlinear optical functions can be realized on one chip, such as integrating optical limiting, optical switching, and wavelength conversion functions together to meet the requirements of complex optical communication systems and optical computing architectures.

Saturable absorbers:

Saturable absorbers play a crucial role in pulsed laser generation. New types of saturable absorber materials have emerged continuously, such as those based on two-dimensional materials and quantum dots. These materials have the advantages of a high saturable absorption coefficient and short recovery time. In the field of ultrafast lasers, two-dimensional-material-based saturable absorbers can achieve more stable laser output with shorter pulse widths. Through the optimization of material structure and preparation process, the performance of saturable absorbers can be further improved to meet the requirements of pulse laser characteristics in different application scenarios, such as optical time-division multiplexing systems in optical communication and femtosecond laser systems in biomedical imaging.

Optical limiting and multiphoton imaging:

Optical limiting technology and multiphoton imaging are inter-related and have co-developed in biomedical and optical protection fields. In biological tissue imaging, high-energy laser pulses are required, but excessive energy may damage the tissue. Optical limiting materials can protect biological tissues from such damage. Meanwhile, multiphoton imaging technology utilizes the nonlinear optical properties of materials to achieve deep-tissue imaging. New optical limiting materials, such as hybrid materials and plasma-resonant materials, can also be used for light intensity control in multiphoton imaging, improving imaging quality and safety. The co-development of the two provides more powerful tools for biomedical research and clinical applications.

[*] What kind of papers we are soliciting

Original research papers that present new findings on the synthesis, characterization, or theoretical understanding of nonlinear optical materials. This includes studies on the relationship between material structure and nonlinear optical properties.

Papers that report experimentally discovered or theoretically predicted novel nonlinear optical effects. Descriptions of the conditions under which these effects occur and their potential applications are highly encouraged.

Research on the design, fabrication, and performance evaluation of nonlinear optical devices. This can involve new device architectures, the improvement of existing device performance, or the integration of multiple functions within a single device.

Theoretical papers that contribute to the development of nonlinear optical theory. This includes new models, analytical solutions, or numerical methods for understanding nonlinear optical phenomena.

Studies on nonlinear optical simulation techniques, especially those that incorporate advanced computational methods or show improved accuracy in predicting material and device behavior.

Papers that describe new nonlinear optical measurement methods or significant improvements to existing ones. Case studies demonstrating the application of these measurements in real-world research are also welcome.

Review papers that provide a comprehensive overview of specific sub-fields within nonlinear optics, highlighting the current state-of-the-art and future directions.

Dr. Baohua Zhu
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• nonlinear optical materials
• nonlinear optical effects
• nonlinear optical devices
• nonlinear optical theory
• nonlinear optical simulation
• nonlinear optical measurements