Over the last three decades, photonic crystals (PhCs) have attracted intense interests thanks to their broad potential applications in optics and photonics. Generally, these structures can be fabricated via either "top-down" lithographic or "bottom-up" self-assembly approaches. The self-assembly approaches have attracted particular attention due to their low cost, simple fabrication processes, relative convenience of scaling up, and the ease of creating complex structures with nanometer precision. The self-assembled colloidal crystals (CCs), which are good candidates for PhCs, have offered unprecedented opportunities for photonics, optics, optoelectronics, sensing, energy harvesting, environmental remediation, pigments, and many other applications. The creation of high-quality CCs and their mass fabrication over large areas are the critical limiting factors for real-world applications. This paper reviews the state-of-the-art techniques in the self-assembly of colloidal particles for the fabrication of large-area high-quality CCs and CCs with unique symmetries. The first part of this review summarizes the types of defects commonly encountered in the fabrication process and their effects on the optical properties of the resultant CCs. Next, the mechanisms of the formation of cracks/defects are discussed, and a range of versatile fabrication methods to create large-area crack/defect-free two-dimensional and three-dimensional CCs are described. Meanwhile, we also shed light on both the advantages and limitations of these advanced approaches developed to fabricate high-quality CCs. The self-assembly routes and achievements in the fabrication of CCs with the ability to open a complete photonic bandgap, such as cubic diamond and pyrochlore structure CCs, are discussed as well. Then emerging applications of large-area high-quality CCs and unique photonic structures enabled by the advanced self-assembly methods are illustrated. At the end of this review, we outlook the future approaches in the fabrication of perfect CCs and highlight their novel real-world applications.

From colloidal particles to photonic crystals: advances in self-assembly and their emerging applications

In this work, highly sensitive measurements of strain and temperature have been demonstrated using a fiber Bragg grating (FBG) sensor with significantly enhance sensitivity by all-optical signal processing. The sensitivity enhancement is achieved by degenerated Four Wave Mixing (FWM) for frequency chirp magnification (FCM), which can be used for magnifying the wavelength drift of the FBG sensor induced by strain and temperature change. Highly sensitive measurements of static strain and temperature have been experimentally demonstrated with strain sensitivity of 5.36 pm/με and temperature sensitivity of 54.09 pm/°C. The sensitivity has been enhanced by a factor of five based on a 4-order FWM in a highly nonlinear fiber (HNLF).

Sensitivity enhanced strain and temperature measurements based on FBG and frequency chirp magnification.

Comprehensive Review Tapered Optical Fiber Configurations for Sensing Application: Trend and Challenges.

The purpose of this study is to present the state of the art for fiber Bragg grating (FBG) acceleration sensing technologies from two aspects: the principle of the measurement dimension and the principle of the sensing configuration. Some commercial sensors have also been introduced and future work in this field has also been discussed. This paper could provide an important reference for the research community.,This review is to present the state of the art for FBG acceleration sensing technologies from two aspects: the principle of the measurement dimension (one-dimension and multi-dimension) and the principle of the sensing configuration (beam type, radial vibration type, axial vibration type and other composite structures).,The current research on developing FBG acceleration sensors is mainly focused on the sensing method, the construction and design of the elastic structure and the design of a new information detection method. This paper hypothesizes that in the future, the following research trends will be strengthened: common single-mode fiber grating of the low cost and high utilization rate; high sensitivity and strength special fiber grating; multi-core fiber grating for measuring single-parameter multi-dimensional information or multi-parameter information; demodulating equipment of low cost, small volume and high sampling frequency.,The principle of the measurement dimension and principle of the sensing configuration for FBG acceleration sensors have been introduced, which could provide an important reference for the research community.

Fiber Bragg grating based acceleration sensors: a review

Measurement of cable forces for automated monitoring of engineering structures using fiber optic sensors: A review

Fiber Bragg grating has embraced the area of fiber optics since the early days of its discovery, and most fiber optic sensor systems today make use of fiber Bragg grating technology Researchers have gained enormous attention in the field of fiber Bragg grating (FBG)-based sensing due to its inherent advantages, such as small size, fast response, distributed sensing, and immunity to the electromagnetic field Fiber Bragg grating technology is popularly used in measurements of various physical parameters, such as pressure, temperature, and strain for civil engineering, industrial engineering, military, maritime, and aerospace applications Nowadays, strong emphasis is given to structure health monitoring of various engineering and civil structures, which can be easily achieved with FBG-based sensors Depending on the type of grating, FBG can be uniform, long, chirped, tilted or phase shifted having periodic perturbation of refractive index inside core of the optical fiber Basic fundamentals of FBG and recent progress of fiber Bragg grating-based sensors used in various applications for temperature, pressure, liquid level, strain, and refractive index sensing have been reviewed A major problem of temperature cross sensitivity that occurs in FBG-based sensing requires temperature compensation technique that has also been discussed in this paper

https://www.spiedigitallibrary.org/journals/optical-engineering/volume-59/issue-6/060901/Fiber-Bragg-grating-sensors-for-monitoring-of-physical-parameters/10.1117/1.OE.59.6.060901.pdf

Fiber Bragg grating sensors for monitoring of physical parameters: a comprehensive review

Internet-based communication has become a major field, with a user base that is expanding day-by-day. The needs have overloaded the available bandwidth, and higher speed has become a mandatory requirement to satisfy the user demands and increased use of the internet. Therefore, there is a need for high-performance computers due to increasing dependence on computing technology. Optics is emerging as the best possible solution over electronics because it is capable of providing parallel data processing with fewer expenses and greater speed of more than 10,000 times faster than electronic computers. The main building block of optical computing is the all-optical logic gates, which are designed using different techniques. Different types of photonic crystal-based all-optical logic gates have been reviewed in detail by discussing the key characteristics and demonstrating the advantages over the previously available technologies (semiconductor optical amplifier and nonlinear waveguide) that are used to build all-optical logic gates.

All-optical photonic crystal logic gates for optical computing: an extensive review

Reducing the effect of scintillation in FSO system using coherent based homodyne detection

The ideal behavior of communication system requires a single frequency carrier In optical communication system, light is used as a carrier Practical laser source has a finite linewidth due to variations in the frequency of operation, hence, resulting in undesired phase perturbations in the signal whereas the ideal requirement is the delta function spectral shape at the carrier frequency The spectral shape gets broadened due to phase noise and is modeled as lorentzian shape Linewidth is a measure of stability of laser phase noise with time Coherent Optical Orthogonal frequency division multiplexing (CO-OFDM) along with the spectrally efficient Quadrature Amplitude Modulation (QAM) formats is emerging as one of the best solutions for future high speed fiber transmission systems Though the coherent, receivers have advantages in terms of sensitivity and selectivity, laser phase noise is the main limitation of such systems as the laser phase noise further causes common phase rotation of all the subcarriers per symbol and also results in inter carrier interference QAM formats are also susceptible to laser phase noise Phase noise in coherent systems is governed by laser linewidth Hence, it is very important to investigate the impact of laser linewidth in CO-OFDM systems This paper investigates the tolerable laser linewidths for different QAM formats in a 40 Gbps COOFDM system

/pdf/investigation-of-tolerable-laser-linewidth-for-different-42fhqdnc3v.pdf

Investigation of Tolerable Laser Linewidth for Different Modulation Formats in CO-OFDM Systems

In this study, an EA-substituted tin based perovskite solar cell with different hole transport material (PEDOT: PSS, Cu2O, CuI, CZTSe) have been investigated using device simulation software. The effects of absorber thickness, defect density, operating temperature, J–V characteristics, and Quantum efficiency have been considered to enhance the performance of the solar cell. To confirm the feasibility and validate the study, all the simulation results were compared with reported experiment data. According to the experimental work based on (FA0.9EA0.1)0.98EDA0.01SnI3 absorber layer, a maximum of 13% efficiency is achieved with PEDOT: PSS as the HTM. Whereas we have further optimized performance parameters and found the superior response (Voc = 0.8851 V, Jsc = 27.24 mA/cm2, FF = 77.91%, and PCE = 18.78%) while opted Cu2O as the hole transport material. This device structure FTO/Cu2O/(FA0.9EA0.1)0.98EDA0.01SnI3/IDL/PCBM/C60/Au provides the more efficient, reliable solution for replacing the lead-based perovskite solar cell. This study will aid researcher in a reasonable choice of materials and to predict the behavior of high performance solar cells before undergoing the fabrication process. 

/pdf/optimization-of-highly-efficient-and-eco-friendly-ea-3rq17egg.pdf

Divya Dhawan

Papers

Fiber Bragg grating sensors for monitoring of physical parameters: a comprehensive review

All-optical photonic crystal logic gates for optical computing: an extensive review

Reducing the effect of scintillation in FSO system using coherent based homodyne detection

Investigation of Tolerable Laser Linewidth for Different Modulation Formats in CO-OFDM Systems

Optimization of highly efficient and eco-friendly EA-substituted tin based perovskite solar cell with different hole transport material