Journal of Lasers, Optics & Photonics

In the realm of medical imaging, one technology stands out for its remarkable ability to reveal the hidden intricacies of biological tissues optical Coherence Tomography Using laser light, OCT has revolutionized our understanding of both the micro and macroscopic structures within living organisms. In this article, we will delve into the fascinating world of OCT, exploring its principles, applications, and its potential to transform the way we diagnose and treat various medical conditions. To appreciate the workings of OCT, we must first understand the fundamental properties of light. Light is an electromagnetic wave characterized by its wavelength, frequency, and velocity. In the visible spectrum, different colors of light correspond to varying wavelengths, with red light having longer wavelengths and blue light having shorter wavelengths. Interference is a crucial concept in OCT. When two light waves of the same wavelength overlap, they can either amplify or cancel each other out, depending on whether they are in-phase or out-of-phase. Coherence, in this context, refers to the consistency of the phase relationship between these waves. OCT relies on the Michelson interferometer, a device that splits an incident beam of light into two paths and then recombines them.

The manipulation and control of light have been at the forefront of scientific and technological advancements for centuries. In recent years, a groundbreaking technology has emerged - metasurfaces. These nanoscale structures have revolutionized laser optics by enabling precise control over the properties of light, such as its phase, amplitude, and polarization. In this article, we will explore the fascinating world of metasurfaces, delving into their principles, design strategies, applications, and the transformative impact they have had on laser optics. Metasurfaces are twodimensional arrays of subwavelength optical elements that interact with light at the nanoscale. These optical elements are typically nanoantennas, nanoresonators, or other nanostructures designed to manipulate the properties of light. Metasurfaces work by controlling the phase, amplitude, and polarization of incident light through strong light-matter interactions at the nanoscale. They can be engineered to create specific optical effects, making them powerful tools for shaping light. Metasurfaces can be designed with phaseshifters, which introduce specific phase delays to incident light, and resonators, which enhance light-matter interactions. The precise arrangement and geometry of these elements dictate the behavior of the metasurface.

Optical tweezers have emerged as a revolutionary tool in the world of microscopy and biophysics. These devices use the power of precision lasers to manipulate microscopic objects, including individual cells, nanoparticles, and even single molecules. In this article, we explore the fascinating world of optical tweezers, delving into their underlying principles, the technology that makes them possible, and their wide-ranging applications. From biological research to nanotechnology, optical tweezers have transformed our ability to interact with the microscale world in ways previously unimaginable. Optical tweezers rely on the principles of optical trapping, where highly focused laser beams create a gradient of optical forces that can trap and manipulate tiny objects. The article will explain how these forces arise, including concepts like radiation pressure and gradient force. It will also discuss the importance of laser beam properties such as wavelength and polarization in optical trapping. Recent developments in laser technology and microscopy techniques have greatly improved the capabilities of optical tweezers. Advanced setups now incorporate multiple laser traps, feedback control systems, and real-time imaging to enhance precision and flexibility.

The world of lasers and photonics has undergone a remarkable transformation with the emergence of Photonic Crystal Fibers (PCFs). These innovative optical fibers have revolutionized the way we guide and manipulate light in laser systems, enabling unprecedented control over various optical parameters. In this article, we will explore the intriguing world of PCFs, delving into their structure, unique properties, applications, and the impact they have had on a wide range of industries. Traditional optical fibers have been instrumental in transmitting data and telecommunications signals over long distances with minimal loss. These fibers typically consist of a core and cladding that guide and contain light through total internal reflection. While traditional optical fibers are effective for many applications, there was a need for fibers that could provide greater control over light-matter interactions, enable broader bandwidths, and adapt to various laser systems. Photonic Crystal Fibers emerged as a solution to these challenges. Photonic Crystal Fibers are a type of microstructured optical fiber characterized by a periodic arrangement of airholes in the core and cladding regions. The size and arrangement of these airholes are precisely engineered to manipulate the behavior of light in ways that were previously unattainable. The guiding mechanism in PCFs relies on the photonic bandgap effect, which occurs due to the periodicity of airholes. This effect allows PCFs to guide light through a low-index core region, even when the refractive index of the core is less than that of the cladding.

In present scenario, there is an urgent need to develop technologies and devices for Defense and Security applications to not just maintain the sovereignty of international boarders but also to safeguard the countrymen from hostile terror forces within the homeland. In the present paper, results of detection studies for Improvised Explosive Devices (homemade explosive), Chemical Warfare Agents, (CWA) and drugs have been presented. Quantum Cascade Laser having wavelength in mid-IR region (wave number region ~ 900 to 1400 cm-1) has been utilized in the study as explosives and CWA have strong absorption in the region. The Quantum Cascade Laser has advantages of compact size and relatively smaller weight in comparison to other sources working in the same wavelength region. The detection limit of the setup has been measured. The detection technique presented here is immune to the interferences by sonic or other electromagnetic waves present in the surrounding atmosphere making the technology suitable for Defence, Security and forensic purposes.