Photonics is the branch of physical science that focuses on light, or photon, and its use for generating energy, detecting and transmitting information, amplifying optical signals, and more technical applications. Photonics is also the technology that generates and harnesses radiant energy whose quantum unit is the photon, such as light, and is applied to devices that run on light such as accurate lasers that are used for various delicate eye surgeries. Biophotonics, nanophotonics, and quantum optics are all fields that fall under the topic of photons.

Optical Physics is the branch of physics that studies the properties and behavior of electromagnetic radiation, including light and infrared radiation, and its interaction with matter, atoms, and molecules. Wave optics, ray optics, and nonlinear optics also fall under the optical physics. Studies in these branches include optical phenomenon, such as reflection, diffraction, refraction, and polarization.

Optical Metrology is the science of using light to define units of measurement. The measurements could focus on properties such as distance, time, and other data or even on the properties of light itself. Instruments used for measuring are also integrating optical sensors, sensors that convert light rays into electronic signals, for precise dimensions of structures.

Optoelectronics is the study and implementation of electronic and hardware devices that detect and utilize light. Optoelectronics also includes the research, design, and manufacturing of devices that convert photon signals into electrical signals and vice versa.There are different types of devices that have various abilities including detecting light, channeling light, emitting light, and being controlled by light.

Ophthalmology is the medical and surgical branch which deals with diagnosing and treating eye disorders such as blurred vision, cataracts, glaucoma, and more. Patients are treated by ophthalmologists, medical doctors who specialize in eye and vision care. Ophthalmologists are credited degrees in medicine and follow years of ophthalmology training to conduct eye exams, diagnose and treat diseases, and perform various eye surgeries.

Spectroscopy is an explorative tool used in fields such as physics, chemistry, and astronomy to study the composition and structure of matter through the interaction between the matter and electromagnetic radiation. Spectroscopy could also be applied to detect, identify and measure the data of atoms and molecules using spectra, a unique wavelength of electromagnetic radiation emitted by atoms and molecules.

Laser Science, or laser physics, is the study of lasers and its principles and applications. Laser, short for ‘light amplification by stimulated emission of radiation,’ is a device that generates an intense beam of light by stimulated emission of photons. Laser technology is used in several fields including science, medicine, military, and commercial. Some of the commonly used devices are laser printer, barcode scanners, and surgical lasers.

Electromagnetism is the branch of physics that studies the electromagnetic force, one of the four fundamental forces, that occurs between electrically charged particles. The electromagnetic force is made of electric and magnetic fields, and is responsible for electromagnetic radiation such as light. The electric forces are produced when electric charges are either at rest or in motion, and are responsible for most of the physical and chemical properties of atoms and molecules. Magnetic forces are produced by moving charges only and act solely on charges in motion.

Crystallography is the branch of experimental science that examines crystals, their properties, and inner structures to determine the arrangements of atoms using various methods including neutron diffraction, electron diffraction, and X-ray Crystallography. Crystallographers also construct detailed models of the atomic arrangements in solids by gathering information from analytical techniques such as microscopic imaging, spectroscopy, computer modeling, visualization, and X-ray fluorescence. These techniques provide necessary information of a material’s chemical makeup, crystal structure, properties, and any defects.

Biophysics is the branch of physics that applies physics, chemistry, and mathematical analysis to biological systems in order to understand the structure, dynamics, interactions, and overall functions of specific molecules, cells, tissues, and other biological systems. Biophysicists attempt to determine the properties of these biological molecules and how they assemble into a larger structure. Biomechanics is a sub-field for biophysics that studies the movements of biological organisms and the effects of external stimuli acted upon them. Biological engineering, or bioengineering, is the field where bioengineers apply biophysics and engineering to construct helpful and innovative products for use in many fields including medicine, renewable energy, and agriculture.

Atomic Physics is the branch of physics that studies the atoms as an isolated system of electrons and an atomic nucleus. Physicists, in this sub-field, primarily consider atoms in isolation and focus on the properties of atoms and the arrangement of electrons around the nucleus and the processes of how they change. Processes include ionization and excitation by photons or collisions with atomic particles.

Nuclear Physics is the branch of physics that studies the atomic nuclei, consisting of protons and neutrons at the center of an atom, and its interactions in several phases. Many sectors have benefited from the discoveries made in nuclear physics. Nuclear energy is used in various fields including medicine, agriculture, and electricity generation. With further research, nuclear physics can lead to more innovative technology.

Plasma Physics is the study of plasma, a state of matter consisting of charged particles. Plasma is an ionized gas, which is to say that plasma is created by heating a gas until the electrons detach from their parent atom or molecule. Some of the forms plasma takes are lightning, auroras, solar winds, and the low-pressure gas in fluorescent and neon lights. There are many modern technologies that implement plasma. A lot of industries use plasma for their technologies, and plasma is also used to make transmitters.

Physical Chemistry is the branch of chemistry that studies the physical structures of chemical compounds and matter, their interactions with other matter, and the bonds that hold their atoms together. Physical chemists use the principles of physics, mathematical analysis, and statistics such as thermodynamics, quantum chemistry, analytical dynamics, and statistical mechanics to study the behavior of atoms, molecules, and other chemical systems. There are many fields in physical chemistry including Chemical Kinetics, the study of the chemical processes, reaction mechanisms, and transition states. Photochemistry is another field which studies chemical reactions caused by visible light, ultraviolet or infrared radiation.

Condensed Matter Physics is the study of macroscopic and microscopic physical properties of matter. Condensed matter physicists, professionals in the physics field of condensed matter, try to understand the behavior of the phases solid and liquid by using physical laws. Most of the foundations for technological development is provided by condensed matter physics. For example, the invention of semiconductor chips and transistors have led to the common use of data storage, multimedia, and telecommunications. Condensed matter physics continues to uncover phenomena which lead to innovations in technology.

Aerodynamics is the study of interactions between air and other gaseous fluids on solid objects and moving bodies. A prominent application of aerodynamics is in the field of aeronautics, where scientists and engineers study, design, and manufacture aircrafts and other vehicles capable of flight. Aerodynamic designs are also applied for other vehicles such as automobiles and trains. The continued research in aerodynamics is also helping flight technology improve by enhancing analytical and design capabilities of aircrafts and enhancing ground and flight testing.

Astrophysics, also called the “space science,” is the branch of astronomy that incorporates the laws of physics and chemistry to observe and understand the nature of astronomical bodies such as the planets, moons, stars, asteroids, and more. Astrophysicists, professionals in the field of astrophysics, strive to understand the universe and our place in it by studying the birth, life, and death of these planets, stars, and galaxies. Some of the concepts of physics applied in astrophysics include classical mechanics, quantum mechanics, and particle physics. Cosmology is another branch of astronomy that studies the origin and evolution of the universe, but on a larger scale.

Atmospheric Physics is the branch of meteorology that applies physics to study the atmosphere of Earth and other planets and its weather systems using chemical models, radiative and other energy transfer processes in the atmosphere. Atmospheric physicists, people who specialize in the study of the atmosphere and its climates, model the weather by using cloud physics, spatial statistics, implementing elements of the Scattering Theory, and other methods related to mathematics and physics.

Geophysics is the branch of physics that applies physics to study the Earth, its shape, internal structure, composition, and its gravitational and magnetic fields. A sub-field of geophysics is geodynamics, where geophysicists apply physics and chemistry to understand how mantle convection shapes the Earth and leads to mountain building, earthquakes, volcanoes, and other geological phenomena. Mineral physics is also another sub-field that examines the material that compose the interior of the planet to understand and interpret the surface measurements of seismic waves, geomagnetic and electromagnetic fields.

Physical Oceanography is the branch of oceanography that studies the ocean and its physical conditions, properties, and processes within it. Oceanographers also focus on understanding the distribution of oceanic properties such as salinity, temperature, and chemical elements and gases caused by ocean circulations and fluid motion. There are primarily two approaches in studying the ocean and they are descriptive and dynamical oceanography. Descriptive physical oceanography is the research of the precise description of the ocean’s fluid motion using observations and complex numerical models. Dynamic physical oceanography is the research of the processes that govern the ocean's fluid motion using theoretical research, numerical models, and Geophysical Fluid Dynamics.

Extended Reality is the term that encapsulates the interactions of real and virtual worlds with the use of technologies such as Virtual, Augmented, and Mixed realities. Virtual Reality and Augmented Reality are simulated and interactive realities made possible by innovative technologies and small, lightweight optics that provide high quality experience. To differentiate, virtual reality (VR) is the simulated reality that uses software to produce images, sounds, and other sensations which allow users to shut out the physical world and immerse themselves in 3D worlds where they can move around and interact with virtual features and objects. Augmented reality is the interactive experience where objects in the real, physical world are enhanced by computer-generated information and other digital elements which allows users to experience the real world enriched by visual overlays, 3D models, and other digital media and information. Mixed reality (MR) is also a form of reality where the real and virtual worlds merge and human-machine interactions can be generated by computer and wearable technology. These emerging technologies are used in fields such as entertainment, education, medical, and military.