Careers in Optics

Career Opportunities in Optics

Optics is the science of the generation, propagation, reception, and display of electromagnetic radiation and its interaction with matter over a wide range of wavelengths from microwaves, infrared, visible, and ultraviolet up to X-rays and γ-rays, with an emphasis on infrared to ultraviolet wavelengths.

Research Directions in Optics

The research directions of the program are: quantum optics and quantum information, optoelectronics science and technology, optical information processing and computational design, and intense lasers and laser biology.

Cultivation Objectives of Optics

The program cultivates students with solid theoretical foundation in optics and basic experimental skills, with strong innovative ability; understanding of the current status of development of this field and research dynamics, familiar with the international frontiers of optics development; capable of engaging in scientific research, teaching, or undertaking specialized technical work, with strong comprehensive ability, language expression and writing ability.

Optics career direction

In addition to a certain percentage of graduates of this specialty to continue to graduate students, but also to higher education engaged in related teaching and research, or in the photovoltaic enterprises engaged in research and development, engineering and sales and other work.

History of Optics

Optics is a discipline with a long history, dating back more than 2000 years. The study of light by human beings was initially an attempt to answer questions such as "how can people see the objects around them". The world's earliest knowledge of optics was recorded in the Chinese book "Mojing" around 400 BC. It contains eight entries on optics, describing the definition and creation of shadow, the linear propagation of light, and pinhole imaging, and discusses in rigorous terms the relationship between object and image in plane, concave, and convex spherical mirrors (see History of Physics in China).

In the more than 2,000 years of history since the Mojing, after the invention of the convex lens by the Arab Ibn al-Haytham in the 11th century, and the simultaneous invention of the microscope, independently of each other, by H. Jensen and H. Lipsey between 1590 and the beginning of the 17th century, the observation of the reflection and refraction of light was not attributed to W. Snell and R. Descartes until the first half of the 17th century. the laws of reflection and refraction of light customarily used today.

In 1665 Newton conducted experiments with sunlight, which was able to break it down into simple components, forming a light distribution with colors arranged in a certain order - the spectrum. It brought people into contact with the objective and quantitative characteristics of light for the first time, and the spatial separation of each monochromatic light was determined by the nature of light. Newton also found a large radius of curvature of the convex lens on the optical flat glass plate, when irradiated with white light, the lens and glass plate contact with a group of colored concentric rings; when irradiated with a monochromatic light, a group of dark and light concentric rings, later called this phenomenon Newton's ring. With this phenomenon, the thickness of the air gap in the first dark ring can be used to quantitatively characterize the corresponding monochromatic light.

Newton in the discovery of these important phenomena at the same time, according to the linear propagation of light, that light is a kind of particle flow, particles from the light source to fly out in a uniform medium to comply with the laws of mechanics for the same speed straight line motion, and with this view of the phenomenon of refraction and reflection for the explanation. Huygens is an opponent of the particulate theory of light, he founded the fluctuation theory, in 1690 in the book "theory of light", wrote: "light is the same as sound, is propagated by a spherical wave surface." And he pointed out that every point reached by the vibration of light can be regarded as the center of vibration of a sub-wave, and the envelope of the sub-wave is the wavefront (wave front) of the propagating wave. Throughout the 18th century, the theory of the particulate flow of light and the theory of the fluctuation of light were roughly mentioned, but neither was very complete.

At the beginning of the 19th century, fluctuation optics took shape, represented by the works of T. Young and A. Fresnel. Young satisfactorily explained the "color of thin films" and the phenomenon of double slit interference. Fresnel supplemented Huygens' principle with Young's principle of interference in 1818, resulting in the Huygens-Fresnel principle known today, which satisfactorily explains the phenomena of interference and diffraction of light, as well as the linear propagation of light. In further studies, polarization of light and interference of polarized light were observed. In order to explain these phenomena, Fresnel assumed that light is a transverse wave propagating in a continuous medium (Ether). But the properties of an elastic solid had thus to be imposed on the Ether, which was inconceivable in such a nature, and even the recognition of the Ether failed to relate optical phenomena to other physical phenomena.

In 1846 Faraday discovered that the vibrating plane of light rotates in a magnetic field; and in 1856 W. Weber found that the velocity of light in a vacuum is equal to the ratio of the electromagnetic unit of the intensity of the current to the electrostatic unit. They indicate that there is a certain `internal relationship between optical and electromagnetic phenomena.

Maxwell's theoretical research around 1860 pointed out that changes in electric and magnetic fields cannot be confined to a certain part of space, but propagate at a speed equal to the ratio of the electromagnetic unit of current to the electrostatic unit, and light is such an electromagnetic phenomenon. This conclusion was confirmed by Hertz's experiments in 1888. According to Maxwell's theory, if c represents the speed of light in a vacuum, and v represents the speed of light in a transparent medium with dielectric constant ε and magnetic permeability μ, then there are:

c/v=(εμ)1/2

where c/v is the refractive index of the medium, so there are:

n=(εμ)1/2

The above formula gives the optical constant n and the electrical constant of the transparent medium. The above equation gives the relationship between the optical constant n and the electrical and magnetic constants ε and μ of a transparent medium. Maxwell's theory was a major step forward from previous theories in understanding the physical properties of light.

However, this theory could not account for the nature of the electric oscillators that produce frequencies up to the frequency of light, nor could it explain the dispersion of light caused by the change in refractive index with the frequency of light. It was only when H. Lorentz founded the electron theory in 1896 that the phenomena of luminescence and absorption of light by matter were explained, as well as the various characteristics of light propagation in matter, including the explanation of the phenomenon of dispersion. Lorentz's theory of the Ether is a vast and infinite immobile medium, whose only characteristic is that light vibration in this medium has a certain speed of propagation.

Lorentz's theory does not give a satisfactory explanation of such an important problem as the distribution of energy by wavelength in the radiation of a hot black body. And, if Lorentz's conception of the Ether were considered correct, the moving Ether could be chosen as a frame of reference, enabling one to distinguish absolute motion. In fact, in 1887, A. Meikleisen and other interferometers to measure the "Ether wind" to get the negative results, which shows that by the time of Lorentz's theory of electrons, people still have a lot of one-sided understanding of the nature of light.

In 1900, Planck borrowed the concept of discontinuity from the theory of the molecular structure of matter, put forward the quantum theory of radiation, that various frequencies of electromagnetic waves (including light), can only be determined by their respective discrete energy from the oscillator shot, this energy particles known as the quantum, the quantum of light known as photons. Quantum theory not only naturally explains the law of the distribution of the radiant energy of a burning body according to wavelength, but also raises the question of the interaction of light and matter in a completely new concept. Quantum theory gave new concepts not only to optics but also to physics as a whole, and its birth is usually regarded as the starting point of modern physics.

In 1905, Einstein used quantum theory in the photoelectric effect to give a very clear representation of the photon. In particular, he pointed out that when light interacts with matter, light is also the smallest unit of photons. In addition, at the end of the 19th century and the beginning of the 20th century, many experiments have well proved the quantum nature of light. 1905 September, the German "Annals of Physics" published Einstein's "on the electrodynamics of the moving medium" article. For the first time, the basic principles of special relativity were put forward. The paper clarified that the application of classical physics, which had been dominant since the time of Galileo and Newton, was limited to situations where the speed was much less than the speed of light, and that his new theory could explain the characteristics of processes associated with high-speed motion. He fundamentally abandoned the concept of Ether and satisfactorily explained the optical phenomena of moving objects.

Thus, at the beginning of the 20th century, light was proved to be an electromagnetic wave by interference, diffraction, polarization, and the optical phenomena of moving objects, on the one hand, and the quantum nature of light - its particulate nature - was proved beyond any doubt by thermal radiation, photoelectric effect, photopressure, and the chemistry of light, on the other hand.

The Compton effect, discovered in 1922, the Raman effect, discovered in 1928, and the hyperfine structure of the atomic spectrum, which was already experimentally available at that time, show beyond doubt that the development of optics cannot be independent of quantum physics.

The quantum concept of light in modern optics does not exclude the concept of fluctuations of light, but it is necessary to unify the two with the help of quantum mechanics and quantum electrodynamics, which were created and developed by Heisenberg, Schr?dinger, Dirac, Feinman, Schwinger, and Jinichiro Asanaga. The application of their theories can elucidate atomic, molecular and ionic spectra; can explain the effects of electric, magnetic and acoustic fields on spectra; and can establish the relationship between excitation conditions and spectral properties. The history of optics shows that the two most important fundamental theories in modern physics - quantum mechanics and special relativity - were born and developed in human research on light.