Modern optics of optics

Due to the discovery and development of laser, a series of new branches of optics have emerged and developed rapidly. As early as 19 17, Einstein discussed in detail that there are two forms of material radiation when studying atomic radiation: one is spontaneous radiation; The second is the stimulated radiation generated by external photon-induced excitation. It is predicted that stimulated radiation can produce monochromatic light with very high brightness propagating in a certain direction. Because of these characteristics, since T. Mayman first manufactured the ruby laser in 1960, the research of laser radiation has made laser science and laser technology develop rapidly, and opened up many new branches closely related to laser itself. In addition to quantum optics, there are nonlinear optics, laser spectroscopy, ultra-strong and ultra-fast optics, laser materials and laser physics.

In classical wave optics, medium parameters are considered to be independent of light intensity, and optical processes are usually expressed by linear differential equations. However, many new phenomena have been discovered in the case of strong laser passing through. If it is found that the refractive index is related to the laser field intensity, the refraction angle of light at the interface between the two media will also change when the beam intensity changes. Self-focusing and self-defocusing of light beams; After light waves pass through a certain medium, the frequency changes, resulting in frequency doubling, sum frequency and difference frequency. All these phenomena belong to the study of nonlinear optics. The laser has been able to generate a light source with high directivity, high monochromaticity, adjustable polarization and frequency, and it is possible to obtain ultra-short pulses. High-resolution spectroscopy, picosecond (10- 12s) ultrashort pulses and tunable laser technology have profoundly changed classical spectroscopy and developed it into laser spectroscopy. At the same time, high-power femtosecond ultrashort pulse laser can be obtained, and the research on the interaction between this kind of laser and matter has developed into ultra-strong and ultra-fast optics. These new disciplines have become an important means to study the microstructure and micro-dynamic process of matter, providing unprecedented new technologies for the study of the structure and dynamic process of atomic physics, molecular physics, condensed matter physics, molecular biology and chemistry.

With the development of laser science and technology and the application of laser in many fields, new requirements are put forward for the performance of laser materials and corresponding laser devices. The basic problems involved in the development of new light sources and lasers have become an important part of modern optics, and their development trends are wavelength expansion and frequency modulation, optical pulse width compression, miniaturization and solidification of devices. The development of the past decades shows that laser science and laser technology have greatly promoted the development of physics, chemistry, life science and environmental science, and formed a number of very active emerging interdisciplinary subjects, such as laser chemistry, laser biology, laser medicine and information optics. At the same time, laser has been widely used in precision measurement, remote sensing and telemetry, communication, holography, medical treatment, material processing, laser guidance and laser-induced nuclear fusion.