The concept of integrated optics was put forward by Dr. Miller of Bell Laboratories in 1969. Integrated optics is a new subject which studies and develops optical devices and hybrid optical electronic device systems using integrated methods on the basis of optoelectronics and microelectronics. The theoretical basis of integrated optics is optics and optoelectronics, involving wave optics and information optics, nonlinear optics, semiconductor optoelectronics, crystal optics, thin film optics, guided wave optics, coupled mode and parametric interaction theory, thin film optical waveguide devices and systems. The technological basis is mainly thin film technology and microelectronics technology. The application field of integrated optics is very wide, in addition to optical fiber communication, optical fiber sensing technology, optical information processing, optical computer and optical storage, there are other fields, such as material science research, optical instruments, spectral research.

First, integrated optical advantages

1. Comparison with discrete optical device systems

Discrete optical device is a type of optical device fixed on a large platform or optical base to form an optical system. The size of the system is on the order of 1m2, and the thickness of the beam is about 1cm. In addition to its large size, assembly and adjustment are also more difficult. The integrated optical system has the following advantages:

1. Light waves propagate in optical waveguides, and light waves are easy to control and maintain their energy.

2. Integration brings stable positioning. As mentioned above, integrated optics expects to make several devices on the same substrate, so there are no assembly problems that discrete optics have, so that the combination can be stable, so that it is also more adaptable to environmental factors such as vibration and temperature.

(3) The device size and interaction length are shortened; The associated electronics also operate at lower voltages.

4. High power density. The light transmitted along the waveguide is confined to a small local space, resulting in a high optical power density, which is easy to reach the necessary device operating thresholds and work with nonlinear optical effects.

5. integrated optics are generally integrated on a centimeter-scale substrate, which is small in size and light in weight.

2. Comparison with integrated circuits

The advantages of optical integration can be divided into two aspects, one is to replace the integrated electronic system (integrated circuit) with the integrated optical system (integrated optical circuit); The other is related to the optical fiber and dielectric plane optical waveguide that guide the light wave instead of wire or coaxial cable to transmit the signal.

In an integrated optical path, the optical elements are formed on a wafer substrate and connected by optical waveguides formed inside or on the surface of the substrate. The integrated optical path, which integrates optical elements on the same substrate in the form of thin film, is an important way to solve the miniaturization of the original optical system and improve the overall performance. The integrated device has the advantages of small size, stable and reliable performance, high efficiency, low power consumption and easy use.

In general, the advantages of replacing integrated circuits with integrated optical circuits include increased bandwidth, wavelength division multiplexing, multiplex switching, small coupling loss, small size, light weight, low power consumption, good batch preparation economy, and high reliability. Due to the various interactions between light and matter, new device functions can also be realized by using various physical effects such as photoelectric effect, electro-optical effect, acousto-optical effect, magneto-optical effect, thermo-optical effect and so on in the composition of the integrated optical path.

2. Research and application of integrated optics

Integrated optics is widely used in various fields such as industry, military and economy, but it is mainly used in the following aspects:

1. Communication and optical networks

Optical integrated devices are the key hardware to realize high speed and large capacity optical communication networks, including high-speed response integrated laser source, waveguide grating array dense wavelength division multiplexer, narrowband response integrated photodetector, routing wavelength converter, fast response optical switching matrix, low loss multiple access waveguide beam splitter and so on.

2. Photonic computer

The so-called photon computer is a computer that uses light as the transmission medium of information. Photons are bosons, which have no electric charge, and light beams can pass parallel or cross without affecting each other, which has the innate capability of great parallel processing. Photonic computer also has the advantages of large information storage capacity, strong anti-interference ability, low requirements for environmental conditions, and strong fault tolerance. The most basic functional components of photonic computers are integrated optical switches and integrated optical logic components.

3. Other applications, such as optical information processor, fiber optic sensor, fiber grating sensor, fiber optic gyroscope, etc.