Structure of optical fiber devices

Structure of optical fiber devices

Optical fiber devices have fiber type, rod lens type and planar type structures. Optical fiber type devices are made of optical fiber through grinding, polishing, hot melt taper or coating. The processing is relatively simple, without special materials, so the cost is low. Rod lens type device is made of rod lens or other micro optical elements necessary. Rod lens is a cylindrical lens with parabolic refractive index distribution in cross section and self focusing effect on transmitted light beam, also known as self focusing lens (Figure 1). This kind of lens is characterized by small focal length, large numerical aperture, small aberration, convenient processing and connection, and easy alignment. The collimating focusing parallel light path composed of two rod lenses with a length of 1/4 pitch is suitable for a variety of optical fiber devices. The planar device is made of lithium niobate and other substrate materials by integrated circuit technology. It is characterized by small size and good anti external interference performance. It is a primary form of integrated optical devices, also known as thin film optical waveguide passive devices.