Optical passive devices is an important part of the communication device, but also the other optical components indispensable application areas. There are mainly four categories of Optical Passive.
(A) Active Fiber Optic Cable Connector
Fiber optic cable connector is connected to two active optical fiber to form a continuous optical path and can be repeated assembly and disassembly of passive components; also has the fiber optic cable with active devices, fiber optic cable and other passive components, fiber optic cables and systems and instrumentation carry out activities connections. Active connector along with the development of optical communication development, has now formed a complete range, a wide variety of systems products, fiber applications are indispensable, the most widely used component of the foundation.
Their function can be divided into the following sections: Connector plugs, fiber jumpers, converters, inverters, etc. These components may be used alone as the device, a component can be used together. In fact, an active connector is used to refer two connector plug plus a converter.
Optical attenuator is a certain amount of optical power can attenuation device. Optical attenuator can be broadly divided into fixed and variable types. Fixed attenuator and variable attenuator of the main indicators of its attenuation accuracy, precision, and stability or repeatability, as well as applicable wavelength region.
A fixed optical attenuator fixed amount of attenuation of the optical path of the light energy is mainly used for its excellent temperature characteristics. Debugging the system, commonly used in analog optical signals through a fiber attenuation and the corresponding relay station or decrease in the optical power of the room to prevent the optical receiver saturation; also be calibrated for an optical measuring instrument calibration.
For different line interface, you can use different fixed attenuator; if the interface is a pigtail type available pigtail type optical attenuator welded to the optical path between the two sections of fiber; If you are debugging the system connector interface converter or inverter-type fixed attenuator. In practical applications often require attenuation amount of the optical attenuator can be changed with the user needs. Therefore, the variable attenuator wider range of applications. For example, EDFA, CATV optical system design margin of the actual system is not exactly the same, the optical power margin of the system BER assessment, to prevent the receiver is saturated, it must be inserted in the system variable optical attenuator, another , fiber optics (such as a power meter or OTDR) measurement, calibration will also use the variable attenuator. From the perspective of market demand, on the one hand, the optical attenuator development toward miniaturization, serialization, low price direction. On the other hand, due to the common type optical attenuator, optical attenuator is development direction toward high-performance, intelligent optical attenuator, high return loss optical attenuator.
(C) Optical Switch
Optical switch is an optical path control device, the optical path switching plays a role in the optical fiber transmission network and a variety of optical switching systems, computer control can be achieved spectral exchange, to achieve between the terminals, between the center terminal and the distribution of information and exchange intelligence; in the ordinary optical transmission system, an optical path for the active and standby switching can be used in optical fiber, optical devices and optical fiber sensor network test, the optical fiber transmission systems, measuring instruments or the sensing system is stable and reliable easy to use.
CATV optical network in order to ensure uninterrupted operation of cable systems, should be equipped with a backup optical transmitter, an optical transmitter is working when a failure, the use of optical switch can be in a very short time (less than 1ms) to Backup optical transmitter access system to ensure it is working properly.
According to its operating principle, the optical switch can be divided into mechanical and non-mechanical two categories. Mechanical optical switch optical fiber or optical components by moving the optical path changes, currently on the market are generally mechanical optical switch, the advantage of low insertion loss, typically less than 1.5dB; high isolation, typically greater than 45dB, and without polarization wavelength effects. Non-mechanical optical switch is to rely on electro-optic effect, magneto-optical effect, sound and light effects and thermo-optic effect to change the refractive index of the waveguide, the optical path is changed, which is a new technology, the advantages of this type of switch: switch time is short, Small size, easy integration of optical or electro-optical integration; deficiencies are large insertion loss, isolation is low.
(D) WDM Multiplexer and Demultiplexer
Optical wavelength division multiplexing (WDM) technology in an optical fiber multiple wavelengths of light simultaneously transmitted carrier signal, and each optical carrier by FDM or TDM mode, each carrying multiple analog or digital signals. The basic principle is the sending side optical signals of different wavelengths are combined (multiplexed), and is coupled to the same fiber optical cable for transmission, the receiving end turn these combined signals at different wavelengths separated ( demultiplexing), and further processed to recover the original signal into a different terminal. Therefore, this technology called optical wavelength division multiplexing, short wavelength division multiplexing technologies.\