Passive optical Components/Devices FAQ

1. What is the passive optical device?
   
   Optical passive device is a kind of optical device that does not require a source of energy for its operation. Its work principle follows the optic geometry theory and optic physics theory. All the technical data, calculation formula and test methods are associated with the fiber optics and integrated optics.



2. How to classify the Optical Passive Devices?
   
   Passive optical devices can be classified by the technical process and the functionality. According to the manufacturing technical process, they can be classified as fiber passive optical devices and integrated passive optical device. Based on their functionality, they also can be classified as optical connector, amplifier, attenuator, power splitter, WDM devices, isolator, switch and so on.



3. What are the technical data to evaluate the passive optical devices?
   
   The evaluation technical data includes insertion loss, reflective loss, operation bandwidth, ripple, wavelength passband, channel passband, channel spacing, extinction ratio, switch rate and so on. The technical data are varied for different devices. But most passive optical devices require low insertion loss, high reflective loss, and wide bandwidth.



4. How to evaluate the reliability of a passive optical device?
   
   The reliability is evaluated by how the device performance changed in various environments such as in high/low temperature, high/low temperature cycle, shock, vibration, high-temperature aging test, humidity, and salty fog test. According to the requirement of related standards, the less change the optical technical data has, the higher reliability the device has.



5. What is EDFA?
   
   EDFA is Erbium Doped Fiber Amplifier, which is a kind device that began to use in the optical transmission system since '90 and brought a revolution to the optical fiber communication technology. The development of the EDFA is mainly based on the research for the application of 1.55um wavelength active optical devices. The prophase research is focus on the optical fiber laser and lanthanide doped optical fiber. Then they found that the erbium doped optical fiber can achieve optical amplification and the operation wavelength is corresponding to the 1.55um transmission wavelength. So the EDFA is realized based on this research fruit.



6. What is the EDFA for CATV? How is its application?
   
   Accelink EDFA-TV Series is design to use in CATV. It is installed before the CATV transmitter to amplify the output optical power and reallocation it to various transmission trunk line. When the trunk line is diverged, the EDFA can be installed before the divergence as line amplifier to compensate the divergence loss.



7. How to monitor the EDFA in the optical transmission network management system?
   
   As a function module in the whole system, EDFA has two ways to adopt into the network management system. One is to transmit the performance data and alarm signals of the EDFA into the network management system via the EDFA 232C interface, and then reach uniform management, display and treatment. The second way is to send the switch data to the network management system via the EDFA switch information interface. The two ways are all used in the engineering application.



8. What is EDFA Gain Module/Block Series for DWDM? How is its application?
   
   DWDM technology is the most effective way to expand the optical communication capability today. EDFA Gain Module/Block series for DWDM are the key components in the DWDM transmission system. It can effectively solve the insertion loss that caused by the mux/demux and make the relay to be easy in the DWDM system. Due to its 40nm operation bandwidth, EDFA can amplify different optical signals with multiply wavelengths at the same time. It can be conveniently used in DWDM system to compensate various optical power losses.



9. What are EDFA modules? What are their advantages?
   
   EDFA modules are integrated EDFAs, which have optic-electric integrated EDFA modules and optical gain module. EDFA module has the features of compact size, low power loss, and easy to be used. They can be easily installed in various application systems, such as SDH rack, CATV box, and DWDM system rack, according to user's specific application requirements.



10. What is the difference among the single mode connector, multi-mode connector and optical data connector?
    
    The optical fiber/cable of the Single mode optical fiber/cable connectors is single mode with core diameter of 9um. They are used in the single mode optical fiber/cable systems.
    The optical fiber/cable of the multi-mode optical fiber/cable connectors is multiple mode with core diameter of 50um. They are used in the multi-mode optical fiber/cable systems.
    The optical fiber/cable of the data optical fiber/cable connectors is data fiber with core diameter of 62.5um. They are used in the data optical fiber/cable systems.



11. What is optical attenuator? What types it has?
    
    Optical attenuator is the component used to reduce the optical power level of an optical signal. The basic types of optical attenuators are continuously variable, step-wise variable and fixed.



12. What is the attenuation range of the miniature VOPA? What is it used for?
    
    The attenuation range is 0~25dB. It is often used with the corresponding single-mode optical connector to adjust the optical power for the small range optical communication system, optical data communication network.



13. What is the optical coupler? What are the technologies to make the optical couplers?
    
    The optical coupler is a component to combine the optical signals in a particular couple area and then split them again. The most often used technologies are optic components combination, Fused Biconic Tapered (FBT), and Planar Lightwave Circuit (PLC).



14. What is the FBT coupler? What are its main features?
    
    The FBT coupler is made by closing two or more bare optical fibers in a specific way, fusing them in a high temperature environment and drawing their two ends at the same time, and finally forming a specific biconic tapered waveguide structure in the heating area. It can realize the combination and split of the transmission optical power, and has the features of low insertion loss, good directivity, stable environment, flexible control, and low cost.



15. What is WDM coupler? What is the WDM device? What are the basic types of WDM device?
    
    WDM coupler is a coupler to split the optical signals according to their wavelength. WDM device is a passive optical component to combine and split the optical signal wavelength.
    The basic types of WDM have Thin Film Filter (TFF), Optical Grating, Array Waveguide Grating (AWG), and Optical Fiber Grating.



16. What is optical isolator? What are its basic types?
    
    Optical isolator is a passive device to prevent return reflection along a transmission path. In its operation range, it has low power loss in the transmission direction and high power loss in the return reflection direction. The basic types of optical isolators have polarization dependent, which includes single stage and dual stage, and polarization independent. They can also be divided into online type and mini-type according to their application.



17. What is the difference between polarization dependent isolator and polarization independent isolator?
    
    The basic difference of the two isolators are that the previous one largely dependent on the input optical polarization, and be fit for using with lasers and other polarization devices. The second one is almost not affected by the input optical polarization, and be fit for using in the transmission systems.



18. What are the features of PMS-X portable power meter?
    
    It is an intelligent power meter which is controlled by a micro-processor and has a large 4 digit LCD screen. The power meter has various functions including auto-clear, auto-close, auto-change measurement and switch, value convert, measurement of the optical attenuation value in the transmission path, multi-wavelength measurement and low battery alarm.



19. What is the SOF-X stabilized light source used for?
    
    The stabilized light source can works in 850nm, 1310nm, 1550nm wavelengths with LED, LD and DFB-LD luminescence devices. It has the features of high and stable output power, and be fit for using in the research, manufacturing and engineering measurement for the optical communication, optical measurement, optical sensing, optical gyroscope, optical sub-network and optical devices.



20. What are the features of the FOM-X optical multi meter? What are the basic types of FOM-X multi meter?
    
    FOM-X Optical Multi Meter is an intelligent optical measurement multi meter, which integrates with the optical power meter and the stabilized light source, be controlled by microprocessor, and has multiple functionalities. It can be used as optical power meter and stabilized light source separately, as well be an integrated test system. It has the features of good anti-shock, anti-vibration and anti-knock. The FOM-X multi meter has five types, including FOM-A-85, FOM-A-131, FOM-A-155, FOM-B-131 and FOM-B-155, where FOM mean optical multi meter, A and B mean LED and LD, and 850,131and 155 mean the operation wavelength of the luminescence devices.



21. What is the FOM-X Multi Meters used for?
    
    It can be used in the research, manufacturing and engineering for the optical communication, optical measurement, optical transmission, optical CATV, optical cable engineering, optical devices measurement and other optical fiber application fields.