Passive Optical Devices for 5G Application(Part I)

With the rise of 5G technologies and massive deployment of 5G base stations, wireless access of terminals with high speed and large capacity is realized. Meanwhile, the traffic in optical fiber network increases rapidly. It is predicted that the current optical fiber network will become the bottleneck of information exchange in the future 12-18 months. The upgrading of optical fiber network is urgent. The representative trend is that the technologies for long-haul network (LHN) will be sunk to metropolitan area network (MAN), including DWDM (Dense Wavelength Division Multiplexing), ROADM (Reconfigurable Optical Add-Drop Multiplexer) and coherent receiving techniques. This paper discusses some of the passive optical devices for the coming 5G applications.

1. CDC ROADM Based on MCS
The demand for increasing bandwidth promotes the upgrading of all-optical network (AON). As key parts of AON, the market of ROADM and related passive optical devices is expected to grow rapidly. In the nodes of optical fiber network, any wavelengths can be downloaded/uploaded via ROADMs. With the rapid growth of Internet traffic, the traditional ROADM nodes can’t meet the requirements. The new generation of ROADMs are required to be colorless, directionless and contentionless (CDC ROADM).

MEMS Optical Devices — MEMS VOA

MEMS technologies are widely employed in optical fiber communication system. The combination of MEMS and optical technologies is usually named MOEMS (Micro-Opto-Electro-Mechanical Systems). The most widely applied MOMES devices include VOA (Variable Optical Attenuator), OS (Optical Switch), TOF (Tunable Optical Filter), DGE (Dynamic Gain Equalizer), WSS (Wavelength Selective Switch) and OXC (Optical Cross Connect).

VOA is widely employed in optical fiber communication system for optical power equalization. Among the variable approaches, MEMS VOAs are characterized by small size, low cost and easy fabrication. There are mainly two types of MEMS VOAs in applications, MEMS shutter and MEMS mirror. The first is usually thermally actuated and the second is usually actuated by electrostatic force.