Background

High capacity transmission in mobile and access networks has been increasing due to the growth of 5G communications and the expansion of mobile video services. This growth has presented some challenges to achieve increased capacity and to reduce the infrastructure cost of the transmission systems and optical fiber.
To address these challenges, FOC has developed a 30-km bidirectional 100G QSFP28 BiDi optical transceiver which can achieve 10 times the conventional transmission capacity and 2 times the optical fiber utilization efficiency.

Key features

・100G Bidirectional Transmission Reduces Fiber Operation Costs
In addition to using a high-speed transmission/reception device capable of 100Gb/s at a single wavelength, a WDM filter that multiplexes and demultiplexes the transmission/reception wavelengths has been incorporated into the QSFP28 package size to provide 100Gb/s bidirectional transmission.

As a result, while 10 units of 10G transceivers and 20 fibers were previously used for 100Gb/s transmission capacity, the transceiver count can be reduced from 10 to 1, the number of fibers used can also be reduced from 20 to 1, increasing the capacity of a single fiber and reducing fiber operating cost to 1/20 (Figure 1).

(Figure 1)　Fiber operating cost reduction

・Realization of 30 km transmission by LAN WDM wavelength and EML
For 20-km SMF transmission, using CWDM grid wavelengths was found to be suitable, however, for 30-km transmission, chromatic dispersion of fiber wavelengths and an increase of fiber loss were issues. To solve this problem, FOC has made it possible to achieve low wavelength dispersion by adopting a LAN WDM EML (Electro-Absorption Modulated Laser）device with a narrow wavelength interval and an external modulation method. In addition, by improving the optical output power of the transmission device, it achieved a longer 30-km distance for bidirectional transmission in a compact QSFP28 size, a world first.

FOC has already started supplying these transceiver product samples to customers and is targeting mass production in the second half of 2022.

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  QSFP28 BiDi transceiver Product line-up