Understanding QSFP28: The Building Block of Modern Connectivity

The QSFP28 form factor is known for its small size and high performance, allowing for dense packaging of optical modules in switches and routers. This density is crucial for data centers that need to maximize the number of connections per rack unit while minimizing space and power consumption.

 200GBase-QSFP-DD ZR4 80KM (SMF, 1310nm,LC)

Advancing to 200G: Doubling the Capacity

Achieving 200G throughput involves several technical advancements. One key innovation is the use of advanced modulation techniques, such as PAM4 (Pulse Amplitude Modulation 4-level), which allows for higher data rates over the same channel bandwidth. PAM4 encodes data using four distinct signal levels, effectively doubling the data rate compared to traditional NRZ (Non-Return-to-Zero) encoding.

Extending Reach to 80KM: Long-Distance Transmission

One of the most remarkable features of the QSFP28 200G 80KM solution is its ability to transmit data over long distances without significant signal degradation. Achieving 80KM reach is no small feat and requires sophisticated optical technologies.

Coherent Optics: The Enabler of Long-Distance Transmission

Coherent transmission systems employ digital signal processing (DSP) to compensate for these impairments in real-time, ensuring that the signal remains intact over long distances. The use of coherent optics also enables the use of higher-order modulation formats, further increasing the data capacity of the fiber.

To maintain signal integrity over 80KM, optical amplifiers are essential. These amplifiers, typically based on Erbium-Doped Fiber Amplifiers (EDFAs), boost the signal strength without converting it to an electrical signal. This all-optical amplification process minimizes latency and ensures that the signal remains strong and clear throughout its journey.

Dispersion, the spreading of light pulses over distance, can severely degrade signal quality. To counteract this effect, dispersion compensation modules (DCMs) are used. These modules adjust the refractive index of the fiber to counteract the dispersion, ensuring that the signal remains sharp and well-defined over long distances.

Conclusion