In PON technology:Class A,Class B and Class C

Optical link budgets are determined by individual vendor’s active components: PON chip within the electronics, lasers, and receivers. The PON optic “class” has been defined as class A, B and C.

Traditional BPON equipment has always used class B optics. When looking at the link budget for the class B optics, one will find that the maximum link is set at 25dB. It was determined that some of the PON networks of 20km were actually stretching these budgets to the limit, and the active equipment manufactures were forced to increase these budgets to 26.5dB. with the advent of these increased budgets and the possible need to increase the split ratios of GPON, the class B optic were given an increase in the receiver photo detectors to allow for a 28dB loss budget. While still not in the class C optics range, these components were given the distinction of class B+ optics.

The key differentiation is that the cost of these Class B+ optics has not increased to the class C pricing while maintaining better PON loss characteristics. In the future, the need to transport to longer reaches (30km or 40km) and even higher split ratios(1:128) may force the equipment manufacturers to the class C optics.

More details, please send email to sissiy@sopto.com