Which of the following optical modules are used in commercial cases currently?

Optical modules are categorized based on their transmission distance and power budget. The most commonly used classes in commercial deployments are:

Class B+:Supports distances up to 20 km and is widely used in urban and suburban areas.

Class C+:Supports distances up to 40 km and is suitable for medium-range deployments.

Class D:Supports distances up to 60 km and is ideal for long-haul connections in remote areas.

ClassesEandFare either outdated or not commercially viable due to their limited use cases.

References:

ITU-T G.984 Standard - Optical Module Specifications

Huawei Optical Module Product Guide