•Tongzheng was established in Sep, 2010,belong to lgg group.•2500 square meter factory area.1400 sq meter clean room.•Manufactured products: Laser-diode(LD),Photo-diade(PD), components, optical module,optical cable assembly.•Vertically integrated with low cost manufacturing.Most of the materials are supported by brother companies, who has been provided ferrule,sheet metal,die casting products to telecom customers.•Main product application:Access, telecom backbone,metro area network, optical fiber exchange, optical fiber transmission relay, otpical commnication system and digital television.