Transmitter optical subassembly, optical component, optical module, and passive optical network system

An optical module, comprising:

• a transmitter optical subassembly, wherein the transmitter optical subassembly includes a substrate and a direct modulated laser disposed on the substrate, wherein a single-stage isolator, a polarization direction rotator, and an optical branching filter are disposed side by side on the substrate in a light propagation direction and wherein
• the polarization direction rotator is configured to adjust linearly polarized light to P-polarized light, and wherein the optical branching filter includes an optical splitter subassembly and a filter subassembly, and wherein an optical splitter film in the optical splitter subassembly is an optical splitter film with P polarization.

A passive optical network (PON) device, comprising:

• an optical module including a transmitter optical subassembly, wherein the transmitter optical subassembly includes a substrate and a direct modulated laser disposed on the substrate, wherein a single-stage isolator, a polarization direction rotator, and an optical branching filter are disposed side by side on the substrate in a light propagation direction and wherein
• the polarization direction rotator is configured to adjust linearly polarized light to P-polarized light, wherein the optical branching filter includes an optical splitter subassembly and a filter subassembly, and wherein an optical splitter film in the optical splitter subassembly is an optical splitter film with P polarization.