The 780nm Polarization Maintaining In-Line Variable Optical Attenuator (PM In-Line VOA) is used to precisely adjust the power of 780nm optical signals while ensuring that the polarization state (Polarization Maintaining, PM) of the optical signal remains unchanged. It adopts an in-line structure and can be directly integrated into the optical fiber system. It is widely used in the fields of optical fiber sensing, quantum optics, laser systems and bio-optics research.