Spectral width constraints this, defined as -3dB (half-power) or -20dB (1% power) bandwidth. DFB (Distributed Feedback) lasers in optical transceiver modules use -20dB width. In coherent systems, linewidth (related to frequency stability) is key, convertible to spectral. Standards specify length, width, height, and slot positions, ensuring plug-and-play compatibility. Common form factors include SFP (Small Form-factor Pluggable), QSFP (Quad Small Form-factor Pluggable), and OSFP (Octal Small Form-factor Pluggable). Mentioning a type like QSFP-DD instantly implies. Optical modules are crucial for today's communication systems as they convert electrical signals into light signals for rapid data transfer. Understanding their key parameters isn't just technical jargon – it's critical for ensuring compatibility, performance, and reliability in your data center. The transmission rate range of a single-fiber unidirectional optical module is 125 Mbit/s to 5 Gbit/s, and that of a single-fiber bidirectional optical module is 125 Mbit/s to 2. An. The core technical parameters of optical modules include: transmission rate, encapsulation, transmit optical power, receive sensitivity, transmission distance, center wavelength, optical interface type, operating temperature, maximum power consumption, etc. Let's introduce them one by one.