C-Band Benchtop Narrow-Linewidth Frequency-Locked Tunable Semiconductor Laser

C-band benchtop narrow-linewidth frequency-locking tunable semiconductor lasers are primarily categorized by frequency selection/feedback mechanisms into grating-based types (e.g., Littrow/Littman external cavity, DFB/DBR), waveguide/interference types (e.g., micro-ring resonators, MZI), and hybrid integrated external cavity types