Optical transmitters are typically one of the following types EXCEPT:

LEDs are a well-established type of optical transmitter used in short-distance, lower-bandwidth multimode fiber applications due to their low cost and broad spectral output.

Short wavelength lasers (operating around 780-850 nm, similar in design to CD lasers) are used as optical transmitters in multimode fiber systems and are a recognized transmitter category.

VCSELs (Vertical Cavity Surface Emitting Lasers) are a widely deployed optical transmitter type used extensively in data center and LAN fiber applications at 850 nm.

Laser diodes are a primary class of optical transmitter used in both single-mode and multimode fiber systems for high-speed, long-distance transmission.

Overfilled Launch (OFL) is a measurement launch condition used when testing multimode optical fiber, describing how light is coupled into the fiber so that all propagating modes are excited - it characterizes a test setup, not a transmitter device. Optical transmitters are active light-emitting components (LEDs, laser diodes, VCSELs), while OFL describes the spatial and angular distribution of light entering the fiber during bandwidth or attenuation measurement.