Feature

Ultrashort Pulse Fiber Lasers

Irl N. Duling III

For years people have been looking for a compact, electrically efficient, inexpensive source of optical pulses less than one picosecond in duration for scientific investigation, optical probing, and, more recently, for high bit rate communication or computing systems. The early promises of modelocked diode lasers fell prey to low reliability and large intrapulse frequency chirp. When the first singlemode rare-earth-doped optical fiber was drawn in 1973, no one could predict the impact that this development would eventually have. Since then, we have seen fiber become the preferred method of communications transmission, and the rare-earth-doped optical fiber the preferred method of optical amplification. It is not surprising, then, that there has also been a significant effort to use the wide bandwidth of the rare-earth-doped fiber gain transition to make a laser to produce ultra-short pulses. In its most elegant form, this laser would be all fiber, diode laser pumped, and capable of producing pulses of less than half a picosecond.