Figure-8 laser

It is used for making pico- and femtosecond soliton pulses.

The typical spectrum of such a laser consists of a wide central peak and a few narrow lateral peaks that are placed symmetrically around it.

The active medium of the laser is optical fiber with its core doped with rare-earth ions.

It is placed asymmetrically with respect to the resonator loops to make a nonlinear difference in phase between opposite waves, ensuring mode locking.

[2] In 1992 a figure-8 laser was built with a smaller loop length of 1.6 m and a larger loop length of 60.8 m for generation of 315 fs pulses with repetition rate 125 MHz.

Fiber laser with figure-8 ring resonator. In : pumping. Out : emitting light. 1 : active fiber. 2 : polarizer. 3 : optical isolator. 4 WDM splitter. 50:50 splitter 50/50.