The laser in the form of an eight is a fiber laser , the resonator of which is twisted into a loop that resembles an eight in shape. It is used to generate picosecond and femtosecond soliton-like pulses. A typical spectrum of such a laser consists of a broad central peak and several narrow side peaks located symmetrically relative to the central one. The amplitude of the latter is the same or slightly less than the amplitude of the central one. [1] .
Both eight-cavity resonator loops serve as Sagnac loops . An active fiber (a fiber whose core is doped with rare-earth ions serving as the active medium of the laser) is placed asymmetrically with respect to the cavity loops, which creates a nonlinear phase difference between counterpropagating waves and ensures mode synchronization when a certain threshold pump power is exceeded. [2] In 1992, a figure-eight laser was built, whose smaller loop was 1.6 m long and the larger one was 60.8. It generated pulses with a duration of 315 fs with an interval of 125 MHz. [3]
See also
- Ring resonator
Notes
- ↑ Fermann et al., 2002 , pp. 102-103.
- ↑ Agrawal, 2008 , pp. 181-182.
- ↑ Agrawal, 2008 , p. 215.
Literature
- Agrawal GP Applications of nonlinear fiber optics. - 2nd ed. - Academic Press, 2008. - Vol. 10. - 508 p. - (Optics and Photonis Series). - ISBN 9780123743022 .
- Ultrafast Lasers: Technology and Applications / Ed. by ME Fermann, A. Galvanauskas, G. Sucha. - CRC Press, 2002. - 800 p. - ISBN 9780824743499 .
Links
- Mode-locked Fiber Lasers: 1.5-μm Femtosecond Erbium Fiber Lasers Encyclopedia of Laser Physics and Technology . RP Photonics. Date of treatment August 12, 2011. Archived May 15, 2012.
- MK Islam and PL Chu. Stability Analysis of Mode Locked Figure-eight Fiber Laser . Progress In Electromagnetics Research Symposium. Date of treatment August 13, 2011.