How do you get mode locking?
Active mode locking involves the periodic modulation of the resonator losses or of the round-trip phase change, achieved e.g. with an acousto-optic or electro-optic modulator, a Mach–Zehnder integrated-optic modulator, or a semiconductor electroabsorption modulator.
What is the use of mode locking?
Mode locking is a technique used to obtain ultrashort pulses from lasers. Lasers that are mode locked are capable of producing pulses with pulse widths in the order of sub-pico seconds, or even femtoseconds.
What is the difference between Q switching and mode locking?
Dear Xinyang, passive Q-switching takes place in both cases as in time of “giant” pulse generation so in time of mode locking. Mode locking needs the saturated absorber with relaxation time less then round trip time in the given cavity while the giant pulse generation develops better with slow relaxing absorber.
What is meant by Q switching?
Q switching is a technique for obtaining energetic short (but not ultrashort) light pulses from a laser by modulating the intracavity losses and thus the Q factor of the laser resonator. The technique is mainly applied for the generation of nanosecond pulses of high energy and peak power with solid-state bulk lasers.
Why Q switching is needed in some laser?
Initially the laser medium is pumped while the Q-switch is set to prevent feedback of light into the gain medium (producing an optical resonator with low Q). The net result is a short pulse of light output from the laser, known as a giant pulse, which may have a very high peak intensity.
What is mode-locked fiber laser?
A technique for raising the possible pulse energy and/or for lowering the pulse duration of a mode-locked fiber laser is used in stretched-pulse fiber lasers [5, 8, 9, 13, 19, 22], also sometimes called dispersion-managed fiber lasers.
How does Q switching work?
What is passive Q switch?
Passive Q switching is an alternative technique, where the active modulator is replaced with a saturable absorber (a passive Q switch). There are other saturable absorber crystals for other wavelengths and semiconductor saturable absorber mirrors (SESAMs) for various operation wavelengths.
