What is mode locked laser?

A mode-locked laser is a type of laser that generates ultra-short laser pulses with high peak power. This is achieved by locking the phase of the laser light to a particular mode within the resonant cavity of the laser.

Mode locking is typically accomplished by using a saturable absorber that allows short pulses of light to pass through while blocking longer pulses. When the light is allowed to build up in the cavity, it will eventually reach a point where it is phase-locked to the cavity modes and the laser will emit a train of ultra-short pulses.

Mode locked lasers are used in a wide range of applications, including optical communications, materials processing, and medical imaging. They are capable of generating pulses as short as a few femtoseconds, which is important for studying ultrafast processes in physics, chemistry, and biology.

However, mode locked lasers require precise tuning and stabilization of the cavity to maintain the mode locking. This can be challenging in practice, and often requires sophisticated electronics and control systems to maintain stable operation.