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 are different methods of mode locking?

Methods for producing mode-locking in a laser may be classified as either ‘active’ or ‘passive’. Active methods typically involve using an external signal to induce a modulation of the intracavity light.

What is Q-switching explain different types of 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 is mode locking essential?

Mode locking is the most important technique for generating pulses with picosecond and femtosecond durations. Each time the pulse hits the output coupler mirror, a part of its energy is emitted, so the laser output is a regular pulse train. The gain medium replenishes the pulse energy in each roundtrip.

What does Q switch do?

When the Q-Switch laser is used to treat your pigmented lesions including age spots, freckles, sunspots and some birthmarks, it targets the melanin in the superficial layer of your skin. When the pigmented lesion absorbs the light energy from the Q-Switch Laser it gets converted into heat.

What is Q switch laser treatment?

Q -Switch laser creates an invisible beam of light that specifically targets the brown pigment or melanin present in the dark spots without having any affect on the surrounding skin. The pigment absorbs the laser energy and gets fragmented within the skin’s tissues, thereby giving you smooth and even skin tone.

How often can I do Q switch laser?

Time saving: Usual Q-Switched laser treatments take 12 – 15mins and is done once every 3-4 weeks. This saves time compared to no-frills laser treatments which only last for 1-2mins each and you would be advised to do these treatments up to 3-7 times a week.

What is Q-switching and mode locking?

Q-Switching and Mode Locking. If the energy stored in the dominant mode is very large, we get high Q. Q – switching means maintaining the population inversion to a very high value above the threshold population.

What is the pulse repetition period of a mode locked laser?

The pulse repetition period corresponds to the cavity round-trip time (typically several nanoseconds). The average power of a mode-locked laser is of the same order of magnitude as that of continuous-wave lasers. In fact, in contrast to Q-switched lasers, these can also reach a steady state like continuous-wave lasers.

What is a “mode lock”?

The term “mode-locking” comes from the analysis of the various frequencies. A laser operating under these conditions will emit over several different frequencies due to the rapid modulation of the modulator. They are also imposed by the optical cavity, spaced out by : the longitudinal modes of the cavity.

What does Q-switched mean?

Q-switched Mode Locking. Q-switched mode locking is an operation regime of a passively mode-locked laser where the intracavity pulse energy undergoes large oscillations, related to a dynamic instability (undamped relaxation oscillations).