Electro-optical shutters technique in q switching

In my earlier articles I have discussed the basics of Q-switching and three of its techniques known as mechanical shutters, rotating reflector method and passive shutters. Toady I will discuss the one more following techniques of Q-switching:

Electro-optical Shutters.

To obtain faster switching, the suitable electro-optical effects of altering the refractive index of a cell by applying an electic field is used. Two such effects are:

i)   Pockels effect

ii)  Kerr effect

i) Pockels effect. Continue reading “Electro-optical shutters technique in q switching”

Q-switching: The rotating reflector and passive shutters techniques

Last time I have discussed the basics of Q-switching and one of its techniques known as mechanical shutters. Toady I will discuss two more following techniques of Q-switching:

The rotating reflector method.

In this method of Q- switching, one of the  end mirrors of the cavity is replaced with a total reflection prism which  spins rapidly around its axis set at right angle to the resonator axis. As the prism revolves, it  faces the cavity with its reflecting  side and makes the laser cavity quality  factor Q high for a short time. When  the prism is out  of  this  position, the Q value drops. As it revolves on further rotation, Q value drops to minimum. Continue reading “Q-switching: The rotating reflector and passive shutters techniques”

Q Switching

Q-switching is a technique used to produce a high output pulse. It is accomplished by using a device to prevent the reflection of photons back and forth  in the active medium. This produces a  higher population inversion in the  metastable state. Then suddenly the optical cavity is opened to permit a large fraction of stored energy to be emitted in the form of very intense pulse of laser radiation. Q-switched lasers produce pulses of  10 to 250 nanoseconds.

Q-switching is also known as Q-spoiling.

As the quality factor Q of a laser cavity shows the ability of the cavity to store energy, thus, high Q means that high energy can be stored  in the cavity and a low Q means that the cavity will rapidly dissipate its energy. As the technique of Q-switching involves switching the optical cavity quality factor Q from a low to a high value, therefore, it is known as Q-switching.

Techniques of the Q-Switching : Continue reading “Q Switching”