US 4,174,504 A · Apparatus and method for cavity dumping a Q-switched laser

Abstract

A laser having a gaseous gain medium capable of continuous wave operation and including an etalon with a Stark active gas disposed therein, adapted for providing submicrosecond pulses is disclosed. A method of utilizing the Stark effect to tune rapidly an etalon to form an output mirror having a variable reflectivity to Q-switch and cavity dump the optical flux within a laser to provide an output pulse of laser radiation having a submicrosecond pulse width, typically variable between fifty and three hundred fifty nanoseconds, at a pulse repetition frequency up to twenty-five kilohertz is disclosed. A laser typically having a carbon dioxide gain medium adapted for continuous wave operation includes a grating defining one end of the laser resonator and an output mirror defining the other end wherein the output mirror is an etalon formed with two mirrors containing a switching cell having a Stark active gas disposed therein. A voltage applied to the switching cell rapidly transforms the highly transmissive state of the output mirror to a highly reflective state to Q-switch the laser. Terminating the voltage rapidly transforms the highly reflective state of the output mirror to its original highly transmissive state to cavity dump the Q-switched optical pulse. Controlling the width, fall time and repetition rate of the voltage pulse controls the pulse intensity, pulse width and pulse repetition frequency of the laser output pulses.

Claims27

Dependent claims

A laser having an optical axis and adapted for providing submicrosecond pulses of infrared radiation comprises:

a first cavity including a gaseous gain medium capable of continuous wave operation defined at one end by a first reflector and at the other end by a second reflector;
a second cavity defined at one end by the second reflector and at the other end by a third reflector wherein the first cavity and the second cavity are symmetrically disposed about the optical axis in optical line of sight communication with each other and wherein the second reflector and the third reflector define a Fabry-Perot etalon, which functions as the output mirror of the laser;
a switching cell symmetrically disposed about the optical axis within the second cavity;
means for applying an electric potential across the switching cell with the resulting electric field in a direction transverse to the optical axis;
means for tuning the first cavity to obtain maximum optical flux of a specific wavelength of radiation oscillating within the first cavity;
and
means for varying the separation between the second reflector and the third reflector to tune the second cavity to the wavelength of radiation capable of oscillating within the first cavity.

4 more elements

A method of Q-switching and cavity dumping a continuous wave laser to provide laser pulses having submicrosecond pulse widths comprising:

providing a laser having a first cavity including a gaseous gain medium adapted for continuous wave operation and a second cavity defined at one end by a second reflector and at the other end by a third reflector wherein the second and third reflectors form a Fabry-Perot etalon;
providing a switching cell within the second cavity for maintaining a gas capable of exhibiting a Stark effect within the switching cell such that the gas and the reflectors defining the etalon cooperate to provide an output mirror having an effective reflectivity capable of being changed quickly for Q-switching and cavity dumping optical flux within the laser to provide pulses of laser radiation;
generating a continuous discharge within the gain medium to provide radiation oscillating within the first cavity;
controlling the wavelength of radiation oscillating within the first cavity with a first reflector defining one end of the first cavity to obtain resonance with the gas within the switching cell;
controlling the separation between the second and third reflectors to obtain a low reflectivity of the output mirror when the gas within the switching cell is unactivated to allow transmission therethrough of the radiation within the first cavity;
activating the gas within the switching cell by applying a voltage across the switching cell with the resulting electric field in a direction transverse to the optical axis of the laser to produce a Stark effect within the gas to provide an output mirror having a high reflectivity capable of Q-switching the first cavity;
maintaining the voltage across the switching cell until a desired optical flux within the first cavity is obtained;
and
terminating the voltage to cavity dump the optical flux within the first cavity to provide a pulse of laser radiation having a submicrosecond pulse width.

6 more elements

Dependencies are inferred from the claim text.

Apparatus and method for cavity dumping a Q-switched laser

Life of this patent

Apparatus and method for cavity dumping a Q-switched laser

Life of this patent

Abstract

Claims27