Method and system for compact, multi-pass pulsed laser amplifier

A method of operating an optical amplifier, the method comprising:

• directing optical radiation having a first polarization state along an optical path;
• transmitting the optical radiation through a first polarizer having a polarization axis aligned with the first polarization state;
• transmitting the optical radiation through a Pockels cell, wherein no substantial change in the first polarization state of the optical radiation results from transmitting the optical radiation through the Pockels cell;
• amplifying the optical radiation;
• rotating the polarization state of the optical radiation from the first polarization state to a second polarization state orthogonal to the first polarization state;
• reflecting the optical radiation from a second polarizer having a transmission axis aligned with the first polarization state;
• rotating the polarization state of the optical radiation from the second polarization state to the first polarization state using the Pockels cell;
• amplifying the optical radiation;
• rotating the polarization state of the optical radiation from the first polarization state to the second polarization state;
• reflecting the optical radiation from the second polarizer;
• amplifying the optical radiation;
• rotating the polarization state of the optical radiation from the second polarization state to the first polarization state;
• and
• transmitting the optical radiation through the second polarizer.

A laser amplifier comprising:

• an input aperture operable to receive laser radiation having a first polarization;
• an output aperture coupled to the input aperture by an optical path;
• a polarizer disposed along an optical path, wherein a transmission axis of the polarizer is aligned with the first polarization;
• an optical switch disposed along the optical path, wherein the optical switch is operable to pass the laser radiation when operated in a first state and to reflect the laser radiation when operated in a second state;
• an optical gain element disposed along the optical path;
• and
• a polarization rotation device disposed along the optical path.

A method of amplifying optical radiation, the method comprising:

• transmitting the optical radiation through a first polarizer;
• amplifying the optical radiation;
• injecting the optical radiation into a closed loop;
• determining that the optical radiation is to be maintained in the closed loop;
• activating an optical switch;
• amplifying the optical radiation;
• injecting the optical radiation into the closed loop;
• determining that the optical radiation is not to be maintained in the closed loop;
• deactivating the optical switch;
• amplifying the optical radiation;
• and
• transmitting the optical radiation through an output aperture.