cavity was folded at approximately 45 degrees using a 40 reflecting oc as the folding mirror at approximately 180 mm from the front of the laser crystal a 82 reflecting mirror was used as the second hr the fe 2 znse sample was placed on this side as a passive q switch the pulse repetition rate was reduced to 4 hz to deal with thermal lensing problems using this setup enabled maximum q switched single pulse energy of 13 mj with 65 ns fwhm using 30 j of pump energy similar results on cr er ysgg cavity q switching were obtained with the use of single thermally diffused fe znse crystals as well as with hot pressed ceramic fe znse and thin films of fe znse grown by pulsed laser deposition thus we propose these fe 2 znse materials for use as a passive q switch particularly for er lasers further fe 2 zns having similar spectroscopic properties to fe 2 znse is known to have the larger bandgap 3 84 vs 2 83 ev better mechanical and optical damage characteristics better overlap of absorption band with the cr er ysgg lasing wavelength higher cross section of absorption at 2 8 u03bcm as well as lower thermal lasing dn dt.