Material Growth and Bandgap Engineering of DMS Crystals and Q-Switching and Isolation of Near/Mid IR Lasers

Development of reliable (Q-) switching and isolation materials is being sought for near-to-mid infrared lasers for safety, extended life and fiber optic communication. The voltage or E-field controlled (Q-) switching materials such as Pockels cells and liquid Kerr cells are not reliable for long term operation in tactica applications due to crystal surface (e.g., KDP, ADP) degradation by moisture or due to loss of index-matching fluid. Recently developed magneto-optic crystals such as the doped CdTe crystal exhibit a giant Faraday effect approximately 100 times greater than that of crystal quartz, optical fiber or zero-doped CdTe. Only a small magnetization current is needed for 90-degree rotation of the polarization plane. Because the crystal is water resistant the switch and isolator are reliable for long times; this allows systematic growth of the key crystal, Cadmium Manganese Tellurium (Cd1-xMnxTe), Diluted Magnetic Semiconductor (DMS). The insertion loss will be minimized by band-gap engineering and by carefully controlling the manganese content (x) so that the crystal will be transparent to the laser line of interest. A high-speed switching time on the order of nanoseconds is anticipated. This includes growth of large diameter, homogeneous DMS crystals at x<0.7, band-gap engineering pertinent to near and (Q-) switching performance test with appropriate laser sources. The expected result is a suggicient supply of DMS crystals for reliable and high speed (Q-) switching elements to operate at high peak powers.