Monolithic Scalable Mid-Infrared Phase-Locked Laser Array

The technical objectives of this proposal are: 1) the design of 3.8-4.2 micron-emitting, active-photonic-crystal (APC) quantum-cascade (QC) lasers by using passive phase-locking in a monolithic structure in order to achieve multiwatt-range, diffraction-limited powers; and 2) the development of the key crystal- growth processes for realizing the proposed APC QC laser: the growth and characterization of QC active- region materials (i.e., InGaAs/AlInAs strained-layer superlattices) on virtual substrates. Novel deep-well (DW) QC lasers will be designed to suppress carrier leakage out of active regions, resulting in electro-optic characteristics with low temperature sensitivity. For achieving high coherent power at the chip level, a novel type of APC-type structure is proposed whose elements are DW-QC lasers emitting in the 3.8-4.2 micron region. The design will be for APC devices of built-in index step an order of magnitude higher than for conventional APC-QC devices, as to achieve stable-beam operation in CW operation to high coherent powers. For 3.8-4.2 micron-emitting devices the design will be for usable CW powers larger than 7 W delivered in diffraction-limited beams. A plan for monolithically scaling coherent power to the 50-100 W range and the economical fabrication of the proposed APC devices with high production yield will be developed.