Heteroepitaxial growth and study of nonlinear optical materials for frequency conversion devices
Abstract
Compact, high-power, tunable laser sources for the mid and long-wave infrared (MLWIR) region are in great demand for a wide variety of military applications such as aircraft protection from heat-seeking missiles, long-range IR communications, or enhanced laser radar, as well for many civilian applications in areas such as security (airport scanners and remote sensing of chemicals and biological agents), industry (quality control, liquid levelers, real-time pedestrian detection), medicine (biopsy free cancer cell detection) and science. Since, the direct sources available in this spectral range, such as lead salts based lasers (1) or quantum cascade lasers (QCLs) (2) cannot satisfy requirements for power, tunability and frequency coverage, some alternative approaches such as frequency conversion of available direct sources via phase or quasi-phase matching (QPM) in nonlinear optical (NLO) materials could be a viable solution. However, all materials studied to date have achieved fundamental or technological limits. For example, birefringent crystals for phase matching such as AgGaSe2, ZnGeP2 (3) and KTP (4) have relatively small second order nonlinear susceptibility X((2)) and, in addition, suffer from the limitations such as thermal lensing damages and laser beam walk-off. The ferroelectric periodically poled lithium niobate LiNbO3 (PPLN) possesses, unfortunately, strong intrinsic absorption above 4 micrometer. This sets a limit for this, otherwise, convenient QPM material to be used only in a part of the first of the two atmospheric windows of transparency between 2-5 micrometer (5), leaving the other transparency window between 8-12 micrometer uncovered. In the same way, the leader in the non-ferroelectric QPM materials, GaAs, suffers from strong two-photon absorption (2PA) in the convenient pumping region of 1-1.7 micrometre (6), which is not a problem when using the same structured GaP.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2023
- Source ID
- FA86552117001
Entities
People
- Sebastian Lourdodoss
Organizations
- Air Force Office of Scientific Research
- Royal Institute of Technology
- United States Air Force