Current Projects

Difference Frequency Generation in Quantum Cascade Lasers: Dual wavelength quantum cascade lasers are designed with an integrated nonlinear mixing region. The interaction of the 5um and 9um (in this case) lasers in this mixing region is expected to generate light at the difference frequency of the two lasers. Such a device offers the possibilty of expanding the spectral range of current InP based QCLs, and offers a route to room-temperature generation of THz emission.

Dual-Wavelength Quantum Cascade Lasers with Two Optical Transitions in Each Active Region: a two-well QC laser design that used the second- and first-excited states of the constituent quantum wells of the active region—in contrast with the first-excited and ground states, as in conventional QC lasers. This excited state design has the potential for a higher gain coefficient and thus lower threshold current due to a larger optical dipole matrix element and wider active region wells that reduce surface roughness scattering.

High-performance Quantum Cascade Lasers: Device heating is a serious problem associated with Quantum Cascade (QC) lasers, which limits their performance especially in high-duty cycle and continuous-wave operation. By optimizing internal laser design, material growth and external device packaging, the performance of QC lasers can be improved dramatically. The ultimate goal is to develop uncooled, room-temperature, continuous-wave, high-power QC lasers in the Mid-IR, which is desirable for many practical applications.

Mid-IR emission from InAs Quantum Dots: Taking advantage of the three-dimensional quantum confinement in InAs QDs, we are designing, growing, and characterizing mid-IR emitters using QDs as the optical active region. Results thus far include: mid-IR Electroluminescence from unipolar QD devices and anisotropically polarized, multiple wavelength emission from InAs QDs in the mid-IR.

Mid-IR negative refraction without a magnetic resonance:The potential for subwavelength resolution and planar lensing has led to a recent surge of interest in negative refractive index materials. The typical scheme for creating such materials is to employ overlapping electric and magnetic resonances. Similar effects, however, can be obtained by using an electric resonance and an anisotropic dielectric function. This method is used to create mid-infrared negative index materials which require only a monolithic growth process.

Quasi Chaotic Trace Gas Sensor: Quantum Cascade (QC) lasers are ideal light sources for midinfrared sensing applications. Not only can they be tailored to a unique frequency range in the midinfrared band, but they also have a narrow linewidth and high optical power. Combining QC lasers with novel implementation schemes (such as efficient optical resonators) could lead to robust and highly sensitive chemcial detectors.

More projects coming soon!