Madison, WI, United States
Madison, WI, United States

Time filter

Source Type

Botez D.,University of Wisconsin - Madison | Shin J.C.,Institute of Photonic Technology | Kirch J.D.,University of Wisconsin - Madison | Chang C.-C.,University of Wisconsin - Madison | And 2 more authors.
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2013

By tailoring the active-region quantum wells and barriers of 4.5-5.0-μm-emitting quantum cascade lasers (QCLs), the device performances dramatically improve. Deep-well QCLs significantly suppress carrier leakage, as evidenced by high values for the threshold-current characteristic temperature T0 (253 K) and the slope-efficiency characteristic temperature T 1 (285 K), but, due to stronger quantum confinement, the global upper-laser-level lifetime τ4g decreases, resulting in basically the same room-temperature (RT) threshold-current density Jth as conventional QCLs. Tapered active-region (TA) QCLs, devices for which the active-region barrier heights increase in energy from the injection to the exit barriers, lead to recovery of the τ4g value while further suppressing carrier leakage. As a result, experimental RT Jth values from moderate-taper TA 4.8-μm emitting QCLs are ∼14% less than for conventional QCLs and T1 reaches values as high as 797 K. A step-taper TA (STA) QCL design provides both complete carrier-leakage suppression and an increase in the τ4g value, due to Stark-effect reduction and strong asymmetry. Then, the RT Jth value decreases by at least 25% compared to conventional QCLs of same geometry. In turn, single-facet, RT pulsed and continuous-wave maximum wallplug-efficiency values of 29% and 27% are projected for 4.6-4.8-μm-emitting QCLs. © 1995-2012 IEEE.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase II | Award Amount: 253.75K | Year: 2015

The technical objectives of this proposal are: (1) demonstrate a 4.6 micron-emitting grating-coupled surface-emitting (GCSE) quantum cascade laser (QCL) designed for incorporation in an Active-Photonic-Crystal (APC) structure; (2) demonstrate a high-index-contrast APC-QCL edge-emitting structure, designed for incorporation of gratings; (3) demonstrate a GCSE-APC-QCL structure; (4) Develop monolithic aperture-filling optics for GCSE-APC QCLs; (5) demonstrate near-diffraction-limited-beam CW operation to > 15 W power, in the 4.5-micron wavelength range, from GCSE-APC QCLs; (6) Develop a plan for monolithically coherent-power-scaling GCSE-APC QCLs to powers exceeding 100 W CW. Step-taper-active (STA) QCLs will be used in the design since they suppress carrier leakage out of the QCL active regions, resulting in electro-optical characteristics much less temperature sensitive than in conventional QCLs; thus, allowing for significant increases in CW power and wallplug efficiency. The design will be for APC devices of a built-in index step at least an order of magnitude higher than in conventional APC-QCLs, as to achieve stable-beam operation in CW operation to high coherent powers with high wallplug efficiency. For 4.6 micron-emitting devices the goal is to obtain usable CW powers as high as 20 W, delivered in near-diffraction-limited beams.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 149.88K | Year: 2011

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.


Grant
Agency: Department of Defense | Branch: Army | Program: STTR | Phase: Phase I | Award Amount: 149.97K | Year: 2015

The technical objectives of this proposal are: 1) the design of high-index-contrast (HC) photonic-crystal (PC) THz, difference-frequency-generation (DFG) quantum cascade lasers (QCLs) with midinfrared pumps at 8 micron and 9 micron wavelengths; 2) design and demonstrate operation of a 4 THz DFG-QCL with the midinfrared pumps operating at 8 and 9 microns; and 3) Theoretically demonstrate the feasibility of HC-PC QCL structures with high, room-temperature THz performance. 8- and 9-micron-emitting HC-PC QCLs of a built-in index step an order of magnitude higher than in conventional PC QCL devices will be designed, as to achieve stable-beam operation in quasi-CW operation to high coherent average powers. An 8- and 9-micron-emitting, single-element QCL will be fabricated and used for experimentally demonstrating 4 THz generation at room temperature in pulsed operation. HC-PC QCL structures will be designed to emit at wavelengths of 8 and 9 microns, and be suitable for room-temperature, nonlinear-optical generation of THz radiation, via intracavity DFG, at both 1 THz and 4 THz. The overall design will be for generating 10 mW average power at 3-4 THz, and mW average power at 1-2 THz, delivered in diffraction-limited beams.


Grant
Agency: Department of Defense | Branch: Army | Program: STTR | Phase: Phase II | Award Amount: 749.71K | Year: 2012

The technical objectives of this proposal are: 1) Implement the design developed in Phase I for the realization of 8 micron-emitting active-photonic-crystal (APC) quantum-cascade (QC) lasers of 3 W average, diffraction-limited power and 15 % wallplug efficiency in quasi-CW operation; 2) Design and realize 4.6 micron-emitting APC QC lasers of 3 W CW diffraction-limited power and 15 % wallplug efficiency; 3) Identify commercial partners/customers and additional commercial markets; and 4) Perform studies for scaling the coherent power at 4.6 micron to the 50-100 W range. Tapered-active, deep-well QC lasers will be used, since they suppress carrier leakage out of active regions, resulting in electro-optic characteristics much less temperature sensitive than for conventional QC devices; thus allowing for significant increases in average power and wallplug efficiency. The APC-QC devices to be used have a built-in refractive-index step an order of magnitude higher than that for conventional APC-QC devices, and thus will be able to achieve stable, diffraction-limited beam operation in quasi-CW or CW operation to watt-range coherent powers with high wallplug efficiency.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 149.89K | Year: 2012

The technical objectives of this proposal are: 1) the design of 3.0-3.5 micron-emitting quantum cascade laser (QCL) structures grown on metamorphic-buffer-layer (MBL) substrates; 2) the realization of electroluminescent QCL structures on MBLs with emission in the 3.0-3.5-micron wavelength range. Novel tapered active-region (TA) QCLs will be designed to substantially suppress carrier leakage out of their active regions, in order to achieve electro-optic characteristics of low temperature sensitivity. Novel MBL-based approaches will be used for realizing low layer-strain levels for the structure of 3.0-3.5 micron-emitting intersubband-transition semiconductor sources. The design will be for QCLs able to achieve CW operation to at least 0.5 W at room temperature and with high beam quality. A development plan describing monolithic coherent-beam combining of TA QCLs for scaling the spatially coherent CW power to at least 5-10 W levels will be devised.


Grant
Agency: Department of Defense | Branch: Army | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2010

The technical objectives of this proposal are: 1) the design of 8 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 fabrication steps for realizing the proposed APC QC laser. Deep-well (DW) QC lasers will be used in the design since they suppress carrier leakage out of active regions, resulting in electro-optical characteristics much less temperature sensitive than for conventional QC devices; thus allowing for significant increases in average power and wallplug efficiency. At an emission wavelength of 8 microns the estimated increase in average power for a single QC laser is from 0.2 W to 0.5 W. For coherently scaling the power at the chip level, a novel type of APC-type structure is proposed whose elements are DW-QC lasers. 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 quasi-CW or CW operation to high coherent powers with high wallplug efficiency. For 8 micron-emitting devices the design will be for usable average powers more than 3 W, delivered in diffraction-limited beams.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 79.83K | Year: 2013

The technical objectives of this proposal are: (1) design a grating-coupled surface-emitting (GCSE) active-photonic-crystal (APC) 4.6 micron-emitting quantum-cascade laser (QCL) to deliver 15 W diffraction-limited CW power in the main lobe of the far-field beam pattern; (2) design a GCSE-APC QCL structure with monolithic aperture-filling optical elements for obtaining close to 90 % of the surface-emitted power into the main lobe of the far-field beam pattern; and (3) design a GCSE-APC QCL structure employing second-order gratings with chirped period for increasing the light-outcoupling efficiency and the device wallplug efficiency. Step-taper-active (STA) QCLs will be used in the design since they suppress carrier leakage out of the QCL active regions, resulting in electro-optic characteristics much less temperature sensitive than for conventional QCLs; thus, allowing for significant increases in CW power and wallplug efficiency. The design will be for APC devices of built-in index step an order of magnitude higher than for conventional APC-QCL as to achieve stable-beam operation in CW operation to high coherent powers with high wallplug efficiency. For 4.6 micron-emitting devices the design will be for usable CW powers as high as 20 W, delivered in diffraction-limited beams.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase II | Award Amount: 555.29K | Year: 2013

The technical objectives of this proposal are: 1) Design a metal/semiconductor grating-based (i.e., substrate-emitting) Grating-Coupled Surface-Emitting Distributed Feedback Quantum Cascade Laser (GCSE-DFB QCL) emitting at 4.6 microns with high beam quality; and 2) Demonstrate a GCSE-DFB QCL emitting at 4.6 microns with single-lobe-beam operation and high beam quality, under CW operation. It is the goal of this program to develop a GCSE-DFB QCL single-stripe device which will operate in a single, diffraction-limited lobe (both longitudinally and laterally) under CW operation to moderately high (~ 0.5 W) output powers. Tapered-active, deep-well QC lasers will be used, since they suppress carrier leakage out of active regions, resulting in electro-optic characteristics much less temperature sensitive than for conventional QC devices; thus allowing for significant increases in average power and wallplug efficiency.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase II | Award Amount: 199.98K | Year: 2014

The technical objective of this proposal is to demonstrate a Quantum Cascade Laser (QCL) emitting in the 3.0-3.5 & #181;m wavelength region, which employs a metamorphic buffer layer (MBL). It is the goal of this program to develop a QCL single-stripe device which will operate in a single, diffraction-limited lobe under room temperature continuous-wave (CW) operation to moderately high (~ 0.5 W) output powers. The use of the MBL allows for a lower-strain QCL active-region design compared with conventional approaches which employ InP substrates. Advanced conduction-band-engineered QC lasers will be used, since they allow virtual suppression of carrier leakage out of the devices active regions, resulting in electro-optical characteristics much less temperature sensitive than for conventional QCL devices; and thus allowing for significant increases in average power and CW wallplug efficiency.

Loading Intraband LLC collaborators
Loading Intraband LLC collaborators