Jerry R. Meyer

Interband cascade lasers

Recent advances in midwave infrared interband cascade lasers (ICLs) include novel distributed feedback configurations, vertical-cavity surface-emitting lasers, light-emitting devices, frequency combs, dual-comb spectroscopy, and ICLs incorporated into photonic integrated circuits on silicon and III-V platforms.

Midinfrared vertical-cavity surface-emitting laser

We report a type-II antimonide midinfrared vertical-cavity surface-emitting laser. The emission wavelength of 2.9 μm is nearly independent of temperature (dλ/dT≈0.07 nm/K) and the multimode linewidth is quite narrow (3.5 nm). The pulsed threshold power at 86 K is as low as 22 mW for a 30 μm spot. Lasing is observed up to T=280 K, and the peak output power from a 600 μm spot exceeds 2 W up to 260 K. The differential power conversion efficiency is >1% at 220 K.

Mid-IR vertical-cavity surface-emitting lasers

We theoretically investigate the feasibility and potential performance of optically and electrically pumped vertical-cavity surface-emitting lasers (VCSELs) emitting in the mid-IR spectral region. Our model includes spontaneous, stimulated, and nonradiative recombination, numerical dispersion relations and optical matrix elements from a multiband finite-element algorithm, carrier and lattice heating, three-dimensional heat flow, electrical injection, photon propagation, and diffraction. Each modeled structure consists of a distributed Bragg reflector (DBR) semiconductor bottom mirror, a /spl lambda/, 2/spl lambda/, or 3/spl lambda/ optical cavity incorporating the type-II active region, and a dielectric top mirror through which the output beam is emitted. The optically pumped VCSEL structure with a 10-/spl mu/m-diameter spot is predicted to operate up to a heat-sink temperature of 250 K and to be capable of producing >2 mW of CW output power. Furthermore, by collimating the pump beam with a microlens array, gain-guided VCSEL arrays with output powers in the watt range should be attainable. Comparable powers and operating temperatures are predicted for patterned devices with electrical injection through annular contacts. By far the most attractive properties are expected for structures employing a type-II interband cascade active region with electron recycling. The simulation predicts single-element threshold currents of 150 /spl mu/A at 200 K and 1.1 mA at 300 K and CW output powers of 4.7 and 1.2 mW, respectively.

Mid–infrared ‘W’ lasers

We review recent progress in the development of mid–infrared (mid–IR) quantum–well lasers with type–II antimonide ‘W’ active regions. Optically pumped W lasers achieved continuous–wave (CW) operation nearly to room temperature, and CW output powers exceeding 0.5 W per facet at 77 K. Improvements in the differential quantum efficiency were obtained by increasing the effective number of passes of the pump beam through the active region in the optical pumping injection cavity configuration. Near–diffraction–limited beam quality was achieved in the mid–IR using the angled–grating distributed feedback (α–distributed feedback (DFB)) approach with a W active region. Single–longitudinal–mode operation was demonstrated by vertical–cavity surface–emitting lasers emitting at λ = 2.9–3.0 μm. Broadened–waveguide W diode lasers recently operated at room temperature in pulsed mode and up to 195 K CW. A slope efficiency exceeding unity was achieved using the interband cascade laser approach with a W active region.

Resonantly pumped optical pumping injection cavity lasers

An optical parametric oscillator is tuned to the resonance wavelength of the etalon in an optical pumping injection cavity (OPIC) laser with a type-II “W” active region, thereby minimizing the threshold pump intensity and maximizing the output slope efficiency. Previous OPIC experiments employed fixed-wavelength sources with only limited tuning available by adjusting the incident angle. Low threshold pump intensities of 330W∕cm2 at 100K and 14kW∕cm2 at 300K (where the output wavelength is 3200nm) were achieved. The energy conversion efficiency is found to decrease by over a factor of 100 when the pump wavelength is tuned from the resonance condition (1822nm at 300K) to only slightly off resonance (e.g., 1808nm).

Antimonide interband and intersubband mid-IR and terahertz lasers

Abstract Antimonide semiconductor lasers for the mid-infrared and terahertz spectral regions are considered. It is predicted that optically pumped interband type-II lasers will be advantageous at long wavelengths, out to λ≈100 μm . In the mid-IR, antimonide intersubband lasers should have higher gains and longer carrier lifetimes than InGaAs/InAlAs quantum cascade lasers, and hence have prospects for room-temperature cw operation. Spin-polarized antimonide intersubband lasers with applied magnetic fields are projected to display room-temperature cw emission at λ=16 μm .

Phase-Matched Second-Harmonic and Cascade Laser Mid-IR Sources

High-power mid-IR coherent light sources operating either at ambient or thermoelectric cooler temperatures are required for numerous applications such as IR countermeasures and communications, remote chemical sensing for pollution and drug monitoring, chemical process control, laser surgery etc. In this paper, we report the development of two novel mid-IR sources: an intersubband based second-harmonic generator with voltage-controlled phase-matching and an interband cascade laser (ICL).

Optical pumping injection cavity (OPIC) for high-efficiency mid-IR "W" lasers

We report a new optical pumping injection cavity (OPIC) approach that combines a high pump absorbance with long pump wavelength and a thin active layer. High absorbance is achieved by tuning an etalon cavity to the pump wavelength, which brings about multiple passes of the pump beam through the active region. A 12- 1/2 period distributed Bragg reflector (DBR) consisting of alternating AlAs/sub 0.08/Sb/sub 0.92/ and GaSb layers was grown onto the GaSb substrate. The 2/spl lambda//sub pump/ central cavity consisted of a 0.51 /spl mu/m thick GaSb spacer, a 100 /spl Aring/ AlAs/sub 0.08/Sb/sub 0.92/ hole-blocking layer, a l0-period InAs/GaSb/InAs/AlAsSb (17 /spl Aring//35 /spl Aring//17 /spl Aring//44 /spl Aring/) W active region, another hole-blocking layer, and another spacer. The OPIC pump cavity was completed by a 7-period top GaSb/AlAsSb DBR. Although the OPIC is resonant in the vertical direction at /spl lambda//sub pump/, at the mid-IR wavelength, the mirror stacks function as cladding layers and the spacers function as high-index separate confinement regions. Thus the laser operates in an edge-emitting configuration. Pumping was by 107 ns pulses from a 2.098 /spl mu/m Ho:YAG laser, operating at a repetition rate of 1 Hz.

High-temperature CW operation of optically-pumped W-lasers

We report the high-temperature cw operation of optically-pumped W-lasers (so named because of the shape of the conduction band minimum). The active region of the MBE-grown structure consists of 80 periods of 16/25/40 /spl Aring/ InAs-GaInSb-AlAs-AlAsSb clad on top and bottom. The cladding and active regions are lattice matched to the GaSb substrate.

Interband cascade and type-II superlattice mid-infrared lasers

We report recent theoretical and experimental progress toward efficient and practical mid-IR semiconductor lasers employing active regions with a type-II band alignment. Perhaps the semiconductor IR source with the greatest potential is the interband cascade laser (ICL), in which multiple photons are generated by each injected electron as it traverses a staircase-like quantum well structure.