Cascade type-I quantum well diode lasers emitting 960 mW near 3 μm

Abstract

The cascade pumping scheme reduced the threshold current density of high power type-I quantum well GaSb-based λ ∼ 3 μm diode lasers down to ∼100 A/cm2 at room temperature. Laser heterostructures had single GaInAsSb quantum well gain stages connected in series by means of GaSb/AlSb/InAs tunnel junctions followed by InAs/AlSb electron injectors. Devices with densely stacked two and three gain stages and 100-μm-wide aperture demonstrated peak power conversion efficiency of 16% and continuous wave output power of 960 mW. Corresponding narrow ridge lasers demonstrated above 100 mW of output power. The experiment showed that the bandwidth of the gain and its rate of increase with current depended strongly on the thickness of AlSb layer separating electron injectors from quantum wells. The possible impact of electron injector interfaces and ionized impurities on the carrier scattering and recombination in the active quantum well is discussed.

Cascade Type-I Quantum Well GaSb-Based Diode Lasers

“…Lasers operating near 2 µm used 400 nm of Al 0.3 Ga 0.7 As 0.03 Sb 0.97 alloys on both sides of the active region to form a separate confinement heterostructure. Details of the laser heterostructure designs can be found in [9,15,16]. Wafers were processed either into 100-µm-wide deep-etched (through waveguide core) ridges for high-power operation or into double-step shallow-/deep-etched narrow ridges for single-spatial-mode operation.…”

“…Laterally coupled distributed-feedback 2.9-µm lasers for hydroxyl radicals spectroscopy were based on a similar two-stage cascade laser heterostructure and demonstrated CW power above 10 mW in a stable single spectral mode beam [11]. An increase in the number of cascades to three yielded high-power multimode λ~3-µm lasers with a record CW output power level of 960 mW from a 100-µm-wide aperture at room temperature [9]. It should be noted that type-I QW emitters based on standard ICL heterostructures with two n-claddings and operating at a similar wavelength were reported [12], but these devices were still demonstrated to have much lower output power levels.…”

“…Insert magnifies the parts of laser heterostructure responsible for electron transfer from valence band of QW1 to the conduction band of QW2. (b) CW light-current and power conversion characteristics measured at 17˝C for 100-µm-wide, 2-mm-long, anti-/high-reflection coated two-stage cascade and reference diode lasers [9]. Insert shows the cascade device emission spectra corresponding to the maximum power level.…”

“…We proposed and demonstrated a high-power GaSb-based type-I QW cascade diode lasers emitting near 3 μm at room temperature in a CW regime [9]. Figure 1a shows schematically the generic two-stage laser heterostructure band diagram.…”

Single-mode interband cascade lasers emitting below 2.8 μm

“…In conclusion, laser emission below 2.8 lm based on interband cascade lasers was demonstrated with a record value of the characteristic temperature T 0 of 67 K. Based on pulsed mode operation around room temperature in the wavelength range around 3 lm, the three earlier mentioned approaches can be compared in terms of threshold current densities: Cascaded type-I QW devices were published with around 100 A/cm 2 for quinary diode lasers 8,9 and with around 300 A/cm 2 for a superlattice design. 10 Based on QCL technology, threshold current densities of around 2.0 kA/cm 2 and 3.5 kA/cm 2 were achieved on the InP and InAs material system, respectively.…”