2 W high efficiency PbS mid-infrared surface emitting laser

Abstract

High efficiency laser operation with output power exceeding 2 W was obtained for vertical external-cavity PbS based IV-VI compound surface emitting quantum-well structures. The laser showed external quantum efficiency as high as 16%. Generally, mid-infrared III-V or II-VI semiconductor laser operation utilizing interband electron transitions are restricted by Auger recombination and free carrier absorption. Auger recombination is much lower in the IV-VI semiconductors, and the free-carrier absorption is significantly reduced by an optically pumped laser structure including multi-step optical excitation layers.

Temperature dependent band offsets in PbSe/PbEuSe quantum well heterostructures

“…From the fit of the experimental data, the normalized conduction band offset is determined as 0:4560:15 of the band gap difference, independently of Eu content up to 14% and temperature from 20 to 300 K. Lead salt heterostructures have been extensively used for fabrication of coherent mid-infrared light sources such as buried stripe lasers, 1,2 vertical cavity surface emitting lasers, 3,4 microdisk lasers, 5,6 photonic crystal lasers, 7 as well as external cavity disk lasers with tunable emission and high output powers. [8][9][10][11] In these devices, ternary lead salt alloys with Sr or Eu are usually employed as barriers for the quantum wells (QWs), providing a large tunability of the bands gaps E g as required for band gap engineering. As a result, room temperature mid-infrared laser operation in cw-mode has been achieved at wavelengths up to 4:3lm.…”

In-well pumped mid-infrared PbTe/CdTe quantum well vertical external cavity surface emitting lasers

“…9,12,13 A reasonable explanation is given by the large difference of the carrier confinement in these cases. For PbTe/CdTe (Eg ¼ 1.46 eV), the barrier height is much large compared to barriers made of ternary lead salt materials such as Pb 0.93 Sr 0.07 Se (E g ¼ 0.44 eV).…”

“…The barrier layers are made of ternary materials, such as PbXSe or PbXTe (X ¼ Sr, Eu). [12][13][14] The external cavity arrangement of VECSELs permits a simple optical pump scheme, where electron-hole pairs are generated in the spacer/barrier layers and then captured by QWs. Since for VECSLEs no doping is required, optical pumping leads to a substantial reduction of free carrier absorption in the mid-IR.…”

Optically pumped VECSELs: review of technology and progress

“…These gain mirrors benefit from utilization of AlAsSb/GaSb DBRs that offer an outstanding index contrast, but they possess poor thermal conductance. At wavelengths beyond 3 µm, VECSELs have been fabricated using PbSe or PbTe active layers grown on BaF 2 [83] or Si [119] substrates; the wavelength coverage of these gain structures extends from 2.65 µm to 6.5 µm [120][121][122]. However, they usually need low operating temperatures for lasing, though lasing at temperatures as high as 52 °C has been demonstrated [123].…”