Modular PbSrS/PbS mid-infrared vertical external cavity surface emitting laser on Si

Abstract

A mid-infrared vertical external cavity surface emitting laser (VECSEL) based on undoped PbS is described herein. A 200 nm-thick PbS active layer embedded between PbSrS cladding layers forms a double heterostructure. The layers are grown on a lattice and thermal expansion mismatched Si-substrate. The substrate is placed onto a flat bottom Bragg mirror again grown on a Si substrate, and the VECSEL is completed with a curved top mirror. Pumping is done optically with a 1.55 μm laser diode. This leads to an extremely simple modular fabrication process. Lasing wavelengths range from 3–3.8 μm at 100–260 K heat sink temperature. The lowest threshold power is ∼210 mWp and highest output power is ∼250 mWp. The influence of the different recombination mechanism as well as free carrier absorption on the threshold power is modeled.

Design of Optically Pumped PbS-Based Mid-Infrared Surface Emitting Lasers

“…SrS/PbS short-period superlattices (SPSLs) with monolayer SrS are useful for the optical excitation layers and barrier layers in the MQWs. The SPSL has higher carrier mobility compared with PbSrS alloy owing to smaller alloy scattering, and the higher mobility is useful to decrease free carrier absorption [4,5]. Figure 1 shows the band gap of the PbSrS SPSL, and the band gap of PbSrS alloy with the same SrS content.…”

“…Figure 5 shows an optically pumped tunable mid-infrared laser structure. Tunability is obtained by slightly modulating the space w between the two mirrors (w < 0.1mm) [4]. A high power diode laser is available for excitation source in near infrared region, and mid-infrared laser optically pumped with the near infrared light has a high potential for the tunable laser application.…”

“…Optical pumped lasers are useful to decrease optical losses by free carrier absorption, and vertical external cavity surface emitting lasers (VECSELs) are useful in tunable laser operation [3]. We recently prepared optically pumped PbS based double heterostructure (DH) and multiple quantum well (MQW) structure VECSELs [4,5]. The MQW laser operated in high efficiency and high power at -70°C with external quantum efficiency of 16% and maximum pulsed output power of 2W.…”

Mid-Infrared Lasing in Lead Sulfide Subwavelength Wires on Silicon

“…36 PbS lasers have been studied in various geometries from edge-emitting to surfaceemitting lasers. 37 Electrically driven continuous wave (CW) lasers 38 and high quantum efficiency high output power lasers 39 have also been realized in the PbS diode with emission wavelengths at around 4.3 μm and operated at a cryogenic temperature. For MIR lasers at a higher operation temperature, the Pb 1−x Sr x S/PbS double-heterostructure was adopted in electrical injection design, and the laser temperature was raised to 245 K in pulsed operation mode and 174 K in CW operation mode with the emission wavelength around 3 μm.…”

“…40 Optical pumped PbS lasers have also been demonstrated from the cleaved PbSSe material at 150 K, 41 Pb 1−x−y Cd x Sr y S/PbS double-heterostructure lasers at 240 K, 42 to the most recent report demonstrating the Pb 1−x Sr x S/PbS multiquantum-well (MQW) vertical-cavity surface-emitting lasers (VCSELs) at 283 K in CW operation. 37,43 All of these lead salt-based MIR lasers, however, are substantially larger than the wavelengths involved, and subwavelength scale lasers in these wavelength ranges are yet to be developed. In fact, no MIR laser in subwavelength sizes has been reported, to the best of our knowledge.…”