Mid-Infrared Lasing in Lead Sulfide Subwavelength Wires on Silicon

Abstract

Vapor–liquid–solid (VLS) growth of nanoscale or subwavelength scale semiconductor wires (nanowires) has been proven to be an important and effective approach to producing high-quality, substrate insensitive photonic materials with a flexible and ever-expanding coverage of wavelengths for lasing and other photonic applications. However, the materials and lasing demonstrations have so far been limited to mostly ultraviolet to visible wavelengths, with a few exceptions in the short-wavelength infrared range. A further extension to longer wavelengths (such as mid-infrared, MIR) using narrower band gap semiconductors encounters severe challenges: the ever decreasing radiative efficiency due to the Auger and other nonradiative channels with wavelengths demands extremely high material quality and significantly narrows the material choices. This situation is very unsatisfactory, given many important applications that demand materials and lasers of subwavelength scales for MIR wavelengths in an integrated platform, especially on silicon. Here we report our results on lasing demonstration in MIR (3–4 μm) based on a unique combination of high-quality material growth on a silicon substrate and the choice of an intrinsically strong MIR material in lead sulfide (PbS). Lasing is demonstrated from single wires both on the original silicon substrate and on the sapphire substrates after transferring, with sizes of lasing wires down to below half of the normalized volume (volume of wires divided by the wavelength cubed) and operating temperature up to 180 K. Such subwavelength wire lasers could be important for a wide range of MIR applications on silicon-based integrated photonic platforms, such as chemical and environmental sensing, free-space communications, and many others.

Vertical Emitting Nanowire Vector Beam Lasers

“…This peak shifts toward shorter wavelength with increasing pump fluence due to band filling effects in the InGaAs QDs. 35,37 An F−P resonance peak centered at 980 nm appears at an excitation pump fluence of about 1 μJ/cm 2 per pulse. The intensity of this resonance peak increases as the pump power is increased and quickly dominates the entire emission spectrum.…”

Ultralow Threshold, Single-Mode InGaAs/GaAs Multiquantum Disk Nanowire Lasers

“…A broad PL spectrum of about 50 nm in width centered at 975 nm appears at low pump fluences. As the excitation pump fluence is increased, the PL spectrum blue shifts due to band filling effects. , When the excitation pump fluence is increased to 1.6 μJ/cm 2 per pulse, a narrow peak appeared at 959 nm. With a further increase in the pump fluence, the intensity of this narrow peak increases significantly and dominates the entire emission spectrum with clamping spontaneous emission becoming apparent.…”

Integrating a Semiconductor Nanowire Laser in a Silicon Nitride Waveguide

“…Although the current devices can only be operated at 10 K due to the increased lasing threshold, the NW could be embedded in more efficient external cavities based on SiN waveguides to address this issue, such as SiN waveguide Bragg grating reflectors with high reflectivity . With the advantages of possible wide-band operation wavelength of semiconductor NW lasers, − easy and large volume integration, and high mode coupling efficiency between NW laser and SiN waveguide, our strategy could provide a highly potential solution for SiN-based PICs with laser sources. Furthermore, different from constructing laser sources on a silicon photonic platform by direct heteroepitaxy, our integration architecture has no limits on the substrate, thus providing a universal solution for on-chip laser sources in large-scale passive PICs.…”