July 27, 2026 -- Recently, a research team led by Prof. MENG Bo at the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences, has proposed a novel quantum cascade laser (QCL) featuring a Goblet-shaped waveguide architecture, achieving room-temperature low-power laser emission.

This work was published in the prestigious journal Laser & Photonics Reviews under the title "Low power dissipation goblet quantum cascade laser." The first authors are Master student ZHANG Lequan and PhD student LIU Peng, with Prof. MENG Bo serving as the corresponding author.

The mid-infrared spectral region, often referred to as the "molecular fingerprint region," hosts vibrational-rotational transitions of numerous gas and biomolecules, rendering it indispensable for applications in gas sensing, environmental monitoring, and medical diagnostics. However, mid-infrared quantum cascade lasers have long been constrained by high power dissipation, complex fabrication processes, and elevated costs—bottlenecks that severely limit the practical deployment of portable infrared systems.

The core design concept centers on selectively wet-etching the active region to create a waveguide cross-section where the active region width is substantially narrower than the top and bottom cladding layers, yielding a distinctive Goblet-like profile. This architecture offers three key advantages:

Process Simplification: The approach completely eliminates the semi-insulating InP (SI-InP) lateral regrowth process that is conventionally required for low-power devices, significantly reducing fabrication costs and improving yield.

Optimized Current Injection: The preserved wide upper cladding layer ensures uniform and efficient current injection into the active region.

Enhanced Thermal Management: The extended InP cladding layers provide additional heat dissipation pathways, effectively mitigating the thermal bottleneck imposed by the SiO₂ passivation layer.

The team fabricated and characterized over fifty Goblet-QCL devices with varying dimensions. Key achievements include:

Low Room-Temperature Continuous-Wave (CW) Power Dissipation: For a 1 mm × 3 μm device, the CW threshold power dissipation reaches approximately 1 W at room temperature (293 K), with the pulsed threshold as low as 0.85 W.

High Output Power: The device delivers over 27 mW of CW output power at room temperature; at cryogenic temperature (243 K), the maximum CW and pulsed output powers reach 83 mW and 130 mW, respectively.

Excellent Power Conversion Efficiency: The wall-plug efficiency (WPE) reaches 3.9% in pulsed mode and 1.6% in CW mode at room temperature, increasing to 6.4% and 4.9% at 243 K—performance comparable to that of buried-heterostructure devices.

The team conducted a 25-hour continuous-operation reliability test. Driven at the rollover current point, the device maintained a stable CW output power of 370 mW with a maximum power fluctuation of merely 1.9 mW, fully validating the thermal stability and structural robustness of the Goblet architecture under high electrical power injection.

Remarkably, the narrowest 2-μm-wide device exhibits stable single-mode emission across the entire current dynamic range, with a side-mode suppression ratio (SMSR) of approximately 20 dB and a current tuning rate of 0.14 nm/mA. This single-mode behavior arises from the elevated mode threshold induced by the reduced modal gain in the narrow waveguide, and is achieved without any wavelength-selective elements—offering a promising route toward on-chip integrated single-mode mid-infrared laser sources.

This research provides a laser source solution that simultaneously offers low cost, low power dissipation, and high reliability for emerging applications in portable mid-infrared sensing systems, high-speed free-space optical communications, and on-chip nonlinear photonics.