Mid-infrared widely tunable single-mode interband cascade lasers based on V-coupled cavities

Area of Science:

• Optoelectronics
• Mid-Infrared Photonics
• Semiconductor Lasers

Background:

• Mid-infrared (MIR) lasers are essential for applications like spectroscopy and sensing.
• Interband cascade (IC) lasers offer efficient MIR emission but require precise mode control.
• Widely tunable single-mode lasers are highly desirable for advanced applications.

Purpose of the Study:

• To demonstrate widely tunable single-mode lasers near 3 µm.
• To utilize a type-II interband cascade (IC) structure for MIR laser development.
• To achieve mode selection using a novel V-coupler design.

Main Methods:

• Fabrication of V-coupled-cavity lasers based on a type-II IC structure.
• Deeply etched laser waveguides and cavity in a single etching step.
• Mode selection achieved via a half-wave V-coupler optimized for MIR IC structures.

Main Results:

• Demonstrated widely tunable single-mode operation near 3 µm.
• Achieved a tuning range of over 35 nm via injection current adjustment.
• Extended tuning range to 60 nm by combining current and heat-sink temperature adjustments.
• Obtained a side-mode suppression ratio (SMSR) up to 28 dB.

Conclusions:

• The V-coupled-cavity design enables effective mode selection for MIR IC lasers.
• The demonstrated lasers offer significant tuning ranges for MIR applications.
• This technology provides a promising platform for compact and tunable MIR light sources.