Output characteristics of distributed feedback 3.0 terahertz quantum cascade lasers

Area of Science:

• Physics
• Quantum Optics
• Terahertz Technology

Background:

• Quantum cascade lasers (QCLs) are semiconductor lasers emitting in the mid-infrared to far-infrared (terahertz) range.
• Distributed feedback (DFB) mechanisms enable single-mode operation and wavelength tunability in lasers.

Purpose of the Study:

• To prepare and analyze the output performance of DFB quantum cascade lasers (QCLs) operating at 3.0 THz.
• To optimize grating parameters for enhanced laser performance.
• To investigate the frequency stability and beam characteristics of the fabricated lasers.

Main Methods:

• Theoretical analysis to optimize distributed feedback grating parameters.
• Fabrication of 3.0 THz DFB QCLs.
• Experimental characterization of output power, threshold current density, side-mode suppression ratio, and frequency stability.
• Observation of beam characteristics.

Main Results:

• Achieved single-mode emission at 3.0 THz.
• Maximum output power exceeded 166 mW at 15 K.
• Threshold current density was 257 A/cm².
• Side-mode suppression ratio was greater than 15 dB.
• Frequency stability showed variation < 3 GHz with input voltage changes.
• Observed beam with distinct fast and slow axis features.

Conclusions:

• Optimized DFB QCLs demonstrate high output power and excellent single-mode performance at 3.0 THz.
• The lasers exhibit stable frequency operation and specific beam characteristics.
• Further improvements and potential applications in terahertz science and technology are promising.