Surface plasmon photonic structures in terahertz quantum cascade lasers.

Area of Science:

• Optics and Photonics
• Semiconductor Devices

Background:

• Terahertz quantum cascade lasers (TQCLs) are crucial for generating terahertz radiation.
• Controlling TQCL emission properties is essential for advanced applications.
• Surface plasmon modes in waveguides are key to TQCL operation.

Purpose of the Study:

• To investigate periodic scattering of surface plasmon modes as a method for controlling TQCL emission.
• To demonstrate the effectiveness of thin slits as scatterers for surface plasmons.
• To explore various device implementations utilizing this scattering technique.

Main Methods:

• Realizing scatterers as thin slits in the metal and top contact layer of TQCL waveguides.
• Employing surface plasmon modes that propagate along the waveguide.
• Fabricating distributed feedback resonators, second-order gratings, and distributed Bragg reflectors.

Main Results:

• Periodic scattering significantly controls the properties of TQCL emission.
• The thin slit scatterers provide larger coupling strengths compared to previous methods.
• Successful implementation in devices for distributed feedback, vertical emission, and enhanced facet reflectivity.

Conclusions:

• Periodic scattering of surface plasmon modes is an efficient technique for TQCL emission control.
• This method offers enhanced coupling and versatility for various device designs.
• The approach enables advanced functionalities like feedback-free resonators and improved reflectivity.