# Broadband monolithic extractor for metal-metal waveguide based terahertz quantum cascade laser frequency combs

## TL;DR

This paper introduces a monolithic broadband extractor for metal-metal waveguide terahertz quantum cascade lasers, significantly enhancing output power and spectral bandwidth for frequency comb applications.

## Contribution

It presents a novel monolithic extractor design that improves power output and bandwidth in terahertz quantum cascade lasers with metal-metal waveguides.

## Key findings

- Five-fold increase in output power
- Broadband operation up to 670 GHz
- Single-lobed far-field pattern

## Abstract

We present a monolithic solution to extract efficiently light from terahertz quantum cascade lasers with metal-metal waveguides suitable for broadband frequency comb applications. The design is optimized for a bandwidth of 500 GHz around a center frequency of 2.6 THz. A five-fold increase in total output power is observed compared to standard metal-metal waveguides. The extractor features a single-lobed far-field pattern and increases the frequency comb dynamical range to cover more than 50 % of the laser dynamic range. Frequency comb operation up to a spectral bandwidth of 670 GHz is achieved.