Design and analysis of terahertz surface-emitting distributed-feedback lasers with circular metal grating

S. F. Yu, X. F. Li

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

3 Citations (Scopus)


Circular surface-emitting quantum-cascade lasers (QCLs) are good candidate to provide high-power low-divergent single-mode terahertz (THz) waves. These devices employ the metallic cladding layer and 2nd-order circular metal grating to provide surface-coupling mechanism and ultra-high light confinement to improve the lasing efficiency. Under such a big index contrast in metal grating, high-order diffracted waves cannot be overlooked, leading to dramatic change of the transverse modal distribution with the variation of grating duty cycle. Therefore, the conventional coupled-wave technique used for small-index contrast grating becomes inapplicable for this investigation. To solve this problem, we express the field distribution as a Floquet-Bloch expansion of Hankel functions to take into account the high-order diffraction waves. First, the coupled-wave equations of transverse-magnetic mode are derived under the infinite-length approximation. The detailed transverse-mode characteristics of symmetric and anti-symmetric modes supported in the circular waveguide as well as the effects of device parameters are analyzed. Based on the results of infinite-length assumption, the coupled-mode equations of finite-length device are then derived, which allows us to investigate the threshold and modal characteristics of the considered THz surface-emitting circular QCLs. It is observed that the proposed structure has the potential to realize vertical THz radiation with beam quality of subwavelength dimension.

Original languageEnglish
Title of host publicationINEC 2010 - 2010 3rd International Nanoelectronics Conference, Proceedings
Number of pages2
Publication statusPublished - 3 Jan 2010
Externally publishedYes
Event2010 3rd International Nanoelectronics Conference, INEC 2010 - Hongkong, China
Duration: 3 Jan 20108 Jan 2010

Publication series

NameINEC 2010 - 2010 3rd International Nanoelectronics Conference, Proceedings


Conference2010 3rd International Nanoelectronics Conference, INEC 2010

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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