Continuous wavelength tuning in micromachined Littrow external-cavity lasers

Xuming Zhang, A. Q. Liu, Chao Lu, D. Y. Tang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

39 Citations (Scopus)


This paper presents the theory and experiment of the wavelength continuously tunable lasers, whose external cavities are constructed by the microelectromechanical systems (MEMS) technology. The theoretical study reexamines the wavelength tuning theory and adapts it to the MEMS tunable lasers under special concerns of the system properties such as short cavity length and pre-aligned component position. It is shown that in the MEMS Littrow lasers a mode-hop-free wavelength tuning requires a moving pivot, or in other words, a fixed pivot has only limited tuning range. In addition, it is also found that the wavelength dependence of the gain medium refractive index significantly affects the wavelength tuning range. Based on the theoretical study, a tuning structure is fabricated by the deep reactive ion etching (DRIE) on a silicon-on-insulator (SOI) wafer, and hybridly integrated with a gain chip and an optical fiber. The laser has dimensions as small as 2.0 mm × 1.5 mm × 0.6 mm, and can be tuned continuously over 30.3 nm at a resolution of 0.03 nm/V2. As a comparison, another MEMS tunable laser designed according to the conventional theory has only a tuning range of 5.9 nm.
Original languageEnglish
Pages (from-to)187-197
Number of pages11
JournalIEEE Journal of Quantum Electronics
Issue number2
Publication statusPublished - 1 Feb 2005
Externally publishedYes


  • Continuous wavelength tuning
  • External cavity tunable laser (ECTL)
  • Littrow grating
  • Optical microelectromechanical systems (MEMS)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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