Manipulating nanowires for single-mode lasers
HANGZHOU, China, and BEIJING – A single-nanowire laser has
been developed that, unlike earlier ones, which operated mostly in multiple modes,
operates in a controllable single mode.
Researchers from Zhejiang and Peking universities used a nanowire
between 50 and 75 μm in length and 200 nm in diameter to develop the breakthrough
laser, which emits a wavelength of about 738 nm.
To produce a nanowire that functions as a single-mode laser, the
scientists excited a looped nanowire with a pulsed laser. The looped nanowire doubles
as a loop mirror, reducing the lasing threshold and increasing the wire’s
reflectivity. Together, the low threshold and high reflectivity create a high-quality
lasing cavity in the nanowire.
By adjusting the loop size with fiber probes, the team tuned the
laser’s wavelength. When the loop size was reduced, the optical path of the
smaller lasing cavity caused the wavelength to change.
This single-mode laser could be used as a nanoscale coherent light
source for optical communications, sensing and signal processing applications.
A study of their findings was published online Feb. 15, 2011,
in Nano Letters (doi: 10.1021/nl1040308).
- optical communications
- The transmission and reception of information by optical devices and sensors.
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