Tunable terahertz quantum cascade lasers with external gratings.
We demonstrate a frequency tunable external cavity terahertz quantum cascade laser using an abutted antireflection-coated silicon lens to reduce facet reflection and as a beam-forming element, with an external grating providing frequency selective optical feedback. Angle tuning of the grating allows a single longitudinal mode of the laser ridge to be selected, resulting in discontinuous tuning over a 165 GHz range around a center frequency of 4.4 THz. Another device exhibited 145 GHz of total tuning with 9 GHz of continuous tuning near the longitudinal modes of the laser.
Lee
Alan Wei Min
AW
Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. awmlee@mit.edu
Williams
Benjamin S
BS
Kumar
Sushil
S
Hu
Qing
Q
Reno
John L
JL