@article { ISI:000180703000020,
	title = {Resonant second-order nonlinear optical processes in quantum cascade lasers},
	journal = {PHYSICAL REVIEW LETTERS},
	volume = {90},
	number = {4},
	year = {2003},
	month = {JAN 31},
	publisher = {AMERICAN PHYSICAL SOC},
	type = {Article},
	address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
	abstract = {We demonstrate an efficient intracavity nonlinear interaction of laser modes in a specially adapted quantum cascade laser. A two-wavelength quantum cascade laser structure emitting at wavelengths of 7.1 and 9.5 mum included cascaded resonant optical intersubband transitions in an intracavity configuration leading to resonantly enhanced sum-frequency and second-harmonic generation at wavelengths of 4.1, 3.6, and 4.7 mum, respectively. Laser peak optical powers of 60 and 80 mW resulted in 30 nW of sum-frequency signal and 10-15 nW of second-harmonic signal, both in good agreement with theoretical calculations.},
	issn = {0031-9007},
	doi = {10.1103/PhysRevLett.90.043902},
	author = {Owschimikow, N and C. Gmachl and Belyanin, A and Kocharovsky, V and Sivco, DL and Colombelli, R and F. Capasso and Cho, AY}
}
