Third harmonic generation in a Quantum Cascade laser with monolithically integrated resonant optical nonlinearity.

We present third harmonic generation from an InGaAs/AlInAs Quantum Cascade laser based on a three-well diagonal transition active region with an integrated third-order nonlinear oscillator. The device displays pump radiation at lambda ~ 11.1 mum and third order nonlinear light generation at lambda ~ 3.7 mum as well as second harmonic generation at lambda ~ 5.4 mum.