Event calendar D-PHYS

Date	31.03.2017
Time	14:00-16:00
Place	ETH Zürich, Hönggerberg HPF G 6
Speaker	Sarah Houver
Area of expertise	Physics
Host	Dep. Physik
Contact	Johnson
Abstract	Since the development of lasers in the 1960s, nonlinear optics with near infrared (NIR) beams has been widely explored thanks to these powerful and coherent sources. In the terahertz (THz) and Mid-Infrared (MIR) domains from 5 μm to 100 μm (3 meV to 200 meV), the lack of reliable sources has strongly limited investigations on THz nonlinear optics experiments. At the end of 1990s, the first THz nonlinear experiments demonstrated nonlinear frequency mixing1 between a NIR beam and a THz beam from a Free Electron Laser (FEL). Quantum Cascade Lasers (QCL) are compact powerful laser sources, operating throughout the MIR and THz regions. They are based on nanometric semiconductor layers and rely on intersubband transitions in semiconductor quantum wells. Since their first demonstration in 1994 for MIR QCLs2 and in 2002 for THz QCLs3, the performances of these devices have increased dramatically. Their intracavity powers can approach today those used in FELs. These developments are promising for the application of QCLs to THz nonlinear optics experiments and to study the interaction of strong THz fields with condensed matter systems. In this seminar, I will present THz nonlinear optics studies4, using QCLs simultaneously as sources for THz radiation as well as the nonlinear medium. We show how the optical nonlinearities of the system can be significantly enhanced through interband resonant excitations, permitting the generation of THz sidebands without considerations of phase matching. These experiments have been recently extended to MIR QCLs5, excitation wavelengths in the telecom range, and sideband generation up to room temperature. This paves the way for potential applications of resonant nonlinearities to optical wavelength shifting and ultrafast modulation transfer for telecommunications.

Date

31.03.2017

Time

14:00-16:00

Place

ETH Zürich, Hönggerberg
HPF G 6

Speaker

Sarah Houver

Area of expertise

Physics

Host

Dep. Physik

Contact

Johnson

Abstract

Since the development of lasers in the 1960s, nonlinear optics with near infrared (NIR) beams has been widely explored thanks to these powerful and coherent sources. In the terahertz (THz) and Mid-Infrared (MIR) domains from 5 μm to 100 μm (3 meV to 200 meV), the lack of reliable sources has strongly limited investigations on THz nonlinear optics experiments. At the end of 1990s, the first THz nonlinear experiments demonstrated nonlinear frequency mixing1 between a NIR beam and a THz beam from a Free Electron Laser (FEL). Quantum Cascade Lasers (QCL) are compact powerful laser sources, operating throughout the MIR and THz regions. They are based on nanometric semiconductor layers and rely on intersubband transitions in semiconductor quantum wells. Since their first demonstration in 1994 for MIR QCLs2 and in 2002 for THz QCLs3, the performances of these devices have increased dramatically. Their intracavity powers can approach today those used in FELs. These developments are promising for the application of QCLs to THz nonlinear optics experiments and to study the interaction of strong THz fields with condensed matter systems. In this seminar, I will present THz nonlinear optics studies4, using QCLs simultaneously as sources for THz radiation as well as the nonlinear medium. We show how the optical nonlinearities of the system can be significantly enhanced through interband resonant excitations, permitting the generation of THz sidebands without considerations of phase matching. These experiments have been recently extended to MIR QCLs5, excitation wavelengths in the telecom range, and sideband generation up to room temperature. This paves the way for potential applications of resonant nonlinearities to optical wavelength shifting and ultrafast modulation transfer for telecommunications.

Resonant nonlinear optics in quantum cascade lasers