Optical fiber system for the high resolution resonant Raman spectroscopy at 3He temperature in a high magnetic field

Abstract

A high-resolution resonant Raman spectroscopy system has been developed by using optical fibers and applied to the spin-flip Raman scattering experiment in CdZnTe/ CdZnMnTe quantum wells at 3He temperature in a high magnetic field up to 14 T. Excitation light from an external cavity laser diode or Ti:sapphire laser was introduced into the liquid 3He chamber by using polarization maintain fiber, and was incident on the sample at the angle of 45 degree through a GRIN collimation lens and a prism to deflect the reflected light from the luminescence/scattering detection pass. Luminescence and scattered light were collected efficiently into the bundled multi-mode fibers through a high NA objective lens and introduced into the slit of a 1.26 m single grating spectrometer equipped with a multi-channel CCD detector and a photon counter. The fiber system provides a convenient way to investigate the spin dynamics in an ideal environments; ultra-low temperature and radiation-free condition. Furthermore, the system is more sensitive than the conventional system utilizing a cryostat with the optical windows where multiple Fresnel loss and the small numerical aperture degrade the sensitivity. © 2006 IOP Publishing Ltd.