This paper describes a new configuration of the channeled spectropolarimeter and its application for the spectroscopic
measurement of Mueller matrix. The new configuration uses the channeled spectroscopic polarization
state generator (CSPSG) consisting of a polarizer and two high-order retarders. The channeled spectropolarimeter
using the CSPSG has features that up to four independent polarimetric parameters about a sample can be
determined simultaneously from a single channeled spectrum and that it is almost immune to the wavefront
perturbations induced by the sample.
To apply the channeled spectropolarimetry for the full measurement of Mueller matrix, the CSPSG is combined
with a rotating compensator spectropolarimeter. All elements of the spectroscopic Mueller matrix are
determined from four channeled spectra. Its feature is that it requires only one rotating component for the full
Mueller matrix measurement.
A novel configuration for the channeled spectroscopic ellipsometer (CSE) is presented. The channeled spectroscopic ellipsometry is a snapshot method for the spectrally-resolved polarization analysis. In this method, multiple-order retarders are utilized to generate a channeled spectrum carrying information about the wavelength-dependent multiple parameters of polarization of light. This method has a feature that it requires no mechanical or active components for polarization-control, such as a rotating compensator and an electro-optic modulator. In spite of these advantages, however, the previously proposed configuration of the CSE has a drawback that it is susceptible to the ray-direction variation introduced by the angular fluctuation of the ellipsometric sample. To overcome this drawback, an alternative configuration for the CSE has been developed. In this configuration, the multiple-order retarders are inserted between a light source and a sample, so that the measured results are not affected by the fluctuations due to the reflection from the sample. A compact sensing head whose size is 160mm(W)×53mm(H)×30mm(D) was realized using the new configuration, and applied for the snapshot measurement of the SiO2 films deposited on a Si substrate, with the acquisition time of 20 ms. The measured thicknesses of the SiO2 films are almost agree with the results from the rotating-compensator ellipsometer. The configuration that has the multiple-order retarders in the polarization-generating section can apply to other spectroscopic polarimeters to remove the influence of the ray-direction fluctuations due to the reflection or transmission from the sample.
A novel design of the channeled spectropolarimeter suited for stable operation is presented. An integrated polarization analyzing optics made of calcite is used together with a novel signal processing procedure to add the self-recalibration feature to the channeled spectropolarimeter. The recalibration of the system parameters and
the measurement of the state of polarization are made simultaneously using only the light under measurement. A multi-channel spectrometer is also employed to avoid the errors associated with the wavelength-axis drift. Elimination of the thermal disturbance is demonstrated experimentally.
We have demonstrated a Tm-Ho-codoped silica fiber laser pumepd by a third-stokes Raman Fiber Laser (RFL) at 1212 nm. RFL consists of Yb-double clad fiber laser (DCFL) as a pump, 1-km Single mode fiber (SMF) and cascated cavities made with fiber Bragg gratings (FBG). For the 30-cm-long Tm-Ho-codoped silica fiber, the output power of 400 mW is obtained at wavelength of 1790 nm (due to the laser radiations of Tm3+ ions). The optical-optical conversion efficiency and the slope efficiency are 18% and 23%, respectively. For the 270-cm-long Tm-Ho-codoped silica fiber, the output power of 450 mW is obtained at 1970 nm; this is the laser emission from Ho3+ ions. The optical efficiency is 18% and the slope efficiency is measured to be 31%. This is the highest output power ever reported for a Tm-Ho-codoped silica fiber laser.