The analysis of two reflection spectra measuring the reflected power without and with reflection at the backside of a very thick substrate, as described in a previous paper [1], is used for implanted LiNbO3 samples. In the first case the profile of refractive index in the implanted layer can be evaluated for extra‐ordinary and ordinary light polarization. The measurement with reflections from the backside of the sample gives information about the amount and dispersion of absorption in the implanted layer. The decrease of this absorption by a thermal annealing at TA = 670 K is also clearly seen by the analysis.
In the theoretical description of reflection and transmission coefficients through a system with a layer much thicker than the wavelength the fluctuations of the thickness Δd/d and the spectrometer resolution Δλ/λ must be taken into consideration. The connection between the measured averaged values and the reflection and transmission coefficients from the front and back sides into the substrate is given by a Fourier sum. The total averages correspond to the summation over all light intensities caused by multiple incoherent internal reflections inside the substrate layer. As a special result of this analysis the measurement of the absorption in a thin layer by only reflection measurement will be demonstrated in a following paper. For smaller fluctuations the distribution function or better its Fourier components can also be measured by the analysis of the remaining interference effects.
We report on a hybrid monitoring strategy, which makes use of quartz crystal monitoring and broadband optical monitoring data in application to the deposition of chirped mirrors for the near infrared spectral region. We present a short description of the basic monitoring concept, the experimental setup, and the data elaboration facilities of the developed optical monitoring system OptiMon. Although being flexible enough to be implemented into different types of deposition system, we focus here on the application of our monitoring system for coating preparation with Advanced Plasma Source (APS) assisted electron beam evaporation. Chirped mirrors have been prepared using SiO2 and Ta2O5 as low and high index materials, respectively. The layers are characterized by in-situ transmission spectroscopy, ex-situ transmission and reflection spectroscopy, and white light interferometry to determine the group delay dispersion GDD. Basing on characterization results, we demonstrate and discuss the relative benefits of the developed monitoring strategy
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