OptiLayer allows you to specify a stack having period with varying optical thicknesses: $\left(\left(a\cdot iL+b\right)H\left(c\cdot iL+d\right)L\right)^n$ where $$a, b, c, d$$ are continuous variables , $$iL$$ is layer number in the design. More complicated example. You can achieve a narrow bandwidth of a standard quarter wave stack by shifting the ratio of high and low index values of a half wave pair in the stack: $\left( aH \; \left(2-a\right)L\right)^{(N-1)/2} aH$ where $$a$$ is the fractional quarter wave thickness and $$N$$ is the total number of layers. With $$a=1$$ we obtain a standard quarter wave stack.  In order to suppress ripples in the low reflectance zone, we can apply apodization to the parameter $$a$$: $\left( T_H(i) H\;\; T_L(i)L\right)^n$ $T_H(i)=a \exp \left[-\left(i-N/2\right)^2/(2C^2)\right], T_L(i)=2-T_H(i)$ where $$C$$ is expressed from FWHM of the Gaussian function by:  $C=FWHM/\left[2\sqrt{2\ln 2}\right]$ Example: Reference wavelength $$\lambda_0=532$$ nm, spectral range of interest is from 400 nm to 700 nm, high reflectance zone is $$\lambda_0\pm 8$$ nm.  Layer refractive indices are 2.14 and 1.49, refractive index of the substrate and incidence medium are equal to 1.52 (immersed case) Reflectance of one of the solutions obtained with the help of formula constrained optimization:
 In OptiLayer this structure can be specified and optimized with respect to three parameters: $$a, \;C$$ and $$n=N/2$$. The structure can be specified in the two step dialog: Parameter $$a$$ can be varied in the range from 0.1 to 2, parameters $$C$$ is from 1 to 100, number of layer pairs $$n$$ is from 1 to 100.

### Easy to start

OptiLayer provides user-friendly interface and a variety of examples allowing even a beginner to effectively start to design and characterize optical coatings.        Read more...

### Docs / Support

Comprehensive manual in PDF format and e-mail support help you at each step of your work with OptiLayer.