Modeling Thin Film Multilayer Broad-Band-Pass Filters in Visible Spectrum

Wide bandpass optical filters with TiO2 and Ta2O5

“…These ripples can be suppressed using layer matching with incident medium and substrate. Such technique has been found very successful as a de- sign technique to reduce ripples in the passband, as reported earlier in one of our publications [6], but requires additional one or two materials to carry out the desired task in practice. This makes the deposition process more complicated, with material matching an additional consideration.…”

“…This problem could be resolved by proper matching of the top and bottom layers of the configuration with incident medium and substrate respectively. The layer adjacent to the incident medium is required to be adjusted in thickness and refractive index to acquire a proper matching for ripple reduction [6]. This introduces additional material or materials in the design.…”

“…There are, in addition, a small selection of other methods which could give bandpass characteristics. One of them is given below [6]:…”

Modeling and preparation of practical optical filters

“…We proposed a model of a bandpass filter in our previous work which involved comprehensive modeling exercise to come up with a very high quality bandpass optical filter in visible spectrum [5]. The modeled structure was based on the following configuration: incident medium (air)/[2HL] n /substrate (glass).…”

“…Ripples forming at the two extremes of the pass band for quarter-wave thick layers were controlled by using matching layers at the incident medium and substrate side of the stack. Initially, zinc sulfide (H) and cryolite (L) were used as the fundamental materials in the main body of the stack but later on ZnSe was also used in the main body to get a proper matching of the main stack with outer matching layers [5]. Finally, 21 layer structure ( Fig.…”