International Journal of Material Science Innovations (IJMSI) 2(6): 178-192, 2014 ISSN 2289-4063 © Academic Research Online Publisher Research Article Optical Properties and FWHM of Methylene Blue Doped Poly Vinyl Alcohol Films Mahasin F. Hadi AL-Kadhemy * &Ammar N. Abed AL-Jabry AL-Mustansiriyah Univ. –College of science- physics Dept.- Baghdad- IRAQ * Corresponding author. Tel.: +964 07702732705 E-mail address:drmahasinf@yahoo.com A b s t r a c t Keywords: Optical Properties, Polymers, PVA, Optical materials, Organic compounds, Methylene Blue. In this research the optical properties for pure PVA and PVA-Methylene blue (MB) films in different doping ratio that prepared by using casting method was been studied. The absorption and transmission spectra were measured by UV- Visible spectrophotometer. The optical energy gap was indirect transition for pure PVA film about 5.15eV for allowed and 5.17eV for forbidden. These energies were decreased with increasing doping ratio of MB contents to become 4.88eV and 4.85eV for allowed and forbidden, respectively. Whereas energy gap for Methylene blue in chloroform solution was 1.78 eV and 1.88 eV for allowed and forbidden indirect transition, respectively. The value of energy gap became 1.75 eV and 1.78 eV for allowed and forbidden indirect transition after doping with PVA polymer films for all doping ratio of dye solution. Full width half maximum absorption spectrum was calculated for all samples. Also, all optical constants (absorption coefficient, refractive index, extinction coefficient, and complex dielectric constants) were investigated and compared with other researches. Accepted:30September2014 © Academic Research Online Publisher. All rights reserved. 1. Introduction Methylene Blue is a heterocyclic aromatic chemical compound that has physical form green powder soluble in water, ethanol, ethylene glycol, methyl cello solve. It has many applications in biology, industry, chemistry and medical as inks, bone marrow, eye lens, skin diseases [1]. Figure 1-a shows the chemical structure of methylene blue. Poly vinyl alcohol is a polymer with carbon chain back bone with hydroxyl groups attached to methane carbons, these OH-groups can be a source of