There are many types of nonlinear optical techniques ( coherent raman spectroscopy, stimulated raman spectroscopy), and several depend on the spatial and temporal overlap of multiple optical pulses at different wavelengths on the target. Nonlinear spectroscopy results when a light field perturbs the optical properties of a molecule so that the subsequent light fields see changes in the molecular states. It is important that the different light fields interact with the molecular states over time periods that are shorter than periods associated with dephasing and population relaxation so that the effects of the first interaction are not lost. By exciting a state with one light field and probing it at a later time, nonlinear experiments allow one to investigate how quantum states evolve in time and how different states are related to each other.
Nonlinear molecular spectroscopy ( including CARS and SRS) is a versatile tool in pharmaceutics and biopharmaceutics, with a wide field of applications ranging from characterization of drug formulations to elucidation of kinetic processes in drug delivery. It could also provide fast detection and identification of counterfeit medicines. Since many blister package materials provide suitable spectral windows for both exciting and scattering radiations.
New developments in applications of nonlinear spectroscopy for studying drug delivery systems, in particular topical drug delivery have been reviewed. Well-established standard methods coupled with Raman spectroscopy enables to study drug release in semisolid formulations, drug penetration, and influence of penetration modifiers. This approach is also applicable for in vivo studies and in characterizing the structure of colloidal drug carrier systems. The interaction of therapeutic drugs and their target biomolecules is of great interest in pharmaceutical research.
In the pharmaceutical and chemical industry, one of the main challenges is to control the composition of the product. Quality testing for tablet composition and uniformity are excessively critical issues at manufacturing stage in pharmaceutical industries because composition and uniformity are the main concerns. A non-destructive and cost-effective analysis by Raman technique plays an important role for increasing the quality of products. Thus, Raman spectroscopy reduces time to analyse active ingredient composition of tablets while increasing the number of tablets tested with increased confidence level. The crystal forms present in the drug products can also be identified. Nonlinear Raman spectroscopy supports as a reliable tool in various industrial applications for monitoring and controlling solid elaboration processes.
CARS uses two synchronized picosecond sources to stimulate a strong signal response at the Anti-Stokes frequency. This happens when the wavelengths of the two lasers are separated by a wavenumber matching the Raman transition of the sample. Ti:Sapphire (Ti:S) lasers and OPOs are used nowadays for CARS experiments as they match the application requirements. However, the drawback is their size and the complexity to maintain the two lasers synchronized.
Genia photonics brings fiber laser based solutions to improve the process quality control. We propose a novel compact solution that allows fast and precise measurement techniques to achieve in-situ, standoff or remote detection and sensing. Genia Photonics’ synchronized programmable laser system uses its two laser outputs to generate CARS and SRS signals corresponding to the targeted wavenumbers. Since this compact laser system operates in the picosecond regime, the nonresonant background is eliminated allowing the acquisition of the information to be done very rapidly.