# Optics and spectroscopy. Laser physics

## The Influence of Hydrogen Bond on the Structure and IR Spectrum of Triphenyl Phosphite

**Background and Objectives: **The IR spectra of triphenyl phosphite (TPP) have been measured at temperatures of 12 and 320 K in five phase states: crystalline (monoclinic and hexagonal phases), “glacial”, amorphous and liquid. It is necessary to clarify the effect of hydrogen bonding on the structure and IR spectrum of TPP. **Materials and Methods:** The IR spectra were measured on the IFS-88 spectrophotometer using the OPUS software. The spectral resolution was 2 cm^(-1).

## Optical Characteristics of Asymmetrical Hyperbolic Metamaterials

**Background and Objectives: **Metamaterials, which are artificial structures with specified properties, keep the interest to nest investigations and creation of new types of them due to their unusual properties. One of the promising variant of the metamaterials is hyperbolic metamaterials (HMM) which exhibit the hyperbolic-type dispersion in the space of wave-vectors and are described by the diagonal extremely anisotropic permittivity tensor.

## Interpretation of IR and Raman Spectra of Albumin

**Object and purpose of work: **The subject of the study is bovine serum albumin (BSA). The aim of the work is to give an interpretation of the vibrational spectra of BSA aqueous solution in the region of ~1700–600 cm– 1. **Methods: **In this regard the experimental measurement of the IR and Raman spectra of BSA and the calculation of vibrational spectra of zwitterionic ion forms 20 amino acids and their dipeptides were carried out. The effect of anharmonicity and intermolecular interaction (IMI) on the vibrational spectra of amino acids was considered.

## Difference-Frequency Generator and Optical Parametric Oscillator Pumped by a Semiconductor Disk Laser: Comparative Study with a Time Delay Model

**Background and Objectives:** High-resolution spectroscopy is known to need sources of coherent radiation in the mid- and farinfrared spectral bands. Sources based on optical nonlinear interaction (a difference-frequency generator and an optical parametric oscillator) are known to be almost ideally suitable for an application. Intracavity realizations of the devices with a nonlinear crystal located in the cavity, can likely be made simple, compact and easy to use.

## A Hybrid Approach in Modeling of Statistical Characteristics of Multiple Scattered Light

**Background and Objectives:** A hybrid approach to modeling of the statistical characteristics of multiple scattered light in application to optical probes of random media is considered. The approach is based on recovery of the probability density of path lengths for partial components of a scattered light field in a probed medium using approximate analytical methods or the numerical simulation.

## Methods of Autodyne Interferometry of the Distance by Injected Current Modulation of a Semiconductor Laser

**Background and Objectives: **Two methods of distance interferometry for two types of wave modulation of laser radiation have been presented. The methods of triangular and harmonic wave modulation of a signal have been described. The advantages of the triangular wave modulation method in combination with the use of the frequency of the self-mixing signal spectrum, as well as the advantages of the harmonic wave modulation method in combination with the use of the amplitudes of the self-mixing signal spectrum have been shown.

## Intermolecular Interaction in Two-component Compounds of Nanodiamonds and Doxorubicin

**Background and Objectives:** Detonation nanodiamond (ND) is one of the most promising materials for targeted drug delivery – one of rapidly developing areas of modern chemistry, pharmacology and medicine. Wide possibilities of surface modification and advantageous dimensions make nanodiamonds very attractive objects for using in the drug delivery process. A number of studies have shown that therapeutic efficacy of drugs is enhanced and their toxicities may be attenuated with immobilization on the enriched ND. There are a lot of drug immobilization methods on ND surfacy.

## Optical Absorption and Raman Scattering in Doped Crystals TlGaSe2 and TlInS2

**Background and Objectives. **The TlGaSe2 and TlInS2 monocrystals are the А3В3С6 2 type ternary semiconductor compounds. Studies of TlGaSe2 and TlInS2 materials are carried out quite intensively due to the uniqueness of their optical and electrophysical properties and significant prospects for their practical use. At the same time, information about the effect of specific doping impurities on the properties of such materials is insufficient and often contradictory.

## Discrete-Eigenvalue Multiplexing for Soliton Fiber-Optic Communication Links

**Background and Objectives:** The nonlinear Fourier transform gives a powerful tool to analyze fiber-optics solitons. The solitons are described by a discrete set of eigenvalues of two coupled differential equations, which gives the nonlinear Fourier transform. Using the discrete eigenvalues for optical signal coding can increase the signal-to-noise ratio and reduce the effect of fiber nonlinearity. In the present paper an all-fiber-optics method is proposed to modulate the discrete eigenvalues.

## Mathematical Modeling of Lihgt Transfer in Low-Coherence Reflectometry of Random Media

**Background and Objectives: **The mathematical model of stochastic interference of spectrally selected fluorescence radiation in multiple scattering random media is considered. The expressions for the normalized second- and third-order moments of spatial intensity fluctuations of detected probe light are derived.