We present a detailed overview of stimulated Brillouin scattering (SBS) in
 single-mode optical fibers. The review is divided into two parts. In the first part,
 we discuss the fundamentals of SBS. A particular emphasis is given to analytical
 calculation of the backreflected power and SBS threshold (SBST) in optical fibers
 with various index profiles. For this, we consider acousto-optic interaction in the
 guiding geometry and derive the modal overlap integral, which describes the
 dependence of the Brillouin gain on the refractive index profile of the optical
 fiber. We analyze Stokes backreflected power initiated by thermal phonons, compare
 values of the SBST calculated from different approximations, and discuss the SBST
 dependence on the fiber length. We also review an analytical approach to calculate
 the gain of Brillouin fiber amplifiers (BFAs) in the regime of pump depletion. In the
 high-gain regime, fiber loss is a nonnegligible effect and needs to be accounted for
 along with the pump depletion. We provide an accurate analytic expression for the BFA
 gain and show results of experimental validation. Finally, we review methods to
 suppress SBS including index-controlled acoustic guiding or segmented fiber links.
 The second part of the review deals with recent advances in fiber-optic applications
 where SBS is a relevant effect. In particular, we discuss the impact of SBS on the
 radio-over-fiber technology, enhancement of the SBS efficiency in Raman-pumped
 fibers, slow light due to SBS and SBS-based optical delay lines, Brillouin
 fiber-optic sensors, and SBS mitigation in high-power fiber lasers, as well as SBS in
 multimode and microstructured fibers. A detailed derivation of evolutional equations
 in the guided wave geometry as well as key physical relations are given in
 appendices.

Stimulated Brillouin scattering in optical fibers

Replacement of CH4 in the hydrate by use of liquid CO2

An overview is presented of experimental and theoretical research in the field of physics and engineering of singlet delta oxygen (SDO) production in low-temperature plasma of various electric discharges. Attention is paid mainly to the SDO production with SDO yield adequate for the development of an electric discharge oxygen–iodine laser (DOIL). The review comprises a historical sketch describing the main experimental results on SDO physics in low-temperature plasma obtained since the first detection of SDO in electric discharge in the 1950s and the first attempt to launch a DOIL in the 1970s up to the mid-1980s when several research groups started their activity aimed at DOIL development, stimulated by success in the development of a chemical oxygen–iodine laser (COIL). A detailed analysis of theoretical and experimental research on SDO production in electric discharge from the mid-1980s to the present, when the first DOIL has been launched, is given. Different kinetic models of oxygen low-temperature plasma are compared with the model developed by the authors. The latter comprises electron kinetics based on the accompanying solution of the electron Boltzmann equation, plasma chemistry including reactions of excited molecules and numerous ion–molecular reactions, thermal energy balance and electric circuit equation. The experimental part of the overview is focused on the experimental methods of SDO detection including experiments on the measurements of the Einstein coefficient for SDO transition and experimental procedures of SDO production in self-sustained and non-self-sustained discharges and analysis of different plasma-chemical processes occurring in oxygen low-temperature plasma which brings limitation to the maximum SDO yield and to the lifetime of the SDO in an electric discharge and its afterglow. Quite recently obtained results on gain and output characteristics of DOIL and some projects aimed at the development of high-power DOIL are discussed.

https://iopscience.iop.org/article/10.1088/0022-3727/40/2/R01/pdf

Physics and engineering of singlet delta oxygen production in low-temperature plasma

This paper presents a comprehensive list of Carbon Capture and Utilization technologies and applications, ranging from lab-scale R&D activities reported in academic papers to commercially establish...

Carbon capture and utilization technologies: a literature review and recent advances

Methane recovery from methane hydrate using pressurized CO2

We demonstrated the measurements of attenuation constant of a multi-mode fiber with 300-micron core diameter and 1-km length at 1070 nm. The observed attenuation constant was below 0.7 dB/km, the laser power of 5 kW was coupled into the 1-km fiber at 1070 nm, and the overall transmittance was 85%, and the first Raman Stokes signal was observed in the transmitted laser spectrum. We demonstrated concrete cutting with a 4-kW fiber laser at 1070 nm. The slab thickness was 100 mm. This technique can be extended to thick concrete slabs more than 1 m without increasing laser power.

Laser cutting for thick concrete by multi-pass technique

A set of coupled-wave equations for stimulated Brillouin scattering (SBS) in multimode optical fibers excited by single-mode laser light is derived. The analytical solution of the critical pump power is also derived. The solution explains the experimental results well.

https://iopscience.iop.org/article/10.1143/JJAP.40.3191/pdf

Critical Power of Stimulated Brillouin Scattering in Multimode Optical Fibers

An electro-optic (EO) deflector was used for Q-switching of a laser cavity with a Nd-doped yttrium vanadate (Nd:YVO(4)), enabling a short pulse width and a high peak power to be achieved at a high repetition rate of over 1 MHz. The EO deflector has a low optical loss during Q-switching without polarizers and can be used to form a short laser cavity. A repetition rate of 1.4 MHz with a pulse width of 39 ns was achieved. An output power of 2.7 W was obtained at a pump power of 6.5 W.

1.4-MHz repetition rate electro-optic Q-switched Nd:YVO4 laser

A new laser tool for the extraction of methane from methane hydrates is proposed, and its superiority over other methods is discussed The type of laser suitable for the extraction is also discussed, and the chemically pumped oxygen-iodine energy transfer laser (COIL) is found to be the most suitable candidate

https://iopscience.iop.org/article/10.1143/JJAP.42.5648/pdf

Extraction of Methane from Methane Hydrate Using Lasers

We report on a compact trace nitrogen dioxide (NO2) detector based on cavity ringdown spectroscopy (CRDS), using a passively locked external cavity diode laser (PLEC-DL) in the visible wavelength region. Tailoring the spatial mode matching conditions of an antireflection (AR)-coated diode laser with a high finesse external cavity for effective optical feedback into the DL allows for stable resonant enhancement in the external cavity without any electric feedback apparatus. The external cavity having a finesse in excess of 1.4×105 acts as a ringdown cavity with an effective optical volume (i.e., detection volume) of less than 1 cm3. We successfully demonstrated a noise equivalent absorption loss of 1.4×10-8 cm-1, corresponding to a detection limit of 40 ppb NO2 concentration with a very compact configuration. For differential absorption CRDS, we realized a dual wavelength-locked PLEC-DL in an external cavity simultaneously. Measurements of various NO2 concentrations in N2 based on differential absorption CRDS were performed.

https://iopscience.iop.org/article/10.1143/JJAP.47.6478/pdf

Simple Real Time Trace Nitrogen Dioxide Detector Based on Continuous-Wave Cavity Ringdown Spectroscopy Using Passively Locked External Cavity Diode Laser

Kazuyoku Tei

Papers

Laser cutting for thick concrete by multi-pass technique

Critical Power of Stimulated Brillouin Scattering in Multimode Optical Fibers

1.4-MHz repetition rate electro-optic Q-switched Nd:YVO4 laser

Extraction of Methane from Methane Hydrate Using Lasers

Simple Real Time Trace Nitrogen Dioxide Detector Based on Continuous-Wave Cavity Ringdown Spectroscopy Using Passively Locked External Cavity Diode Laser