Pulsed CO2 Research Articles

High-quality rapid fabrication method of a D-shaped optical fiber based on a CO2 laser

D-shaped fibers have attracted widespread attention due to their special structure and excellent performances. However, the fabrication of D-shaped fiber faces many challenges. Mechanical polishing and chemical etching are two traditional methods for D-shaped fiber fabrication, in which micro-crack or contamination is unavoidable. In this paper, we report an efficient method to produce D-shaped fiber with a pulsed CO2 laser. The effects of processing parameters on processing efficiency and surface quality are investigated experimentally, and the processing defects such as melting debris and oscillation are also studied. The optimized processing parameters are provided.

Mother's hand tool as a skin-to-skin contact simulation instrument decreases pain levels in newborns

BACKGROUNDSensory stimulation activates the gate control mechanism, raises the level of beta endorphins, and the secretion of beta endorphins increases the pain threshold, reducing or eliminating the feeling of pain. It has been reported that skin-to-skin contact or sensual stimulation reduces stress, pain and crying time in newborns. The present study aimed to examine the effect of the mother’s hand tool (MHT) - developed by the researchers for three purposes: touch, positioning and vibration - on pain levels in newborns. METHODSA quasi-experimental study was conducted involving 52 newborns aged 0-15 days who were being treated in the neonatal intensive care unit. The MHT was applied to support the newborn and was applied 8 times in 24 hours for 3 minutes in total. Demographic data collection form (DDCF), neonatal evaluation form (NEF) to assess the respiratory rate, pulse rate, SPO2 and CO2 level, and neonatal infant pain scale (NIPS) were used to collect data. The Wilcoxon signed rank test was applied to analyse the data. A p value of <0.05 was considered to be statistically significant. RESULTSAfter the MHT application, it was revealed that there was a significant difference in pulse rate (p=0.000), SPO2 level (p=0.029), CO2 level (p=0.000) and NIPS pain scores (hour 6,9,12,15,18, and 24) and total NIPS (p=0.000) pain scores, before and after MHT practice. CONCLUSIONThis study demonstrated that MHT application to the newborns had a decreasing effect on pain level, heart rate, CO2 level, and an increasing effect on SPO2 level.

Application of ultra pulse CO2 lattice laser in the treatment of female urinary incontinence.

BackgroundThis study aimed to explore the application of CO2 lattice laser in the treatment of mild and moderate urinary incontinence in female patients.MethodsWe analyzed the clinical data of 33 female patients with mild to moderate urinary incontinence from a prospective cohort study, who were treated with FemiLift CO2 lattice laser instrument (Alma Laser Ltd, Caesarea, Israel) at our hospital from January 2018 to December 2018. All the female patients were married and fertile, with a mean age of (43.15±6.49) years old (35–62 years old). There were 18 participants with mild urinary incontinence and 15 with moderate urinary incontinence. All participants received laser treatment 3 times, with an interval of 30 days. The International Consultation of Incontinence Questionnaire- Short Form (ICIQ-SF) survey was conducted before the treatment, 3 months after, and 6 months after the treatment. A 1-hour urine pad test was used to quantify the leakage of urine. Residual urine and urine routine examination were performed to exclude other combined diseases.ResultsAfter 3 times of treatment with FemiLift CO2 laser, 13 cases were cured in 3 months, and 16 cases were cured in 6 months. 10 cases and 15 cases were significantly improved in 3 or 6 months, respectively. 2 patients had no significant changes, and no adverse reactions were recorded. The pad test showed that the symptom of all 33 patients were significantly improved, and the average scores of ICIQ-SF were significantly decreased (P<0.05) from 12.36 (Grade I) and 15.67 (Grade II) (5-21) before treatment to 3.73(Grade I) and 5.49 (Grade II) (1-12) after 6 months of therapy.ConclusionsThe CO2 lattice laser is safe and effective in the treatment of mild and moderate urinary incontinences in female patients, which can effectively improve the symptom of urinary leakage without obvious adverse reactions.

Multi-objective Optimization of Kerf-taper and Surface-roughness Quality Characteristics for Cutting-operation On Coir and Carbon Fibre Reinforced Epoxy Hybrid Polymeric Composites During CO2-Pulsed Laser-cutting Using RSM

Current research focuses on optimizing various quality characteristics for kerf geometry generated through laser cutting of Coir fibre/carbon fibre/epoxy resin hybrid composite adjacent to straight cut profile employing pulsed CO2 laser system. The Kerf taper (KT) and the Surface roughness (SR) are the main quality parameters discussed. Dependent on significant process parameters, namely gas pressure, cutting speed, pulse frequency and pulse width predictive models were developed. In accordance with Taguchi's L9 orthogonal array (OA), the cutting trials are designed. Process-parametric optimization was performed using Response Surface Methodology (RSM). Furthermore, experiments were performed to obtain experimental data for the analysis of cut quality features. The impact of the input variables on the response characteristics is also explored. The morphological characterizations have been performed to analysis the effect of machining-variables and cut-quality for the top and bottom kerf widths with various laser cutting variables in the pulse laser-cutting of Coir-fibre/carbon-fibre/epoxy-resin hybrid composite. For SR and KT, the developed second order surface response model was found very successful. The optimal levels of cutting variables for KT are established at Gas pressure-6 N/mm2, pulse width-2.04 ms, cutting speed-8.01 mm/s, pulse frequency-15 Hz, for sample A1, Gas pressure-5.47 N/mm2, pulse width-2.5 ms, cutting speed-8.81 mm/s, pulse frequency-8.43 Hz, for sample A2, Gas pressure-3.85 N/mm2, pulse width-1.5 ms, cutting speed-9.06 mm/s, pulse frequency-5 Hz, for sample A3 additionally for SR Gas pressure-2 N/mm2, pulse width-1.5 ms, cutting speed-7 mm/s, pulse frequency-5 Hz, for sample A1, Gaspressure-2.36 N/mm2, pulse width-1.5 ms, cutting speed-7 mm/s, pulse frequency-15 Hz, for sample A2, Gaspressure-6 N/mm2, pulse width-1.5 ms, cutting speed-11 mm/s, pulse frequency-8.73 Hz, for sample A3. Regression results and linear and square impact of laser cutting variables have been revealed to be important to validate the model.

Selectivity Control of Cu Nanocrystals in a Gas-Fed Flow Cell through CO2 Pulsed Electroreduction.

In this study, we have taken advantage of a pulsed CO2 electroreduction reaction (CO2RR) approach to tune the product distribution at industrially relevant current densities in a gas-fed flow cell. We compared the CO2RR selectivity of Cu catalysts subjected to either potentiostatic conditions (fixed applied potential of −0.7 VRHE) or pulsed electrolysis conditions (1 s pulses at oxidative potentials ranging from Ean = 0.6 to 1.5 VRHE, followed by 1 s pulses at −0.7 VRHE) and identified the main parameters responsible for the enhanced product selectivity observed in the latter case. Herein, two distinct regimes were observed: (i) for Ean = 0.9 VRHE we obtained 10% enhanced C2 product selectivity (FEC2H4 = 43.6% and FEC2H5OH = 19.8%) in comparison to the potentiostatic CO2RR at −0.7 VRHE (FEC2H4 = 40.9% and FEC2H5OH = 11%), (ii) while for Ean = 1.2 VRHE, high CH4 selectivity (FECH4 = 48.3% vs 0.1% at constant −0.7 VRHE) was observed. Operando spectroscopy (XAS, SERS) and ex situ microscopy (SEM and TEM) measurements revealed that these differences in catalyst selectivity can be ascribed to structural modifications and local pH effects. The morphological reconstruction of the catalyst observed after pulsed electrolysis with Ean = 0.9 VRHE, including the presence of highly defective interfaces and grain boundaries, was found to play a key role in the enhancement of the C2 product formation. In turn, pulsed electrolysis with Ean = 1.2 VRHE caused the consumption of OH– species near the catalyst surface, leading to an OH-poor environment favorable for CH4 production.

Co-precipitation continuous synthesis of the Ni-Rh-Ce0.75Zr0.25O2-δ catalyst in the membrane dispersion microreactor system for n-dodecane steam reforming to hydrogen

Precipitation at the micro-scale to produce nanoparticles with small particle size and uniform dispersion is feasible. A membrane dispersion microreactor (MR) - matching spiral tube system was used to synthesize highly dispersed (MR)-Ni-Rh-Ce0.75Zr0.25O2-δ and (MR)-Ni- Ce0.75Zr0.25O2-δ catalysts with active metal particle sizes of 4.3 and 4.6 nm. Rapid nucleation of the catalyst precursor was achieved in the microreactor and ordered growth occurred in the spiral tube. Characterization by TEM, pulse CO chemisorption, and Raman spectroscopy prove that the catalysts synthesized in the microreactor system possess more oxygen vacancies and uniformly supported active metal than those in the stirred tank (S). The apparent activation energies of the catalysts for n-dodecane steam reforming (SR) increase in the following order: (MR)-Ni-Rh-CZO (62 kJ/mol) < (S)-Ni-Rh-CZO (67 kJ/mol) < (MR)-Ni- CZO (77 kJ/mol) < (S)-Ni-CZO (84 kJ/mol). The initial hydrogen yields of (MR)-Ni-Rh-CZO and (S)-Ni-Rh-CZO are 88 and 59%, respectively, at T = 650 °C, WHSV = 12 h−1, and S/C = 4. TPSR experiments indicated that (MR)-Ni-CZO mostly contributed to the cleavage of C–C and C–H bonds. The carbon deposition in the first 12 h of n-dodecane SR is only 2.4 mg/(g-cat·mol-H2). For optimizing the continuous synthesis method, the initial hydrogen yield can be further improved to above 95% by increasing the mixing intensity, decreasing the ratio of the dispersed to continuous phase, and increasing the spiral tube length to synthesize better-dispersed catalysts.

Periorbital Hyperpigmentation—Dark Circles under the Eyes; Treatment Suggestions and Combining Procedures

Periorbital hyperpigmentation (POH) is a frequent concern among both young and adult patients. The etiology is multifactorial with a genetic background. Prevalence is higher in darker skin types. It has been estimated as high as 30% in a recent Indian study. Females are often more disappointed by POH than males. Treatment has to consider underlying pathologies and patients’ needs. We present our treatment algorithm for POH. In this study, 74 patients with POH, 64 females (86.5%) and 10 males (13.3%), were treated. Of these, 39 patients (53%) had a family history of POH. The age range of patients was 18−57 years (average: 36.1 years). In case of tear trough deformity, soft tissue augmentation was used by injection of hyaluronic acid gel, calcium hydroxylapatite, or autologous fat. Blepharoplasty with partial fat pad resection or repositioning via arcus marginalis release was used to correct severe orbital fat herniation and excess of the lower lid skin. Melanin hyperpigmentation of the skin was improved by sessions of Q-switched 1064 and 532 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. Small vessels (capillaries and veins) were targeted by a 1064 nm long-pulsed Nd-YAG laser. Sessions of intense pulsed light (IPL) or CO2 fractional laser were employed to improve skin texture and fine lines. Topical hyaluronic acid-based formulations may be used as adjuvant self-treatment by patients. For pigmented and mixed-type POH, ultraviolet light protection is recommended as a maintenance treatment. By the use of various technologies, treatment can be individually tailored.

Investigation on laser beam figuring of fused silica using microsecond pulsed CO2 laser radiation

A laser-based process chain is a possible solution to increase precision and reduce production time in optics manufacturing of components with complex shaped surfaces. A new high-precision laser ablation process was investigated using CO2 laser radiation and microsecond laser pulses. An average ablation depth of approx. 0.1 nm per laser pulse indicates that material ablation on an atomic/molecular scale was achieved. Four characteristic laser processing regimes and their related dominant physical process mechanisms were identified. The effect of crucial process parameters such as pulse energy, pulse duration and fluence on ablation depth and spatial resolution was empirically investigated. Ablation depths smaller than 5 nm per layer and a spatial resolution of less than 50 μm were achieved in areal laser ablation. The potential use of this high-precision laser ablation process was studied for an iterative process cycle (laser beam figuring - LBF) consisting of contactless surface measurement and subsequent laser ablation. The feasibility of LBF for form correction of fused silica components was successfully demonstrated, while a reduction in average surface roughness from Sa = 10.3 nm to 3.5 nm was achieved. High stability in pulse energy is the key requirement for high precision in ablation depth.

Cu(I) Reducibility Controls Ethylene vs Ethanol Selectivity on (100)-Textured Copper during Pulsed CO2 Reduction.

The electrochemical CO2 reduction reaction (CO2RR) can convert widely available CO2 into value-added C2 products, such as ethylene and ethanol. However, low selectivity toward either compound limits the effectiveness of current CO2RR electrocatalysts. Here, we report the use of pulsed overpotentials to improve the ethylene selectivity to 67% with >75% overall C2 selectivity on (100)-textured polycrystalline Cu foil. The pulsed CO2RR can be made selective to either ethylene or ethanol by controlling the reaction temperature. We attribute the enhanced C2 selectivity to the improved CO dimerization kinetics on the active Cu surface on predominately (100)-textured Cu grains with the reduced hydrogen adsorption coverage during the pulsed CO2RR. The ethylene vs ethanol selectivity can be explained by the reducibility of the Cu(I) species during the cathodic potential cycle. Our work demonstrates a simple route to improve the ethylene vs ethanol selectivity and identifies Cu(I) as the species responsible for ethanol production.

Dynamic Boundary Layer Simulation of Pulsed CO2 Electrolysis on a Copper Catalyst

Author(s): Bui, JC; Kim, C; Weber, AZ; Bell, AT | Abstract: Pulsed electrolysis has been demonstrated to improve the faradaic efficiency (FE) to C2+ products during the electrochemical reduction of CO2 over a Cu catalyst, but the nature of this enhancement is poorly understood. Herein, we developed a time-dependent continuum model of pulsed CO2 electrolysis on Cu in 0.1 M CsHCO3 that faithfully represents the experimentally observed effects of pulsed electrolysis. This work shows that pulsing results in dynamic changes in the pH and CO2 concentration near the Cu surface, which lead to an enhanced C2+ FE as a consequence of repeatedly accessing a transient state of heightened pH and CO2 concentration at high cathodic overpotential. Using these insights, a variety of pulse shapes were explored to establish operating conditions that maximize the rate of C2+ product formation and minimize the rates of H2 and C1 product formation.

Enhanced conductivity of the Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) films using pulsed CO2 laser irradiation

In this study, a thermal treatment method for poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT: PSS) films on glass substrate was treated by a pulsed CO2 laser in the atmospheric environment. The two main parameters of the PEDOT: PSS films in thermal treatment are laser fluence and scan speed. The electrical, optical, and surface properties were measured by an in-line four-point probe instrument, spectrophotometry, atomic force microscope (AFM), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). After treatment, the conductivity was enhanced from 2.83E-02 S/cm to 59.4 S/cm in 181 s due to removing the residual water in the film. Furthermore, the transmittance value was decreased from 89.1% to 88.5%, and the surface roughness increased from 2.27 to 2.49 nm. The conductivity increased due to the reunion between PEDOT: PSS molecules and increased in the surface PEDOT/PSS ratio. However, when the laser power exceeded the durability of the PEDOT: PSS, a significant decrease in conductivity and transmittance was observed. Compared with the hotplate thermal treatment in the atmospheric environment, CO2 pulsed laser thermal treatment has advantages for PEDOT: PSS thermal treatment in a small region.

In silico design of a thermal atomic layer etch process of cobalt

Thermal atomic layer etch (ALE), facilitating the removal of up to one monolayer of material per cycle, is growing in importance for thin-film processing. The number of available ALE processes is much smaller than for atomic layer deposition, its complementary growth process. Quantum chemical simulations are a key approach in the development of new thermal ALE processes, however, methodologies and workflows need to be developed. In this regard, the present paper reports a simulation-based approach toward the development of new thermal ALE processes using metallic cobalt as a test case. We demonstrate a predictive process discovery approach for ALE in which target volatile etch products and the corresponding gas phase reactants are chosen from the literature, an overall ALE cycle for each combination of reactant is investigated for thermochemical favorability, and the detailed mechanisms of the individual reaction steps in the proposed ALE processes are studied using density functional theory. From these results, we derive a temperature-pressure process window for each combination of reactants at typical reactant and product pressures allowing the selection of an ALE process window. For Co ALE, we investigated propene, butyne, silane, and trimethyl silane as a first pulse reactant and CO as the second pulse reactant. We propose propene and CO as the best combination of reactants for Co ALE. Propene adsorbs with sufficient strength to the target Co atom at temperatures below the CO decomposition temperature of 440 K, which results in the lowest energy etch species. This approach is equally relevant for the ALE process design of elemental, binary, and ternary materials.

Numerical simulation and experimental study of pulsed CO2 laser-induced micro-channels on poly-ether sulfone (PES) polymer

TEA CO2 laser pulses were used to create micro-channels on PES samples with various low fluences and scanning speeds in 16–50 J/cm2 and 23–45 µm/s ranges, respectively. Different micro-channels were created with 142–342 µm widths and 85–440 µm depths which has been 3-dimensionally simulated using ABAQUS software based on the finite element method and CIN heat source. The sharp spike (~85 ns FWHM) and long tail (~3.8 µs) parts of the laser pulses were mathematically modeled with individual Gaussian profiles. A good agreement has been found between the simulated and experimental results. Namely, the maximum relative errors of the depth and opening width of the grooves remain below 11.5% and 12.3%, respectively. However, the corresponding mean values of these relative errors do not exceed 4.1% and 7.5%, respectively.

Parametric oscillation of acoustical phonon mode in magnetized doped III–V semiconductors

Using the hydrodynamic model of semiconductor plasmas and coupled mode theory of interacting waves, we develop a theoretical formulation followed by numerical analysis to study parametric oscillation of acoustical phonon mode in magnetized doped III–V semiconductors. The origin of nonlinear interaction is assumed to lie in effective second-order optical susceptibility ( $$\chi^{(2)}$$ ) arising due to nonlinear induced current density and acousto-optic polarization of the semiconductor medium. Expressions are obtained for threshold pump intensity ( $$I_{{0,{\text{th}}}}$$ ) and operational characteristics such as conversion efficiency ( $$\eta_{k}$$ ) and single pass signal power gain ( $$g_{{{\text{sp}}}}$$ ) of the proposed single resonant optical parametric oscillator. Numerical analysis is made for a representative n-InSb crystal irradiated by 10.6 µm pulsed CO2 laser. The effects of some important parameters including external magnetic field ( $$B_{0}$$ ), mirror reflectivity ( $$R$$ ), crystal length ( $$L$$ ), etc. on $$I_{{0,{\text{th}}}}$$ , $$\eta_{k}$$ and $$g_{{{\text{sp}}}}$$ of the single resonant optical parametric oscillator are analyzed in detail. The analysis establishes the technological potentiality of magnetized doped III–V semiconductors as the hosts for fabrication of highly efficient and widely tunable single-resonant optical parametric oscillators.

Experimental study on the rock erosion performance of a pulsed abrasive supercritical CO2 jet

An experimental study on the erosion behaviors of pulsed abrasive supercritical CO2 jets (PASJ) was performed using sandstone as the target specimen. The erosion depth, erosion area, and mass loss of the crater caused by PASJ were discussed in detail. The optimal configuration of the Helmholtz nozzle was first determined, and then influences of erosion-related working parameters including the jet pressure, abrasive particle size, ambient fluid and jet impingement angle on the rock erosion performance were analyzed with this nozzle. The results indicate that increasing jet pressure helps improve the erosion depth and area, which is mainly the result of increased jet kinetic energy. The erosion capability of PASJ is highly dependent on the size of abrasive particles. Coarser particles shows greater effectiveness in producing deeper erosion craters and the jets are more likely to retain rock-erosion ability as the standoff distance increases. At a given standoff distance, the crater eroded in air is deeper than those eroded in gaseous CO2 and in supercritical CO2, because the particles are slowed much more slowly in air under decreased drag. Moreover, the area of the crater eroded by PASJ in air is also largest due to the highest radial spreading rate. Finally, it was found that mass loss and erosion depth first increase and then decrease with the increase of jet impingement angle (θ) and the maximum values are reached at θ = 70°, whilst the erosion area increases monotonically with decreasing jet impingement angle.

The effect of assist gases on the quality of edge surfaces of Al-Li alloys cut with a pulsed Q-switched CO2 laser

The effect of assist gases (argon or air) on the quality of edge surfaces of aluminum alloys cut with a pulsed Q-switched CO2 laser was experimentally investigated. Sheets of both Al-Mg-Li and Al-Cu-Li alloys with thicknesses of 1.5 and 2.0 mm were cut. It was found that the morphologies of the cut-edge surfaces were significantly different after cutting with argon and air. For the first time, the cutting process was carried out using a laser-plasma mode, when an optical discharge was maintained in an argon flow. At an argon pressure of 0.5 bar, the cut-edge surfaces were without dross and their roughness were significantly lower than that after cutting with a continuous wave laser. Severance energy levels were similar for both laser-plasma and continuous wave cutting modes.

Characteristics of discharge and beyond extreme ultraviolet spectra of laser induced discharge gadolinium plasma

The gadolinium (Gd) plasma is a potential beyond-EUV (BEUV) source for the extension of extreme ultraviolet lithography at 13.5 nm. A laser induced discharge plasma (LDP) is an effective way to excite the target material into high temperature plasma. A pulsed CO2 laser ablates a Gd plate cathode and produces an initial plasma, triggers a discharge between a Gd plate cathode and a stainless-steel cone anode, the current produces high temperature discharge plasma and creates an environment for BEUV radiation. A RLC model is used to estimate the equivalent circuit resistance and inductance, the resistance is about 0.70–0.75 Ω and the inductance is about 2.3–2.4 μH. A grazing incident ultraviolet spectrometer is established to study the Gd plasma’s BEUV radiation. With the laser energy above 120 mJ and voltage above 6.7 kV, Gd plasma spectra near the 6.7 nm is obtained. It is found that the relative spectral intensity increases and the peak of emission moves to a shorter wavelength corresponding to a higher voltage and laser energy. An atomic code combined with a simplified collisional-radiative model is used to calculate the theoretical spectra and estimate the electron temperature and density range of the LDP plasma.

Detection of 9.5 μm CO2 laser pulses in indium doped PbTe p-n junction

A unique feature of the PbTe semiconductor is the growth of its forbidden energy gap with increasing temperature. This allows saving diode-typical characteristics at temperatures up to 180 K. PbTe p-n diodes were fabricated by means of indium donor diffusion into PbTe single crystals grown using the Czochralski technique. The dark saturation current density was ~10−5 A/cm2 at T = 100 K, whereas at T = 180 K it reached ~10−1 A/cm2. The photovoltage signals induced by a pulsed CO2 laser light across PbTe p-n junction were investigated over the 100–180 K temperature range. The two-photon absorption-caused photovoltaic effect is observed for the first time in In doped PbTe p-n junction for 9.5 μm wavelength at T = 100 K.

PHOTO-INDUCED EFFECTS FIRST ORDER IN CHALCOHENID SYSTEMS OF AG-GA(IN)-SI(GE)-S(SE)

To study the possibilities of the most efficient use of crystals in optoelectronic devices, we studied the change in the absorption coefficient depending on the energy of the incident electromagnetic wave (photoinduced absorption). It was found that photoinduced absorption changes were observed under the influence of a microsecond pulsed CO2 laser and a solid-state laser with a wavelength of 808 nm. When irradiated with 808 nm laser, the photoinduced changes are associated with pure electronic transitions, and when irradiated with CO2, these levels are excited due to the interaction of phonons. The similarity of the changes caused by the solid-state laser with a wavelength of 808 nm and the CO2 laser testifies to the fundamental role of the electron-phonon interaction. The study of changes in the absorption coefficient near the edge of the intrinsic absorption band when irradiated with a solid-state laser (808 nm) shows the absence of irreversible modifications. This allows the use of these materials for use as optically controlled materials for visible and infrared lasers.

Free and bound charge carriers dependent Raman susceptibilities in weakly-polar magnetoactive semiconductors

In this paper, an analytical investigation of free and bound charge carriers dependent Raman susceptibilities has been made in weakly-polar magnetoactive semiconductors. The coupled mode approach has been used to obtain expressions for real and imaginary parts of Raman susceptibilities. The semiconductor sample is assumed to be illuminated by an off-resonant pulsed laser under Voigt geometry. For numerical estimations, we choose n-type doped InSb crystal at liquid nitrogen temperature and illuminated by a pulsed CO2 laser at 10.6 μm wavelength. Efforts have been paid to optimize the doping concentration, external magnetic field and pump intensity to obtain enhanced values of Raman susceptibilities and change of their sign. The change of sign of enhanced Raman susceptibilities, in weakly-polar semiconductors under appropriate selection of n-type doping and external magnetic field, validates the possibility of selected sample as a potential candidate material for the fabrication of stimulated Raman scattering dependent widely tunable optoelectronic devices such as optical switches and frequency converters.