Continuous Diode Laser Research Articles

Wavelength-influenced electrical performance of laser-written flexible copper-based structures

The one-step direct laser writing process has been an efficient strategy for constructing flexible metal structures. However, the effect of laser wavelength on the structuring process remains unclear, thus restricting the universal manufacturing process development. In this work, the feasibility of one-step writing of flexible Cu structures with different wavelength continuous diode lasers has been verified. Here, photothermal reactions dominate in the decomposition of the reducing agent to form copper structures. Differences in the wavelength primarily affect the photothermal reaction amplitude for structuring, resulting in a variation in the formation of Cu structures. Under our processing conditions, the photothermal reaction induced by 532 nm laser is higher than 808 nm laser, a higher reduced-joining degree of the Cu structure can be achieved by 532 nm laser. This results in a superior conductivity, adhesion, and bendability of Cu structures fabricated by 532 nm laser than that of 808 nm laser. Furthermore, strain sensors that can detect different bending angles and bending frequencies have been fabricated by 532 nm laser-written structures to demonstrate their practical applications.

Study of structural and magnetic properties of laser-irradiated zinc ferrite material

Crystalline ZnFe2O4 (zinc ferrite) material was prepared using the sol–gel technique and converted in the forms of 3 pellets, out of which 2 pellets were irradiated at room temperature by pulsed Nd:YAG laser with 1.5 W, λ = 532 nm named ZF1 and continuous AlGaAs diode laser of 4 W, λ = 808 nm called ZF2, respectively, while the 3rd pellet was kept as control and named ZF. Synchrotron X-ray Diffraction (S-XRD) reveals the marginal variation in the structure having the lattice parameters of 8.4364 Å for ZF, 8.4176 Å for ZF1 and 8.4187 Å for ZF2. The porosity after laser irradiation has been increased to 10.87% for ZF1 and 10.84%, for ZF2 from 10.28% for ZF. The blocking temperature (TB) has been ∼15 K for all samples. There had been a slight variation in the magnetization of irradiated pellets at 5 and 300 K compared to ZF. The separation between ZFC and FC curves, the measure of interaction between Fe ions has increased for irradiated pellets when compared with the separation for ZF. Moreover, magnetization (M) versus applied magnetic field (H) at 5 K in the range of ±1 T shows the ferrimagnetic behaviour and this ordering has been seen up to TB as visible from M-T curves, whereas the material becomes superparamagnetic above TB as observed from M-T & M-H measurements.

Effectiveness of laser pulsed irradiation for antimicrobial photodynamic therapy

The aim of this study was to compare two types of light irradiation devices for antimicrobial photodynamic therapy (aPDT). A 660-nm light-emitting diode (LED) and a 665-nm laser diode (LD) were used for light irradiation, and 0.1 mg/L TONS 504, a cationic chlorin derivative, was used as the photosensitizer. We evaluated the light attenuation along the vertical and horizontal directions, temperature rise following light irradiation, and aPDT efficacy against Staphylococcus aureus under different conditions: TONS 504 only, light irradiation only, and TONS 504 with either LED (30 J/cm2) or LD light irradiation (continuous: 30 J/cm2; pulsed: 20 J/cm2 at 2/3 duty cycle, 10 J/cm2 at 1/3 duty cycle). Both LED and LD light intensities were inversely proportional to the square of the vertical distance from the irradiated area. Along the horizontal distance from the nadir of the light source, the LED light intensity attenuated according to the cosine quadrature law, while the LD light intensity did not attenuate within the measurable range. Following light irradiation, the temperature rise increased as the TONS 504 concentration increased in the order of pulsed LD < continuous LD < LED irradiation. aPDT with light irradiation only or TONS 504 only had no antimicrobial effect, while aPDT with TONS 504 under continuous or pulsed LD light irradiation provided approximately 3 log reduction at 30 J/cm2 and 20 J/cm2 and approximately 2 log reduction at 10 J/cm2. TONS 504-aPDT under pulsed LD light irradiation provided anti-microbial effect without significant temperature rise.

Microstructural and Mechanical Characterization of Large Surfaces after Laser Cladding by Wavering of Nickel Coating on Cast-Iron Molds Used in Glass Industry

Laser cladding of a Ni based powder on cast iron is performed by a 4kW continuous diode laser. For this, a robot programming method named “Wavering” is used. Indeed, this method allows to cover large surfaces (width higher than 5 mm and thickness higher than 4 mm). The cast iron substrate used during this work is employed for its thermal properties in glass mold Industry. However, it has drawbacks which are weak wear, corrosion, and abrasion resistance. Conventional techniques used to protect the molds, like Plasma Transferred Arc (PTA), affect the molds microstructure, but also the thermal and mechanical properties. The laser cladding of the Ni based alloy allows to protect the molds without affecting the cast iron thermal properties (low Heat Affected Zone). The purpose of this research is to produce a well bonded Ni based melted powder without pores or cracks on large and curvilinear surfaces. First, the coating, adapted to this substrate geometry, is optimized. Then, an investigation of the impact of the processing parameters (power, scanning speed and wavering frequency) on the microstructure is carried out. Besides, the mechanical behaviour is analysed by microhardness. In addition, the evolution of the Heat Affected Zone (HAZ) according to the processing parameters is observed. Two kinds of areas are inspected in terms of microstructure: a stable area obtained after a single pass and an interferenced area linked to superimposed passes. Those analyses led to a cladding parameter optimization to obtain perfect bonding, to avoid porosity propagation and to limit the HAZ emergence on curvilinear surfaces. Finally, in comparison with the PTA technique, it appears that laser cladding process with wavering method leads to a good coating of curvilinear surfaces.

Laser irradiation effects on the dielectric properties of zinc ferrite at room temperature

Zinc ferrite (ZF) nanomaterials were synthesised by the sol–gel auto-combustion method. Synchrotron-XRD confirms the formation of the pure F-d3m spinel structure whereas EDX reveals the composition of synthesised nano ZF. We investigated and compared the dielectric properties of un-irradiated pellet ZF-UI and irradiated pellets ZF-I1 (pulsed Nd:YAG laser dose of 1.2 W, λ = 1064 nm), ZF-I2 (pulsed Nd:YAG laser dose of 1.5 W, λ = 532 nm) and ZF-I3 (continuous AlGaAs diode laser of 4 W, λ = 808 nm) at room temperature. Dielectric constant (ε′) decreased prominently for ZF-UI while it decreased gradually for ZF-I1 and its decrement for ZF-I2 and ZF-I3 is very slow whereas dielectric constant (ε ″) decreased prominently for ZF-UI and ZF-I1while reduced slowly for ZF-I2 and ZF-I3 in the low-frequency region. ε′ becomes ∼69% for ZF-I1 and ∼9% for ZF-I2 and ZF-I3 at a higher frequency of 2 MHz whereas ε ″ for radiated samples becomes steady and nearly equitable at higher frequencies in comparison to that of ZF-UI in the measured frequency range of 10 kHz to 2 MHz. Dielectric loss (tan δ) of all irradiated samples has decreased and become ∼33% for ZF-I3, 43% for ZF-I2, nearly equal for ZF-I1 at 104 Hz and then decreased continuously up to 2 MHz when compared to tan δ for ZF-UI. The Jonscher power law has been fitted in measured ac conductivity (σ ac) with angular frequency (ω) graphs. DC conductivity (σ dc), temperature-dependent parameter B(T) and frequency exponent (n) have been extracted. σ dc for all irradiated samples has decreased and become nearly 51% for ZF-I1, 3% for ZF-I2 and 2% for ZF-I3 in comparison to that of ZF-UI whereas B(T) increased to 1.6 times for ZF-I3 and decreased to 0.7 times for ZF-I1 and 0.2 times for ZF-I2 while n shows slight decrement for ZF-I2 and ZF-I3. Interpretation from Cole–Cole plots for un-irradiated and irradiated pellets is in agreement with our investigations. These results suggest that the dielectric properties of ZF can be controlled and tuned by laser irradiation.

Efficacy of Diode Laser 940 nm in Dentine Hypersensitivity Reduction: A Clinical Trial

Background: Dentin hypersensitivity is a discomfort arising from unprotected dentin as a response to heat, cold, touch, or pressure stimuli. Various treatment modalities, including laser light, have been used to manage such a problem. This study aims to evaluate the efficacy of diode laser 940 nm, with different powers in managing dentin hypersensitivity. Materials and Methods: A cross-sectional study was conducted from 1 January–5 April 2023 on a cohort of patients presented to the dental department clinics of our college with dentine hyper-sensitivity. A 10-second continuous mode diode laser light 940 nm at two different powers was used to evaluate its desensitizing effect for managing dentin hypersensitivity for six patients with a total number of teeth treated, 38 teeth. A jet of air/water was applied for a specific period and a certain distance from the tooth surface. Scores were documented for evaluating responses using the VAS scale. Results: A statistically significant decrease in dentine hypersensitivity was found immediately after one treatment session and after a 14-day follow-up period. Conclusions: It was established that using a diode laser (940 nm) successfully resolved instant and longstanding dentin hypersensitivity pain.

Tunable Diode Lasers for Analytics and Diagnostics

Continuous-wave diode lasers (DLs) with tunable emission wavelengths have become extensively used in various fields of analytical spectroscopy and diagnostics. Working in the near and mid-IR spectral region, tunable diode lasers are particularly effective in detecting simple molecules, making them invaluable for environmental monitoring, industrial process control, and diagnostics of subsonic and supersonic gas flows. However, the lack of commercial diode lasers operating in the spectral region shorter than 400 nm has restricted their applicability to elemental analysis, as many resonance lines of free atoms of elements lie in the region 250–400 nm. This review aims to highlight various applications of continuous diode lasers, which are lesser-known to analytical chemists. We briefly overview their main characteristics and discuss their advantages, enabling their successful implementation in traditional analytical spectroscopy tasks, as well as for diagnosing parameters of remote gas objects, including combustion processes in mixing gas flows.

Tunable Diode Lasers for Analytics and Diagnostics

Continuous-wave diode lasers (DLs) with tunable emission wavelengths have become extensively used in various fields of analytical spectroscopy and diagnostics. Working in the near and mid-IR spectral region, tunable diode lasers are particularly effective in detecting simple molecules, making them invaluable for environmental monitoring, industrial process control, and diagnostics of subsonic and supersonic gas flows. However, the lack of commercial diode lasers operating in the spectral region shorter than 400 nm has restricted their applicability to elemental analysis, as many resonance lines of free atoms of elements lie in the region 250–400 nm. This review aims to highlight various applications of continuous diode lasers, which are lesser-known to analytical chemists. We briefly overview their main characteristics and discuss their advantages, enabling their successful implementation in traditional analytical spectroscopy tasks, as well as for diagnosing parameters of remote gas objects, including combustion processes in mixing gas flows.

Terahertz Quasi-Time Domain Spectroscopy using a 808nm multimode diode laser

We report on a terahertz quasi-time domain spectroscopy (QTDS) system based on a low-cost continuous wave multimode diode laser. Commercially available low-temperature grown gallium arsenide (LT-GaAs) based photoconductive antennas (PCAs) with spiral and dipole configurations were used as emitter and detector, respectively. Terahertz pulses spaced at approximately 55 ps with a bandwidth of 400 GHz were obtained. Parametric measurements of the terahertz peak-to-peak intensity were performed by varying the injection current and temperature while maintaining incident laser power. The highest peak-to-peak intensity was obtained at 170mA injection current and 20° C temperature settings. The change in the THz peak-to-peak intensity is attributed to the mode hopping characteristics of the device which in turn, is dependent on injection current and temperature.

Angiogenetic and anti-inflammatory effects of photobiomodulation on bone regeneration in rat: A histopathological, immunohistochemical, and molecular analysis.

Post-surgical bone defects require new alternative approaches for a better healing process. For this matter, photobiomodulation therapy (PBMT) has been used in order to improve the process of healing, pain, and inflammation reduction and tissue rejuvenation. This study is set to evaluate the effect of PBMT on angiogenic and inflammatory factors for bone regeneration in rat post-surgical cranial defects. Thirty male Wistar rats were distributed accidentally into two groups (Subdivided into 3 groups according to their follow-up durations). During operation, an 8-mm critical-sized calvarial defect was made in each rat. A continuous diode laser was used (power density 100mW/cm2, wavelength 810nm, the energy density of 4J/cm2). Bone samples were assessed histomorphometrically and histologically after hematoxylin and eosin (H&E) staining. ALP, PTGIR, OCN, and IL-1 levels were measured by RT-PCR. VEGF expression was studied by immunohistochemistry analysis. The level of IL-1 expression decreased significantly in the PBMT group compared to the control after 7days (p<0.05), while, the PTGIR level was improved significantly compared to the control group after 7days. Furthermore, levels of OCN and ALP improved after PBM use; however, the alterations were not statistically meaningful (p>0.05). Evaluation with IHC displayed a significant rise in VEGF expression after 3days in the PBMT group compared to the control (p>0.05). In this study's conditions, the results showed a meaningful alteration in osteogenic, inflammatory, and angiogenic mediators in post-surgical calvarial defect following PBMT. It appears that PBM can accelerate angiogenesis in the bone healing procedure which can be helpful in bone tissue engineering.

Simulating the process of steady-state thermoreflectance for measuring the thermal conductivity of materials

The measurement of thermal conductivity by the method of steady-state thermoreflectance is based on the effect of heating the sample by laser radiation. The power of reflected radiation from the sample is measured using an additional probe laser. The change in the reflection coefficient of the studied material due to the heating is proportional to the change of the sample temperature. The radiation power absorbed by the material acts as a volumetric heat source. The value of thermal conductivity is calculated according to the Fourier’s law of thermal conductivity. A steady-state thermoreflectance setup requires calibration, i.e., thermal conductivity measurement of reference samples. The value of the calibration coefficient, in turn, depends on the characteristics of the lasers used in the setup. In this work, a numerical model of sample heating is proposed which allows considering the shape and diameter of the incident radiation beam, the distribution of radiation power over the beam area, and the absorption and reflection coefficients of the material. A methodology for samples reflection and absorption coefficients determination, including measurements and calculations considering the Fabry-Perot effect, is proposed. The study was performed for the samples of germanium, silicon, gallium arsenide, and sitall. The irradiation was performed with a continuous wave single-mode diode laser with a wavelength of 980 nm. The incident radiation power distribution over the beam area was approximated according to the Gaussian function in the OriginPro software. The radiation power that passed through the samples and reflected from them was measured. The temperature of the samples during irradiation was measured with a thermal imager. The reflection and absorption coefficients of the samples were determined from the results of radiation power measurements using a mathematical model of the interaction of plane-polarized TE electromagnetic radiation with the material. Comparison of the calculation results with the literature data for germanium, silicon, and sitall samples showed their correspondence. For gallium arsenide there was a discrepancy between the calculation results and the literature data. For gallium arsenide samples, a model considering the Fabry-Perot effect was used, and the optical properties were determined numerically by searching for the minimum modules of the transfer functions of the transmitted and reflected radiation in the Matlab program. The model of electromagnetic heating of the investigated samples was implemented in the COMSOL Multiphysics software. A method for the determination of the reflection and absorption coefficients of materials investigated by the steady-state thermorflectance is proposed. The proposed model allows considering beam shape, width and distribution of the radiation power as well as the value of the absorbed radiation power for each sample. The difference between the calculated values of the sample temperature and the measurement results does not exceed 9 %. The model can be applied to measure the thermal conductivity of bulk and thin-film materials with unknown properties.

Pre-heating of an aluminum sample using a continuous laser diode in LIBS experiments

We present here the study of the pre-heating of an aluminum sample in laser-induced plasma spectroscopy (LIBS) experiments. The pre-heating of the sample was made using a continuous-wave (CW) laser diode having a wavelength of 450nm and 3.8 W power. The laser diode is focused on the aluminum sample by means of a plane-convex lens with a focal length of 10 cm. The ablation plasma is created by a pulsed Nd:YAG laser with 7ns of pulse duration. The results of using different energy values per pulse of the ablation laser on the pre-heated sample are reported. The pre-heating of the aluminum sample, using this laser diode, shows an increment of 30-50% in the ionic line intensity.

Effect of continuous ultrasonic irrigation and diode laser activation on apical extrusion of debris: in vitro study

Effect of continuous ultrasonic irrigation and diode laser activation on apical extrusion of debris: in vitro study

Lasers for benign prostatic hyperplasia (hybrid, blue diode, TFL, Moses). Which one to choose?

To present the evidence of latest developments of lasers for the surgical treatment of benign prostatic hyperplasia (BPH). We focused on recent advancements in Ho:YAG laser such as Moses technology, the Thulium Fiber Laser (TFL), the blue diode laser, and hybrid laser. Laser enucleation of prostate techniques using either Ho:YAG laser with the Moses technology and Moses 2.0, or TFL seem efficient and safe compared with the standard enucleation using Ho:YAG laser. Only in vitro studies evaluated the blue diode laser and hybrid laser (combination of a continuous wave TFL and blue diode laser). Blue diode laser showed intermediate incision depth and minimal coagulation depth compared with Ho:YAG laser and Super Pulse TFL. Hybrid laser showed deep incision depth and small coagulation area compared with Ho:YAG laser and continuous wave TFL. Surgical treatment of BPH using Moses technology, Moses 2.0, and TFL shows encouraging results comparable to the standard enucleation using Ho:YAG laser. Only in vitro data are currently available for blue diode laser and hybrid laser. Future well-designed studies comparing these technologies and evaluating them on specific risk groups of patients as well as the long-term durability of outcomes are needed.

Effect of Ultrasonic and Diode Laser Irrigation Activation on Post-operative Pain and Microbial Reduction in Single Visit Endodontic Treatment of Necrotic Mandibular Molars

Aim: To clinically evaluate the effect of continuous ultrasonic and diode laser 810 wave length irrigation activation techniques on postoperative pain and bacterial reduction in single visit endodontic treatment of mandibular molars.&#x0D; Material and methods: Forty patients requiring root canal treatment therapy for necrotic mandibular molars teeth were included in this study with age ranges between 20 and 45 years. In all cases, single visit endodontic treatment was carried out using Revo-S rotary file system in crown down sequence. NaOCl 2.5% irrigation solution was used during treatment. Patients were randomly and equally assigned into two groups according to irrigation technique. Group (1): conventional syringe irrigation and group (2): continuous ultrasonic irrigation. Each group was subdivided into two sub groups (n = 10); subgroup 1A (conventional syringe irrigation with no laser), subgroup 1B (conventional syringe irrigation with diode laser), subgroup 2A (continuous ultrasonic irrigation with no laser) and subgroup 2B (continuous ultrasonic irrigation with diode laser).&#x0D; Postoperative pain evaluation was done using Visual Analogue Scale (VAS) at 6, 12, 24, 36, 48 hours and 7 days postoperatively. Microbiological detection of bacterial reduction was done by taking Samples (S1 and S2) for bacterial cultures. S1 after finishing access cavity and before mechanical preparation and S2 after finishing mechanical preparation and irrigation activation and before obturation. Samples were cultured on blood agar and determined as colony forming units (CFU/mL). Microbiological bacterial reduction was calculated accordingly. Statistical analyses were analyzed using the Mann-Whitney U test. The significance level was set at p &lt; 0.05.&#x0D; Results: In all sub groups, postoperative pain decreased by time in all time intervals but pain was significantly lower in subgroup (2B) (continuous ultrasonic irrigation with diode laser) than subgroup (1A) (conventional syringe irrigation with no laser) in all time interval. Microbiological results showed the highest bacterial reduction was in subgroup (2B) (continuous ultrasonic irrigation with diode laser) and least bacterial reduction was in subgroup (1A) (conventional syringe irrigation with no laser).&#x0D; Conclusion: Using diode laser and continuous ultrasonic irrigation activation techniques as adjunctive methods showed improvement in postoperative pain records and enhanced bacterial reduction in root canal therapy.&#x0D; Keywords: Continuous ultrasonic irrigation, diode laser 810, post-operative pain, bacterial reduction, single visit endodontic treatment.

Designing an optical frequency comb generator for visible light communication applications

&lt;p&gt;The optical frequency comb generator (OFCG) is an efficient optoelectronic device that is included in many important applications over a various field such as microwave and optical communication. A novel scheme of OFCG presented in this work for visible light communication application based on amplitude modulation, radio frequency (RF) signal, phase shift and two Mach-Zehnder modulators (MZMs), our design features are simple with more efficient power and premium flatness of comb lines, the number of generating frequencies lines was 64 with a power stronger than -2 dBm over a 340 GHz bandwidth from a single continuous laser diode. Different chirping factor (α) of MZMs are implemented (3, 5, 7), as the results the best results related to α=5 with extra flatness, the system was designed and simulated by VPI design suite 9.8.&lt;/p&gt;

Physical, Chemical, and Mechanical Evaluation of Irradiated Xeno-Sheep Bony Implantation by Low-Level Laser Therapy of Long Bones Fractures in Rabbits.

Bone grafts/implantation is widely used in veterinary medicine. The present study aimed to evaluate the physical, chemical, and mechanical prosperities of irradiated xeno-sheepbony implantation(X-SBI) by low-level laser therapy (LLLT) implanted in the induced empty defect of the femoral bones in rabbits. A total of 10 adult rabbits were used to create a 1cm length of the femoral gab surgically; thereafter, the empty space was filled with X-SBI and internally fixed by intramedullary pinning with two femoral fragments. The operated rabbits were assigned to the un-irradiated control group 1 which was left without laser irradiation, and irradiated group (group 2) which was irradiated on a daily basis by a continuous diode laser, a single dose at four points at the lateral aspect of the X-SBI for 5 min at a period of 72 intervals for 14th days post-operation with a dosage of 850 nm, 148.4 J/cm2. The parameters which were used for the evaluation of results after 3rd-month post-operation were physical, chemical, and mechanical examinations. The physical examination revealed high bone density and hardness at the sites of X-SBI of the irradiated group, as compared to the un-irradiated animals. Moreover, the chemical analysis demonstrated an increment in the level of bone calcium and phosphorus elements, as well as a decrease in the level of magnesium, potassium, and sodium in the irradiated group, as compared to the un-irradiated group. The mechanical and fracture tolerance results demonstrated a gradually high resistance level of fracture tolerance of irradiated animals, as compared to un-irradiated rabbits. It can be concluded that the irradiated X-SBI by LLLT could be used strongly and successfully to fill the empty space in the femoral bone, supporting body weight better and faster than the control group, with no complications or body rejection.

Transscleral cyclophotocoagulation with MicroPulse® laser versus cyclophotocoagulation with continuous diode laser in patients with open-angle glaucoma.

To present the efficacy and safety of surgical treatment of moderate to advanced stage of open-angle glaucoma using the surgical method of transscleral cyclophotocoagulation with MicroPulse® laser (Iridex, Silicon Valley, California, USA) and to compare these results with those of continuous transscleral cyclophotocoagulation with diode laser. In a prospective observational clinical study 22 patients (30 eyes) with moderate and advanced open-angle glaucoma underwent transscleral cyclophotocoagulation. 15 eyes were treated with transscleral cyclophotocoagulation with MicroPulse® laser with 2500 mW (group A) and 15 eyes with continuous diode laser 810nm and power between 2000 and 2300 mW (group B). The follow-up period of the study was 12months. A reduction of the intraocular pressure > 30% was achieved in 53.3% of the group A and in 60% of the group B during the follow-up period of 12months. A statistically significant decrease of the number of antiglaucoma agents was observed in group A. One eye (6.6%) of group A underwent additional antiglaucoma procedures to achieve target intraocular pressure. The corresponding percentage is 40% in group B. The postoperative inflammatory response was significantly more limited in group A compared to group B. The transscleral cyclophotocoagulation with MicroPulse® diode laser with 2500 mW achieves a similar decrease of the intraocular pressure as cyclophotocoagulation with continuous diode laser for the first postoperative months, but more satisfactory reduction of the number of eye drops as well as more limited postoperative inflammatory response.

Measurements of Metastable Molecules in Nonequilibrium Supersonic Flows

Nonintrusive laser diagnostics are used for the measurements of metastable nitrogen molecules in the lowest excited electronic state, , in a nonequilibrium flow, blowdown supersonic wind tunnel. The tunnel is operated with nitrogen at plenum pressures of Torr, with the flow expanding through a two-dimensional contoured nozzle to the Mach number of . The steady-state run time of the tunnel is approximately 10 s. The flow is excited by a repetitive nanosecond pulse discharge operated in the plenum or in the nozzle throat. Time-resolved absolute populations in the plenum are measured by single-pass, continuous wave tunable diode laser absorption spectroscopy (TDLAS). In the supersonic test section, absolute populations are measured by cavity ring down spectroscopy (CRDS), using a tunable pulsed laser system operated at 10 Hz. During each run, 50 single-shot ring down traces are acquired, demonstrating good shot-to-shot reproducibility. The results demonstrate that the cavity ring down time is not affected by the supersonic flow. populations and the flow temperature are inferred from the single-shot CRDS data. At the conditions when the flow is excited by the discharge in the nozzle throat, population in the supersonic test section is measured by both CRDS and TDLAS diagnostics. The two diagnostic techniques are complementary and can be used for characterization of nonequilibrium reacting flows over a wide range of pressures, including short-run-time high-enthalpy flow facilities.

High-efficiency ultra-compact near-infrared supercontinuum generated in an ultrashort cavity configuration.

We report a novel method to generate near-infrared supercontinuum (SC) in an ultrashort cavity configuration with only 11.5 m. With the continuous laser diode pump, a near-infrared SC with 26.8 W average output power and a spectrum ranging from 900 nm to 2000nm is demonstrated, and the laser diode pump to supercontinuum conversion efficiency is up to 60%. The spectral and power characteristics of the generated SC under different lengths of germanium-doped fiber (GDF) were carefully studied. This near-infrared SC generation method has the advantages of simple structure, low cost and good stability and also possesses the shortest fiber laser cavity length ever reported to the best of our knowledge.