Infrared Diode Laser Research Articles

Development of the laser-induced water bubble actuator

Aiming to realize the newly actuator without any electric cable, the use of laser-induced water vaper bubble has been proposed and performed the principle confirmation experiment. The laser induced water bubble has been applied for the liquid jet therapeutic catheter in medical field. The liquid jet system use physiologic saline for the liquid and a Ho: YAG laser of 2.1μm wavelength that has highly absorption of water. Instead of this combination, we propose the use of carbon powder suspension for working liquid and an infrared Laser Diode (LD) of 970nm wavelength. As the 970nm LD light is not absorbed by water but carbon, the water of the working liquid could be vaporized by heated carbon. LD is considered as a suitable laser source for the actuator in the viewpoint of output controllability by the drive-current modulation. Figure 1 shows the conceptual image of the laser-induced water bubble actuator. It is constructed with a 970nm LD, an optical fiber and an actuator unit with working liquid for producing bubble. An optical fiber connector (SMA connector) has been used for the bubble generator unit in our principle confirmation experiment. We use the inlet space for inserting and fixing fiber cable as the actuator cylinder. The working liquid was prepared by suspending carbon powder of 20μm particle size in water with surface active agent. After the working liquid has been injected in the cylinder, a stainless steel rod of Φ2.3mm diameter and 30mm length inserted as the actuator piston. When the laser irradiation was performed at the LD power of 160-180W and the pulse duration of 2msec, the reciprocating motions of the stainless steel rod have been observed. For the next step, we are planning to evaluate the operating characteristic and also try to maximize the generating force. This work was supported by JSPS KAKENHI Grant Number JP16K12914.

Thin-layer chromatography combined with diode laser thermal vaporization inductively coupled plasma mass spectrometry for the determination of selenomethionine and selenocysteine in algae and yeast

In this work we present a simple and cost-effective approach for the determination of selenium species in algae and yeast biomass, based on a combination of thin-layer chromatography (TLC) with diode laser thermal vaporization inductively coupled plasma mass spectrometry (DLTV ICP MS). Extraction of freeze-dried biomass was performed in 4M methanesulphonic acid and the selenium species were vaporized from cellulose TLC plates employing a continuous-wave infrared diode laser with power up to 4 W using a simple laboratory-built apparatus. Selenomethionine and selenocysteine were quantified with limits of detection 3 μg L−1 in a Se-enriched microalgae Chlorella vulgaris and yeast certified reference material SELM-1. Results delivered by TLC-DLTV ICP MS were consistent with those obtained by a routine coupling of high-performance liquid chromatography (HPLC) to ICP MS. In addition, the TLC approach is capable of analyzing extract containing even undiluted crude hydrolysates that could damage HPLC columns.

Development and validation of a diode laser sensor for gas-phase CO2 monitoring above champagne and sparkling wines

Champagne and sparkling wines are multicomponent hydroalcoholic systems supersaturated with dissolved carbon dioxide (CO2). Under standard tasting conditions, CO2 progressively invades the headspace above glasses, thus progressively modifying the chemical headspace perceived by the consumer. Monitoring in situ, and as accurately as possible the level of gas-phase CO2 above liquid is therefore a challenge of importance aimed at better understanding the close relationship between the release of gas-phase CO2 and a collection of various parameters such as glass-shape, and champagne temperature, for example. The development and validation of an instrument which combines two infrared diode lasers coupled with an optical fiber and devoted to real-time monitoring of gas-phase CO2 above sparkling beverages are reported. A first set of data showing the impact of liquid phase temperature on the release of gas-phase CO2 found in the headspace of champagne glasses is presented.

Photothermally controlled 50 mA gating in VO2-based planar device using NIR laser diode

By utilizing a near infrared laser diode as an excitation light source, we demonstrated a photothermally controlled current gating of 50 mA in a two-terminal planar device based on a vanadium dioxide (VO2) thin film grown by a pulsed laser deposition method. The photothermally controlled on/off triggering of the device current was accomplished by controlling the output power of the laser beam that illuminated the VO2 film. The transient responses of photothermally triggered currents were analyzed when periodical laser pulses from the laser diode stimulated the VO2 device at a variety of pulse widths and repetition rates. A switching contrast between off-state and on-state currents was evaluated as ∼11905, and average rising and falling times were measured as ∼45 and ∼19 ms, respectively.

Measurement of Water Vapor Concentration in Narrow Channel of PEFC Using Fiber-Optic Sensor Based on Laser Absorption Spectroscopy

To achieve high performance and long-term operation of polymer electrolyte fuel cell (PEFC), it is essential to understand and control water transports in operating fuel cell. In the previous studies, water distributions along flow channels were investigated using micro gas chromatograph (mGC) [1-2]. Although GC method enables to analyze water vapor concentration with high accuracy, it takes a long time (at least two minutes) to collect a gas sample and identify a species. On the other hand, several researchers have applied tunable diode laser absorption spectroscopy (TDLAS) technique to gas analysis in PEFCs [3-4]. TDLAS is one of the high-sensitive absorption spectroscopy techniques which measure the absorbance of a species and identify its concentration using infrared diode laser. Since laser beam is directly injected into gas channel of PEFC, in-situ monitoring of water vapor concentration can be performed on operational fuel cells with a high time resolution of millisecond. The authors have now developed a fiber-optic gas sensor based on TDLAS to apply it to the measurement of water vapor concentration in flow channels of working PEFCs. The introduction of small-size fiber-optic sensors enables in-situ laser diagnostics within millimeter-scale narrow channels. In this study, a transmission/reception integrated fiber-optic probe is newly developed to detect absorption spectra of water in gas channels of PEFCs. This novel probe is compactly composed of one light-projecting fiber and six receiving fibers, which are coaxially arranged. Since multiple output signals detected by using six photodiodes are synthesized, the optical fringe noise in them can be effectively canceled. Even if the fringe noise tends to be generated inside narrow channels, the high-resolution absorption spectra with better S/N ratio can be obtained by the signal synthesizing. Furthermore, the TDLAS system with the above-mentioned fiber-optic probe is constructed as shown in Fig. 1, and the concentration measurement of water vapor was tentatively attempted using a simulated flow cell. In this system, the triangular-wave laser beam modulated at the high frequency of 10 kHz is emitted from a DFB laser diode (wavelength: 1392 nm) and injected into the straight gas flow channel (30 mm length, 1.5 mm width, 1.5 mm depth) of the simulated cell through the fiber-optic probe. Some reflected lights from the gas channel are detected at six photodiodes and converted to the electric signals. Subsequently, the synthesized output signal is transmitted to a lock-in amplifier and the high-sensitive harmonic spectra are obtained by phase-sensitive detection. The method to quantify the water vapor concentration in the channel from the measured spectrum data is also proposed. The simulated flow cell is fabricated by stainless steel plates. The humidified oxygen is fed into the gas channel at the flow rate of 200 mL/min. Fig. 2 presents the second-harmonic (2f) spectra of water obtained from the TDLAS measurement in the simulated flow cell at 70 deg. C. The mole fraction of water vapor is changed from 0.3 to 25.7%. The vertical axis shows the intensity of 2f signal, and the horizontal axis shows the wavelength. At the low water concentration of 0.3-8.9 mol%, the peak-valley height of 2f absorption spectrum increases with an increase in water concentration. On the other hand, when the concentration of water vapor is higher than 14.3 mol%, the peak-valley height of 2f signal gradually decreases with increasing water mole fraction. Since the relationship between the water mole fraction and the peak-valley height of 2f spectrum is not monotonous, the water concentration cannot be quantitatively estimated only by the 2f spectrum data. The authors propose the improved method for the accurate and effective quantification of water vapor concentration with the use of 2f and 4f absorption spectra. As a result of the spectral analysis, it was found that the peak-valley ratio of 2f and 4f spectra exponentially increases with water mole fraction. The water vapor concentration can be estimated from the 2f/4f peak-valley ratio. In addition, it was revealed that the measurement accuracy of water vapor mole fraction is less than 0.5% at 70 deg. C. These results suggest that the fiber-optic TDLAS sensor has the ability to accurately monitor in-situ water transports within narrow channels of actual fuel cells.

Degradation Mechanisms of Heterogeneous III-V/Silicon 1.55- $\mu \text{m}$ DBR Laser Diodes

This paper reports an extensive analysis of the degradation processes of heterogeneous III-V/Silicon infrared laser diodes designed for integrated telecommunications and interconnects. By submitting the devices to a series of constant current stress tests, a gradual degradation of the main device parameters was observed. In particular, in every stress scenario the devices under test showed: 1) an increase in the threshold current; 2) a decrease of the turn-ON voltage; and 3) an increase in the apparent carrier concentration within the space charge region. The variation of the electrical parameters (turn-ON voltage and apparent charge concentration) was found to be significantly correlated to the optical degradation for long stress times; the results support the hypothesis that degradation originates from an increase in the non-radiative recombination rate, possibly due to the diffusion of defects toward the active region of the devices. In order to investigate the physical origin of those defects, a capacitance deep level transient spectroscopy analysis was performed. The results indicate the presence of five different deep levels, with a main trap located around 0.43 eV above the valence band energy. This trap is compatible with an interface defect located between the In 0.53 Al x Ga 0.47-x As separate confinement heterostructure region and the InP layer.

Blue diode laser versus traditional infrared diode laser and quantic molecular resonance scalpel: clinical and histological findings after excisional biopsy of benign oral lesions

This study aims to compare the use of the innovative blue diode laser (BLUE group) with two traditional surgical techniques: the infrared diode laser (IR group) and the quantic molecular resonance scalpel (QMR group) in the excision of benign oral lesions. Ninety-three patients underwent surgical excision of a benign oral lesion and were followed up for 30 days for pain (0 to 10 visual analogue scale), bleeding, and painkillers’ assumption (yes/no). A blind pathologist evaluated the thermal damage along the cutting margin. Although referred pain was lowest in the BLUE group from day 7 on (p<0.05), all patients referred minimum discomfort after surgery. The BLUE group reported minimum bleeding and necessity of sutures (p<0.000). The QMR group showed the highest bleeding during surgery (p<0.000), while after 14 and 30 days no patient bled. Most of the patients in all groups did not need painkillers. The lowest thermal damage (p<0.000) was found in the BLUE group (71.3±51.8???m), whereas the IR group proved the highest (186.8±82.7???m) compared both with the BLUE and QMR (111.4±55.4???m) groups. All the techniques allowed correct histological sampling. All the experimented techniques offer interesting advantages, although the blue laser minimizes risk of bleeding with limited thermal damage.

Photothermal therapy of melanoma tumor using multiwalled carbon nanotubes.

Photothermal therapy (PTT) is a therapeutic method in which photon energy is transformed into heat rapidly via different operations to extirpate cancer. Nanoparticles, such as carbon nanotubes (CNTs) have exceptional optical absorbance in visible and near infrared spectra. Therefore, they could be a good converter to induce hyperthermia in PTT technique. In our study, for improving the dispersibility of multiwalled CNTs in water, the CNTs were oxidized (O-CNTs) and then polyethylene glycol (PEG) was used for wrapping the surface of nanotubes. The formation of a thin layer of PEG around the nanotubes was confirmed through Fourier transform infrared, thermogravimetric analysis, and field emission scanning electron microscopy techniques. Results of thermogravimetric analysis showed that the amount of PEG component in the O-CNT-PEG was approximately 80% (w/w). Cell cytotoxicity study showed that O-CNT was less cytotoxic than pristine multiwalled nanotubes, and O-CNT-PEG had the lowest toxicity against HeLa and HepG2 cell lines. The effect of O-CNT-PEG in reduction of melanoma tumor size after PTT was evaluated. Cancerous mice were exposed to a continuous-wave near infrared laser diode (λ=808 nm, P=2 W and I=8 W/cm2) for 10 minutes once in the period of the treatment. The average size of tumor in mice receiving O-CNT-PEG decreased sharply in comparison with those that received laser therapy alone. Results of animal studies indicate that O-CNT-PEG is a powerful candidate for eradicating solid tumors in PTT technique.

Hybrid 3-D-Printing Technology for Tunable THz Applications

In recent years, additive manufacturing has experienced rapid growth, due to its inherent capabilities for creating arbitrary 3-D structures, accessibility, and associated low manufacturing costs. This paper first reviews the state of the art in 3-D printing for terahertz (THz) applications and identifies the critical features required for such applications. The future potential for this technology is demonstrated experimentally with the first 3-D-printed, optically controlled THz IQ vector modulator. Here, miniature high-resistivity silicon implants are integrated into metal-pipe rectangular waveguides. The 3-D-printed split-block assembly also houses two packaged infrared laser diodes and a heat sink. The measured performance of a proof-of-principle 4-quaternary amplitude modulation (4-QAM) vector modulator that operates up to 500 GHz is reported. This new hybrid 3-D printing THz technology, which combines semiconductor devices with potentially low-cost, high-performance passive guided-wave structures represents a paradigm shift and may prove to be an ideal solution for implementing affordable transceivers in future ubiquitous THz applications.

(162) Pre-surgical intraplantar resiniferatoxin decreases post-operative pain in rats with plantar incision

Post-operative pain is a major cause of morbidity and suffering. Central sensitization during surgical intervention has been implicated in the development of chronic pain this may, in part, be due to inadequate peri-operative and post-operative analgesia. Neurons expressing TRPV1 (transient receptor potential cation channel subfamily V) have been implicated in nociception in a variety of pain models. The present study investigated therapeutic and molecular aspects of perioperative ablation of TRPV1-containing peripheral nerve terminals with intraplantar RTX (resiniferatoxin) in a surgical incision pain model. Furthermore, as RTX has algesic actions before institution of analgesia, the effect of lidocaine administered before RTX on post-operative hyperalgesia was investigated. Sprague-Dawley rats were administered RTX and/or lidocaine in the perioperative window prior to intraplantar incision in a 2x2 factorial design. Evoked pain to mechanical and thermal stimulation was assessed, as was spontaneous pain with measurement of guarding and home cage monitoring. RNA was extracted from spinal cord dorsal horn on post-operative day 2 for transcriptomic analysis. Plantar incision caused thermal hyperalgesia, but intraplantar RTX attenuated responses to noxious infrared diode laser thermal A-delta or C-fiber stimulation during the 4 days of the study (p<0.05). Mechanical allodynia, measured by Von Frey stimulation, was pronounced over the first 2 post-operative days, and was also attenuated by pre-emptive RTX. Guarding of the wound was most pronounced at 4 hours and 24 hours pre-emptive RTX attenuated this measure of spontaneous pain (assessed by guarding score, p<0.05). Mechanical pain sensation, measured by pinprick, was preserved after RTX treatment, as was motoric function (measured by time spent on rotarod). Lidocaine pre-treatment had no effect on any of the behavioral assays. Transcriptomic analysis for differential gene expression was also undertaken. Peri-operative administration of RTX, delivered in a clinically relevant manner, was efficacious in decreasing post-operative pain.

Lasers in the treatment of acne.

Acne is a chronic disease of the pilosebaceous units, presenting as inflammatory or noninflammatory lesions, affecting primarily the face but also the back and chest. The mainstay of treatment remains topical retinoids, benzoyl peroxide, azelaic acid, antibiotics, and isotretinoin, many of which result in poor compliance, lack of durable remission, and incur adverse effects. The use of lasers to treat acne is continuously increasing because of their minimal complications, limited number of office-based treatments required, potential benefits of simultaneously treating acne scarring, and the rapid onset of results. The 1450 nm diode laser, 585- and 595-nm pulsed dye lasers (PDLs), near infrared diode lasers, 1320 nm Nd:YAG laser, 532 nm potassium titanyl phosphate laser, 1064 nm long-pulsed Nd:YAG laser, 1540 nm Erbium (Er):Glass Laser, and the 1550 nm Er:Glass fractional laser are among the most common lasers used to treat acne and acne scarring. These lasers target the underlying causes of acne including the colonization of Priopionibacterium acnes, high levels of sebum production, altered keratinization, inflammation, and bacterial colonization of hair follicles on the face, neck, and back. We review the efficacy and side effect profiles of various lasers used to treat acne.

Infrared spectroscopy of 2ν4 and ν3 + 2ν4 bands of the NO3 radical

The 2ν4 band spectrum of 14NO3 observed with infrared diode laser spectroscopy was analyzed with the Fourier transform (FT) spectrum in the 760cm−1 region, including the Coriolis interaction between v4=2 and v2=1. The vibrational frequencies of v4=2, l=0, and l=±2 have been determined to be 752.4033(86) and 771.7941(81)cm−1, respectively. By considering the anharmonic interaction among the 2ν4, ν3, ν4, ν2, and ν2+3ν4 states, a relation among the cubic anharmonic constants was obtained as 0.452 Φ444ζ2,4−0.271 Φ344ζ2,3=127.7cm−1. The ratio of transition moments μ(ν2)/μ(2ν4) was determined to be 0.3 from the perturbation analysis. The second strongest infrared band of 14NO3, ν3+2ν4, observed around 1927cm−1has been analyzed with the hot band ν3+2ν4−ν4 by including the Coriolis interaction with the v2=1, v4=3 state. Similarly, the same band of 15NO3 was analyzed to give the band origin of 1897.9325(6)cm−1. The isotope shift 28.2cm−1 for the ν3+2ν4 vibrational frequency is consistent with a predicted value of 27.3cm−1. Although there are two A′ states in v3=1, v4=2, only one A2′ state has been assigned in the hot band, indicating that the other band has weak intensity. This fact and the strong intensity of the ν3+2ν4 band (l3=±1, l4=0) are understood as the effect of vibronic interaction. The first-order Coriolis coupling constant ζ of ν3+2ν4, l3=1, l4=0 is similar to those of the ν4 and ν3+ν4 states, and it is concluded that the vibrational Coriolis coupling constant is nearly zero and the observed constants of ζ=−0.19 (14NO3) and ζ=−0.15 (15NO3) also originate from the effect of vibronic interaction.

Real-time imaging of methane gas leaks using a single-pixel camera.

We demonstrate a camera which can image methane gas at video rates, using only a single-pixel detector and structured illumination. The light source is an infrared laser diode operating at 1.651μm tuned to an absorption line of methane gas. The light is structured using an addressable micromirror array to pattern the laser output with a sequence of Hadamard masks. The resulting backscattered light is recorded using a single-pixel InGaAs detector which provides a measure of the correlation between the projected patterns and the gas distribution in the scene. Knowledge of this correlation and the patterns allows an image to be reconstructed of the gas in the scene. For the application of locating gas leaks the frame rate of the camera is of primary importance, which in this case is inversely proportional to the square of the linear resolution. Here we demonstrate gas imaging at ~25 fps while using 256 mask patterns (corresponding to an image resolution of 16×16). To aid the task of locating the source of the gas emission, we overlay an upsampled and smoothed image of the low-resolution gas image onto a high-resolution color image of the scene, recorded using a standard CMOS camera. We demonstrate for an illumination of only 5mW across the field-of-view imaging of a methane gas leak of ~0.2 litres/minute from a distance of ~1 metre.

Electronic structure and optical properties of dilute boron-bismide quaternary alloys BxGa1–xAs1–yBiy/GaAs for infrared optoelectronic devices

Electronic structure and optical properties of the dilute boron-bismide quaternary BxGa1−xAs1−yBiy alloys have been investigated from first-principles. The calculated structural parameters are found to be in excellent agreement with the experimental data. Optical properties are calculated by the recent developed Tran–Blaha-modified Becke–Johnson (TB-mBJ) potential which gives accurate band gaps. We find that incorporation of B and Bi into GaAs resulted in a reduced band gap. A quaternary BxGa1−xAs1−yBiy alloy with x=y=0.125 is predicted to be lattice-matched to GaAs. The optical properties of BxGa1−xAs1−yBiy depend on the incorporated of B and Bi contents. This makes BxGa1−xAs1−yBiy/GaAs a promising system for the design of high-efficiency solar cells and advanced infrared Laser Diodes.

Laser induced white lighting of graphene foam

Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources.

Determination of QW laser diode degradation based on the emission spectrum

The possibility of laser diodes degradation control by monitoring of their spectrum is shown. For red and infra-red laser diodes, the time dependence of the radiation spectrum width was obtained.

Investigation and Demonstration of a WR-4.3 Optically Controlled Waveguide Attenuator

We report the design and demonstration of a compact WR-4.3 (170–260 GHz, equivalent to WR-4 band in Electronics Industries Alliance band designation) optically controlled waveguide attenuator using an E-plane tapered high-resistivity micromachined silicon absorber. Variable attenuation is realized by illuminating the silicon absorber with different light intensities from a fiber-guided infrared laser diode. Finite element method simulation has shown that high attenuator performance can be potentially achieved. For a prototype demonstration, a WR-4.3 optically controlled attenuator has been designed and implemented using an E-plane split waveguide configuration. The attenuator has been characterized in the WR-4.3 waveguide band using a vector network analyzer and the results show that a 0.6-dB insertion loss, greater than 10-dB return loss, and an average of approximately 25-dB tuning range have been achieved over most of the WR-4.3 band (i.e., 170–230 GHz). This approach is promising for developing high-performance variable waveguide attenuators into the millimeter-wave and terahertz regime.

Comparison between Er:YAG laser and bipolar radiofrequency combined with infrared diode laser for the treatment of acne scars: Differential expression of fibrogenetic biomolecules may be associated with differences in efficacy between ablative and non‐ablative laser treatment

Fractional Er:YAG minimizes the risk associated with skin ablation. Infrared diode laser and radiofrequency have suggested comparable improvements in acne scar. We compared the clinical efficacy of Er:YAG laser and bipolar radiofrequency combined with diode laser (BRDL) for the treatment of acne scars. Moreover, acute molecular changes of cytokine profile associated with wound healing have been evaluated to suggest mechanisms of improvement of acne scar. Twenty-four subjects with mild-to-moderate acne scars were treated in a split-face manner with Er:YAG and BRDL, with two treatment sessions, 4 weeks apart. Objective and subjective assessments were done at baseline, 1, 3, 7 days after each treatment and 4 weeks after last treatment. Skin biopsy specimens were obtained at baseline, 1, 3, 7, 28 days after one session of treatment for investigation of molecular profile of acute skin changes by laser treatment. Investigator's Global Assessment representing the improvement degree shows 2.1 (50%) in fractional Er:YAG and 1.2 (25%) in BRDL. Er:YAG induced the later and higher peak expression of TGFβs and collagenases, whereas BRDL induced earlier and lower expression of TGFβ and collagenases, relatively. PPARγ dropped rapidly after a peak in Er:YAG-treated side, which is associated with tissue inhibitor of metalloproteinase (TIMP) expression. We observed higher expression of TIMP after Er:YAG treatment compared with BRDL by immunohistochemistry, which may be associated with the expression of upregulation of collagen fibers. The superior efficacy of Er:YAG to BRDL in the treatment of acne scars may be associated with higher expression of collagen which is associated with differential expression of TGFβs, collagenases, PPARγ, and TIMP. Lasers Surg. Med. 49:341-347, 2017. © 2016 Wiley Periodicals, Inc.

Photobiomodulation by Infrared Diode Laser: Effects on Intracellular Calcium Concentration and Nitric Oxide Production of Paramecium.

In Paramecium, cilia beating is correlated to intracellular calcium concentration ([Ca2+ ]i) and nitric oxide (NO) synthesis. Recent findings affirm that photobiomodulation (PBM) can transiently increase the [Ca2+ ]i in mammalian cells. In this study, we investigated the effect of both 808 and 980 nm diode laser irradiated with flat-top hand-piece on [Ca2+ ]i and NO production of Paramecium primaurelia, to provide basic information for the development of new therapeutic approaches. In the experiments, the laser power in CW varied (0.1; 0.5; 1; and 1.5 W) to generate the following respective fluences: 6.4; 32; 64; and 96 J cm-2 . The 6.4 J cm-2 did not induce PBM if irradiated by both 808 and 980 nm diode laser. Conversely, the 32 J cm-2 fluence had no effect on Paramecium cells if irradiated by the 808 nm laser, while if irradiated by the 980 nm laser induced increment in swimming speed (suggesting an effect on the [Ca2+ ]i, NO production, similar to the 64 J cm-2 with the 808 nm wavelength). The more evident discordance occurred with the 96 J cm-2 fluence, which had the more efficient effect on PBM among the parameters if irradiated with the 808 nm laser and killed the Paramecium cells if irradiated by the 980 nm laser. Lastly, the 980 nm and 64 or 96 J cm-2 were the only parameters to induce a release of stored calcium.

MOVPE growth and characterization of quaternary Ga(PAsBi)/GaAs alloys for optoelectronic applications

Dilute bismide Ga(PAsBi)-based structures are promising candidates for highly efficient optoelectronic applications, like the 1eV sub-cell in multi-junction solar cells or the active region in infra-red laser diodes. The band gap can be tuned independently from the lattice constant, which theoretically enables the deposition of lattice-matched layers in a wide range of band gap energies on GaAs substrate. In this work, firstly, the shifts in the band edge positions as a function of composition that are possible with the Ga(PAs(Bi)) alloy were estimated using the virtual crystal approximation and valence band anti-crossing theory. Secondly, systematic investigations on MOVPE growth of Ga(PAsBi) layers are presented. Finally, we show the first photoluminescence activity of quaternary Ga(PAsBi) and compare the experimental results to theory.