జర్నల్ ఆఫ్ లేజర్స్, ఆప్టిక్స్ & ఫోటోనిక్స్

In the case of gases weakly ionized with ultra-short pulses, the electrons that follow the laser field are neither bound nor free. This review paper presents a simple approach to calculate the electron index based on a known electron motion in a non-relativistic regime. This basic approach does not neglect the time varying index. This review is an effort to capture concepts of the transient electron index, like the electron index created in the laser filamentation.

Two-dimensional optical vortex beams can propagate stably and undergo bending in nonlocal media with the aid of a spatial soliton, the latter preventing their destabilization and breakup. By colaunching a suitable pair of collinear soliton and vortex beams in nematic liquid crystals, we conduct a series of numerical experiments to demonstrate that the vortex beam can be made to propagate in the nematicon waveguide and follow its trajectory, even in the cases of refraction and total internal reflection at a dielectric interface. Modulation theory supports these findings and provides an excellent theoretical framework.

The performance of semiconductor injection lasers is limited by optical feedback noise. The laser intensity noise is greatly increased even by small amount of optical feedback. Although superposition of high-frequency current on the injection current is popularly used to solve the problem, proper modulation frequency and depth must be  chosen empirically. In this paper, we numerically analyze this problem based on a set of multimode rate equations, modified to include OFB (optical feedback) and HFI (high frequency current). We concentrate only on low frequency type noise where intensity noise is maximum in the lower frequency region. The results show that the feedback noise was reduced when HFI released coupling effects and thereby suppressed mode hopping. The feedback noise was still remained high when the modulation frequency was coincided with a rational number of the round trip time period of optical feedback. A simple formula together with a tree is newly reported from experimental and numerical data to find the rational numbers at which the feedback noise remains high for a particular external cavity length.
Dependency of the rational numbers on external cavity lengths is also reported in this paper.

Background: Visible and near-IR energies have been shown to inhibit the growth of various microorganisms.
There may be clinical application for this inhibitory effect in the treatment of infected wounds particularly, and other infectious states generally.
Aim: The purpose of this study was to determine whether there was an interactive effect between dose and rate of energy delivery when using combined 464 and 850 nm light to inhibit Pseudomonas aeruginosa.
Methods: Solutions containing P. aeruginosa was irradiated with blue and infrared light (464 and 850 nm). The light energy was applied at two different doses and at two different rates of delivery. The doses employed included 9 and 30 Jcm-2. The rates of delivery used were 20 and 125 mWcm-2.
Design: An in vitro 2 × 2 factorial design was used to compare doses of 9 and 30 Jcm-2 and rates delivery of 20mWcm-2 and 125 mWcm-2 to determine kill rates compared to controls. Each dose was applied at each delivery rate.
Results: Student t-tests demonstrated (p=0.00) a significant kill rate at three of the four combinations. A two-way analysis of variance identified a significant interactive effect between dose and rate (F=94.717, p=0.00). Tukey’s HSD identified 30 Jcm-2 delivered at a 20 mWcm-2 as significantly different from the other combinations.
Conclusions: These data suggest that 1) visible and infrared light may be effective inhibitors of P. aeruginosa, and 2) both dose and rate of delivery are important factors to consider when using visible and infrared light energy to inhibit the growth of this organism.

In the modern day practice of dentistry, it is no longer acceptable to revive single teeth. Patients anticipate a final appearance which is not only physiologically and mechanically sound but also aesthetically pleasing. A gummy smile poses a restorative challenge for dentists attempting to achieve ideal aesthetics. Also, excessive gingival display space is a major concern for a large number of patients visiting the dentist. Cosmetically acceptable smiles show a gingival display of up to 3 mm. Gingival display of greater than 3 mm results in a gummy smile which is often unsightly for the individual and correction is sought. However with the advances in cosmetic dentistry; bleaching, bonding, veneering and laminates have opened doors to a wide variety of elective dental treatments to enhance aesthetic appearance , often reversing the visual signs of aging. A case is reported here on the cosmetic correction of gummy smile wherein periodontal plastic surgery for esthetic crown lengthening was performed in a single appointment using a diode laser and the teeth were restored with laminates for aesthetic enhancement.

Aim: To show how the integration of two highly efficient developed techniques used to reduced orthodontic treatment time in a case that required orthognathic surgery to correct a class III Dento-Maxillo-Facial anomaly. Methods: A 21 years old class-III male patient, with prognathism, macrognathism and mandibular levognathism treated with the following treatment plan: surgical- orthodontic treatment with no extractions, using fixed standard prescription brackets with slot 0.022 × 0.028 inches, Surgery first for mandibular set-back and para-nasal grafts. Low Level Laser extra oral irradiation after surgery and intra oral up to the end of the orthodontic active phase. Retention with Esssix superior and inferior splints. Results: The class-III anomaly was treated in ten months using the “Surgery First” approach and low intensity laser therapy to potentiate the effect in the overall treatment. Conclusion: A class-III Dento-Maxillo-facial anomaly was corrected in a patient during a full treatment time of 10 months, combining the “Surgery First” approached with low level laser therapy to potentiate the effect that both techniques provide to accelerate the rate of tooth movement.