Chip Laser Research Articles

Fiber–Chip–Fiber Mode/Polarization/Wavelength Transmission and Processing with Few‐Mode Fiber, (de)Multiplexing SiO2 Chip and ROADM Si Chip (Laser Photonics Rev. 18(7)/2024)

Fiber–Chip–Fiber Mode/Polarization/Wavelength Transmission and Processing with Few‐Mode Fiber, (de)Multiplexing SiO₂ Chip and ROADM Si Chip (Laser Photonics Rev. 18(7)/2024)

2.3 J, 25 Hz Nd:YAG/sapphire composite powerchip amplifier operating at room temperature

We demonstrate a sub-nanosecond Joule-class room-temperature diode-pumped solid-state chip laser comprising of periodically bonded Nd:YAG and sapphire crystal plates and operating at 25 Hz, delivering the peak power over 3 GW. In addition, a model describing parasitic oscillations in a composite, high-gain media is developed.

Topic - Use of Chlorhexidine Chip and Diode Laser as an Adjunct to Scaling and Root Planing in Chronic Periodontitis-A Randomised Controlled Clinical Trial

Topic - Use of Chlorhexidine Chip and Diode Laser as an Adjunct to Scaling and Root Planing in Chronic Periodontitis-A Randomised Controlled Clinical Trial

Locally Delivered Chlorhexidine Chip and Diode Laser in the Treatment of Periodontitis

Introduction: Scaling and root planing (SRP) reduces periodontal inflammation but complete removal of bacterial deposits and toxins is not always feasible. Thus, adjunctive therapeutic strategies like use of local delivery of chlorhexidine (CHX) chip and laser therapy have evolved. Objective: To compare effectiveness of locally delivered CHX chip with diode laser in treatment of periodontitis. Methods: The non-randomised trial was done in Department of Periodontics at Peoples Dental College and Hospital (PDCH) from August 2019 to July 2020 after ethical clearance from Nepal Health Research Council. Study population was patients with chronic periodontitis with bilateral periodontal pockets in contralateral hemiarches exhibiting periodontal probing depth (PPD) of ≥5-7 mm attending PDCH. Written informed consent was obtained from all participants. Baseline parameters were recorded one week after full mouth SRP. In group A CHX chip was placed and in group B diode laser treatment was done. The parameters: Oral Hygiene Index-Simplified, Plaque Index, Gingival Index, PPD, and Clinical Attachment Level (CAL) were recorded at one month, three months, and six months. Results: Fifteen patients were analysed. Comparison showed that PPD scores at one month and three months were significantly lower in Group A compared to Group B. Comparison of CAL scores at baseline of both the groups were same. At subsequent visits, CAL for Group A was lower than Group B, but mean difference was not statistically significant. Conclusions: Both groups showed significant improvements compared with baseline. However, the difference in improvement of the PPD and CAL between groups was not significant.

Comparative Evaluation of Azadirachta indica (Neem) Chip and Soft Tissue Diode Lasers as a Supplement to Phase I Periodontal Therapy in Localized Chronic Moderate Periodontitis: A Randomized Controlled Clinical Trial.

Introduction The current trial aimed to assess and compare the efficacy of neem chip and diode laser as a local drug delivery (LDD) agent as a supplement to phase I periodontal therapy in treatment of localized chronic moderate periodontitis. Materials and Methodology. Fourteen systemically healthy participants with 4–6 mm deep periodontal pockets at least in three quadrants (with no alveolar bony defect amenable to respective or regenerative osseous surgery, as seen in orthopantomograph) were selected for the trial. One week after phase I therapy, 10% absorbable chip of neem (commercially prepared by staff of a pharmacy college, Sheriguda, India) was placed in the periodontal pocket on one site, and soft tissue diode laser pocket sterilization was performed on the other site of the arch. Remaining one site was considered as a control. Parameters recorded clinically were plaque index (PI), papillary bleeding index (PBI), probing pocket depth (PPD), and relative attachment level (RAL) measured at baseline, 21st day, and one month postoperatively. Results Statistically significant improvements were observed in all clinical parameters at one month as compared to baseline for both treatment groups. Conclusion Neem chip supplemented with phase I therapy showed best improvement in clinical parameters followed by laser supplemented with phase I therapy in comparison to phase I therapy alone at one month follow-up. Clinical Significance. Neem chips are nature's products, affordable without side effects, with a potential to be used as a local drug delivery agent in treating moderate chronic periodontitis.

COMPARATIVE EVALUATION OF EFFICACY OF SCALING AND ROOT PLANING WITH AND WITHOUT CHLORHEXIDINE CHIP AND DIODE LASER IN CHRONIC PERIODONTITIS PATIENTS

Introduction: The motive of the present study is to comparatively measure the competence and effectiveness of diode laser and chlorhexidine chip as adjuncts to the scaling and root planing procedure, in patients with chronic periodontitis.
 Aim: To evaluate the efficacy of diode laser and chlorhexidine chip before and after scaling and root planing in the management of chronic periodontitis. The objective is to compare the efficacy of chlorhexidine chip and diode laser before and after scaling and root planning on clinical parameters.
 Study and design: Randomized clinical trial with split mouth design done in the Department of Periodontics and Implantology.
 Materials and methods: Twenty chronic periodontitis patients having a probing pocket depth of 5mm-7mm on at least one interproximal site in each quadrant of the mouth were selected in the study. After initial treatment, four sites in each patient were randomly subjected to scaling and root planing (control), chlorhexidine chip application (CHX chip group), diode laser (810 nm) decontamination (Diode laser group) or combination of both (Diode laser and chip group). All subjects received a clinical periodontal examination by single examiner who recorded all the variables by manual procedure. Clinical parameters namely Plaque index (PI), Gingival Index (GI), probing pocket depth (PPD) and clinical attachment level (CAL) were assessed at baseline, one month and three months. Results were statistically analysed using one-way ANOVA followed by Post Hoc Analysis.
 Results: The differences in PPD reduction and CAL gain between control group and CHX chip and combination groups were statistically significant (p<0.05) at three months, whereas, the diode laser group did not show any significant difference from the control group.
 Conclusion: Within the limitations in the present study, the following conclusions were derived, i.e., chlorhexidine local delivery alone or in combination with diode laser decontamination is effective in improving oral hygiene, reducing gingival inflammation, reducing probing pocket depth and improving clinical attachment levels when used as adjuncts to scaling and root planing in non-surgical periodontal therapy of patients with chronic periodontitis.
 Keywords: Diode laser decontamination, Local drug delivery, Scaling and root planing.

Compact actively Q-switched laser for sensing applications

Current active Q-switching is mainly generated by acousto-optical modulators (AOMs) or electro-optical modulators (EOMs). However, EOMs make the setup bulky, while AOMs require the radiofrequency (RF) signal and water-cooling. We present a novel approach to active Q-switching of an integrated waveguide chip laser by utilizing a deformed helix ferroelectric liquid crystal cell (6mm×6mm) with a thickness of 2 mm. This device can be directly integrated onto the Ytterbium-doped waveguide chip and controlled by the electrical signal. In experiments, with an electrical signal with a pulse duration of 2 μs and a magnitude from 10 V to 84 V, the Q-switched lasers can be observed at a repetition rate ranging from 0.1 kHz to 20 kHz. The shortest pulse duration and the maximum slope efficiency is 38 ns and 22% respectively. This novel integrated and low-cost laser source is a promising tool for a broad range of applications such as gas sensing and LIDAR.

An Effective Simulation Analysis of Transient Electromagnetic Multiple Faults.

Embedded encryption devices and smart sensors are vulnerable to physical attacks. Due to the continuous shrinking of chip size, laser injection, particle radiation and electromagnetic transient injection are possible methods that introduce transient multiple faults. In the fault analysis stage, the adversary is unclear about the actual number of faults injected. Typically, the single-nibble fault analysis encounters difficulties. Therefore, in this paper, we propose novel ciphertext-only impossible differentials that can analyze the number of random faults to six nibbles. We use the impossible differentials to exclude the secret key that definitely does not exist, and then gradually obtain the unique secret key through inverse difference equations. Using software simulation, we conducted 32,000 random multiple fault attacks on Midori. The experiments were carried out to verify the theoretical model of multiple fault attacks. We obtain the relationship between fault injection and information content. To reduce the number of fault attacks, we further optimized the fault attack method. The secret key can be obtained at least 11 times. The proposed ciphertext-only impossible differential analysis provides an effective method for random multiple faults analysis, which would be helpful for improving the security of block ciphers.

Additive-free Y2O3:Eu3+ red-emitting transparent ceramic with superior thermal conductivity for high-power UV LEDs and UV LDs

To obtain red-emitting luminescent material for high-power UV LED and UV LD applications, an additive-free Y2O3:Eu3+ phosphor ceramic was successfully prepared in this work. The nitrate pyrogenation method is applied to obtain raw nanopowders with high reactivity, and a hybrid sintering method combining low-temperature presintering and subsequent hot isostatic pressing (HIP) is then applied to realize full densification of the final ceramic products. The effects of the presintering temperature on the density, microstructural, and optical properties are investigated in detail. The HIP-treated Y2O3:Eu3+ ceramic presintered at 1450 °C exhibits a high transmittance near 80 % at 600 nm. Due to the nonuse of sintering additives, the thermal conductivity of Y2O3:Eu3+ ceramic product reaches 10.9 Wm−1 K−1 at room temperature. The achieved Y2O3:Eu3+ ceramic also exhibits good applicability under the excitation of a UV LED chip and UV laser light, showing promise as a color converter for high-power UV LED and UV LD applications.

Single-frequency mid-infrared waveguide laser.

A guided-wave chip laser operating in a single longitudinal mode at 2860 nm is presented. The cavity was set in the Littman-Metcalf configuration to achieve single-frequency operation with a side-mode suppression ratio above 33 dB. The chip laser's 2 MHz linewidth on a 10 ms scale was found to be limited by mechanical fluctuations, but its Lorentzian contribution was estimated to be lower than 1 Hz using a heterodyne technique. This demonstration incorporates a high coherence source with the simplicity provided by the compactness of chip lasers.

An ultra-stable 2.9 μm guided-wave chip laser and application to nano-spectroscopy

We present a configurable guided-wave planar glass-chip laser that produces low-noise and high-quality continuous-wave laser emission tunable from 2.82 to 2.95 µm. The laser has a low threshold and intrinsic power and mode stability attributable to the high overlap of gain volume and pump mode defined by an ultrafast laser inscribed waveguide. The laser emission is single transverse-mode with a Gaussian spatial profile and M2x,y ∼ 1.05, 1.10. The power drift is ∼0.08% rms over ∼2 h. When configured in a spectrally free-running cavity, the guided-wave laser emits up to 170 mW. The benefit of low-noise and stable wavelength emission of this hydroxide resonant laser is demonstrated by acquiring high signal-to-noise images and spectroscopy of a corroded copper surface film with corrosion products containing water and hydroxide ions with a scattering-scanning near-field optical microscope.

Low-dimensional nanomaterial saturable absorbers for ultrashort-pulsed waveguide lasers

A wide range of saturable absorbers composed of novel low-dimensional nanomaterials were fabricated, and their linear and nonlinear optical properties were characterized. Furthermore, their suitability for ultrashort-pulse generation in waveguide laser operating at a wavelength of 2 microns was demonstrated and passively q-switched mode-locked operation was achieved with all absorbers. The material systems that were studied in this work include nanosheet-based absorbers composed of graphene, carbon nanotubes, black phosphorus, transition-metal dichalcogenides, topological insulators and indium tin oxide. By utilizing a uniform few-layer spin coating fabrication technique and by employing a single, identical laser resonator, a direct comparison of the individual characteristics of these materials in the context of short-pulse generation in waveguide lasers was made possible. Each of the individually fabricated and characterized saturable absorbers was placed inside a thulium-doped fluoride glass waveguide chip laser cavity and the resulting output performance was analyzed and contrasted. It was further found that the few-layer spin coating approach enables fine-tuning of the absorber characteristics and that all low-dimensional nanomaterials under investigation can be utilized for ultrashort pulse generation in the 2-micron wavelength range. General guidelines for the design of passively modulated short-pulsed laser oscillators are presented based on those findings.

A clinico-microbiologic study comparing the efficacy of locally delivered chlorhexidine chip and diode LASER as an adjunct to non-surgical periodontal therapy

BackgroundConsidering the microbial etiology of the periodontal disease, the periodontal therapy aims to control or abolish the pathogenic microbes. The gold standard scaling and root planing procedure has been used since time immemorial but the drawbacks associated with it have led to the development of various adjunctive means. The current study was therefore, performed to comparatively assess the efficacy of local delivery of chlorhexidine and 808-nm diode LASER as an appurtenance to scaling and root planing in patients with chronic periodontitis. MethodsIn a randomized split mouth evaluation, 30 patients having probing depth of ≥5 mm which bled on probing at least at 3 different sites were included. At baseline, the evaluation of plaque index, bleeding index, probing pocket depth and clinical attachment level was done and the microbial samples were collected for the assessment of spirochetes, motile rods and coccoid cells. The 3 selected sites of each subject were allocated to 3 different groups A, B, C viz; Scaling and root planing (SRP) + chlorhexidine chip, SRP + diode LASER and SRP respectively. The patients were recalled after 4 weeks to re-evaluate the clinical and microbiological parameters. ResultsAll the parameters significantly reduced from baseline to 4 weeks in all the 3 groups. Intergroup comparisons revealed remarkable difference between group A and C and group B and C, respectively; no notably significant difference was found between group A and B. ConclusionThe additional use of LASER and chlorhexidine chip assures anti-inflammatory effect and anti-microbial effect that allows reduction in bacterial counts and promotes healing. The use of adjuncts have been found to be efficacious in controlling disease and promoting periodontal health and thereby reducing the need for surgical procedures to be undertaken.

Visible laser emission from a praseodymium-doped fluorozirconate guided-wave chip.

We report visible continuous-wave laser emission at 636 nm from a praseodymium-doped fluorozirconate glass guided-wave chip laser. This ultra-fast laser inscribed gain chip is demonstrated to be a compact and integrated laser module. The laser module, pumped by 442 nm GaN laser diodes, generates >8 mW lasing output with a beam quality of Mxy2∼1.15×1.1(±0.1). To the best of our knowledge, this is the first visible laser emission from a glass-based waveguide chip laser.

Widely tunable, narrow linewidth external-cavity gain chip laser for spectroscopy between 1.0 - 1.1 µm.

We have developed and characterised a stable, narrow linewidth external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a single-angled-facet gain chip. We propose the ECL as a low-cost, high-performance alternative to fibre and diode lasers in this wavelength range and demonstrate its capability through the spectroscopy of metastable helium. Within the coarse tuning range, the wavelength can be continuously tuned over 30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz (piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5 ms, while a long-term frequency stability better than 40(20) kHz over 11 hours was observed when locked to an atomic reference.

Time-Scale Independent Permutation Entropy of a Photonic Integrated Device

A new measure of complexity, time-scale independent permutation entropy, has been developed and applied to fully characterize the relative complexity of the emission of a four-section photonic integration chip (PIC) laser. The new technique allows the relative complexity of dynamics with different characteristic time scales to be compared. The analysis reveals the range of possible outputs the PIC device can produce over a three-dimensional operating parameter space. From the perspective of using such devices as synchronized transmitter and receiver pairs in chaos-based secure communication applications, a region of uninterrupted, highly complex, unpredictable dynamics has been identified for the device. Regions surrounding this desired complex state show intermittency, pulse packages, and limit-cycle oscillations. The effect of varying the laser's biasing current, feedback strength, and feedback phase reveals the extent of the short-cavity regime and provides insight to the fundamental physics driving the integrated device dynamics.

Er3+Active Yb3+Ce3+Co-Doped Fluorozirconate Guided-Wave Chip Lasers

We report efficient 1.55-μm laser operation in a waveguide chip laser femtosecond-laser inscribed in bulk fluorozirconate glass. The ternary doped glass is composed of erbium as the active laser ion, ytterbium sensitizer, and cerium to enhance the branching ratio from the pump to the erbium upper laser state. We have achieved slope efficiencies up to 25%, with a low 100-mW threshold. To meet diverse application requirements, we also report the wide tunability of 1507-1593 nm, and large single-transverse-mode Gaussian beam-output from the 55 μm diameter waveguides.

Bismuth telluride topological insulator nanosheet saturable absorbers for q‐switched mode‐locked Tm:ZBLAN waveguide lasers

Nanosheets of bismuth telluride (Bi2Te3), a topological insulator material that exhibits broadband saturable absorption due to its non‐trivial Dirac‐cone like energy structure, are utilized to generate short pulses from Tm:ZBLAN waveguide lasers. By depositing multiple layers of a carefully prepared Bi2Te3 solution onto a glass substrate, the modulation depth and the saturation intensity of the fabricated devices can be controlled and optimized. This approach enables the realization of saturable absorbers that feature a modulation depth of 13% and a saturation intensity of 997 kW/cm2. For the first time to our knowledge, Q‐switched mode‐locked operation of a linearly polarized mid‐IR ZBLAN waveguide chip laser was realized in an extended cavity configuration using the topological insulator Bi2Te3. The maximum average output power of the laser is 16.3 mW and the Q‐switched and mode‐locked repetition rates are 44 kHz and 436 MHz, respectively.

Management of Chronic Periodontitis Using Chlorhexidine Chip and Diode Laser-A Clinical Study.

The use of adjuncts like chlorhexidine local delivery and diode laser decontamination have been found to improve the clinical outcomes of scaling and root planing in non-surgical periodontal therapy in patients with chronic periodontitis. To evaluate the effects of diode laser and chlorhexidine chip as adjuncts to scaling and root planing in the management of chronic periodontitis. The objective is to evaluate the outcome of chlorhexidine chip and diode laser as adjuncts to scaling and root planing on clinical parameters like Plaque Index, Gingival Index, probing pocket depth and clinical attachment level. Department of Periodontics. Randomized clinical trial with split mouth design. Fifteen chronic periodontitis patients having a probing pocket depth of 5mm-7mm on at least one interproximal site in each quadrant of the mouth were included in the study. After initial treatment, four sites in each patient were randomly subjected to scaling and root planing (control), chlorhexidine chip application (CHX chip group), diode laser (810 nm) decontamination (Diode laser group) or combination of both (Diode laser and chip group). Plaque Index (PI), Gingival Index (GI), probing pocket depth (PPD) and clinical attachment level (CAL) were assessed at baseline, one month and three months. Results were statistically analysed using paired T test, one-way ANOVA, Tukey's HSD test and repeated measure ANOVA. Post-treatment, the test and control sites showed a statistically significant reduction in PI, GI, PPD, and CAL. After three months, a mean PPD reduction of 1.47±0.52 mm in control group, 1.40±0.83 mm in diode laser group, 2.67±0.62 mm in CHX group, and 2.80± 0.77 mm in combination group was seen. The mean gain in CAL were 1.47±0.52 mm in the control group, 1.40±0.83 mm in diode laser group, 2.67± 0.49 mm in CHX group and 2.67± 0.82 mm in combination group respectively. The differences in PPD reduction and CAL gain between control group and CHX chip and combination groups were statistically significant (p<0.05) at three months, whereas, the diode laser group did not show any significant difference from the control group. Chlorhexidine local delivery alone or in combination with diode laser decontamination is effective in reducing probing pocket depth and improving clinical attachment levels when used as adjuncts to scaling and root planing in non-surgical periodontal therapy of patients with chronic periodontitis.

Holmium-doped 21 μm waveguide chip laser with an output power &gt; 1 W

We demonstrate the increasing applicability of compact ultra-fast laser inscribed glass guided-wave lasers and report the highest-power glass waveguide laser with over 1.1 W of output power in monolithic operation in the short-infrared near 2070 nm achieved (51% incident slope efficiency). The holmium doped ZBLAN chip laser is in-band pumped by a 1945 nm thulium fiber laser. When operated in an extended-cavity configuration, over 1 W of output power is realized in a linearly polarized beam. Broad and continuous tunability of the extended-cavity laser is demonstrated from 2004 nm to 2099 nm. Considering its excellent beam quality of M² = 1.08, this laser shows potential as a flexible master oscillator for single frequency and mode-locking applications.