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Narrow linewidth DBR laser based on high order Bragg grating defined by i-line lithography
摘要： In order to obtain narrow linewidth semiconductor laser around 1564 nm, we design a distributed Bragg reflector (DBR) laser with high-order Bragg gratings (HOBGs) using butterfly encapsulation. The DBR laser is fabricated only by i-line lithography technology with grating period of 4.84 μm, groove width of 1.5 μm and grating length of 72 μm on a strip width of 4 μm. The 1mm-long devices achieved an output power of 9.9 mW and a side mode suppression ratio (SMSR) more than 30 dB without facet coating at an injection current of 80 mA. The lasers showed ultra-narrow Lorentz linewidth of 70 KHz. This paper provides a simple method for large-scale production of narrow linewidth semiconductor lasers.
关键词： narrow linewidth spectrum,Semiconductor laser,high-order grating,distributed Bragg reflector laser
更新于2025-11-28 14:23:57
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Analysis of optical injection on red and blue laser diodes for high bit-rate visible light communication
摘要： In this work, self-injection and external-injection in ～450 nm InGaN/GaN blue and ～650 nm InGaP/AlGaInP red diode lasers are investigated. A distinct locking characteristic is observed in the self-injection case with small 19 cm cavity length, demonstrating enhanced ～2.34 and ～2.07 GHz 3-dB bandwidths, corresponding to a factor of ～1.4 and ～1.1 improvement, and reduced ～60 and ～80 pm spectral linewidths, for the blue and the red lasers, respectively. Moreover, this short external cavity self-injection locked system exhibited superior performance by a factor of 1.1–1.3 compared to the long cavity (26 cm) configuration. Conversely, the external optical injection exhibited weak locking signature with improved linewidths by a factor of ～1.6–2.8 and reaching as small as ～70 and ～87 pm for the blue laser, respectively, while almost doubling in the peak powers. Later, on–off keying modulation technique based data transmission rates of up to 3.5 and 4.5 Gb/s are demonstrated on free-running blue and red laser diodes, respectively, employing an in-house laser diode mount based system. Moreover, owing to the bandwidth limitation of the optically injected systems, successful transmission of up to 2 Gb/s is demonstrated with better performance compared to the respective free-running cases, in particular, the external-optically injected system demonstrated more than double improvement in the bit-error-rate.
关键词： Visible light communication,Semiconductor laser diodes,External optical injection,Self-injection locking
更新于2025-11-28 14:23:57
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Narrow-Strip 670 nm Gain-Coupled Distributed Feedback Laser Based on Periodic Anodes Fabricated by I-Line Lithography
摘要： A narrow-strip single-longitudinal-mode gain-coupled distributed feedback semi-conductor laser with a central wavelength of approximately 670 nm is demonstrated. We fabricate a novel micro-scale regrowth-free gain-coupled grating with an island-like shape without nanoscale gratings by i-line lithography only. The maximum output power from the ?ber of the device with butter?y package is 48.1 mW at 100 mA and its slope ef?ciency is 0.79 W/A. The laser can be continuously tuned from 670.750 to 670.784 nm with a side-mode suppression ratio of over 40 dB, covering the absorptive peak of lithium atoms. Our easily fabricated devices have great potential as light sources in many applications such as lithium atom detectors.
关键词： continuous tunability,gain-coupled,distributed-feedback,Semiconductor laser
更新于2025-11-28 14:23:57
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Inducing tunable single-mode operation of Fabry-Perot semiconductor laser coupled with very-short cavity with selective optical feedback
摘要： We report on achieving tuned single mode operation of a multimode semiconductor laser by coupling it to a very-short external cavity with selective feedback. We show that the induced uniform feedback light from the very-short external cavity can induce single-mode oscillation over a broad range of optical feedback. Then by applying selective external to the optimum settings of the single-mode oscillation, we predict tuning of the single-mode output over a wavelength range of ~ 20 nm by detuning the peak wavelength of optical feedback from the central wavelength of the modal gain. The study is based on modeling of the dynamics of multimode semiconductor laser subject to selective optical feedback. The model takes into account mechanisms of both self- and cross-modal gain suppression, and the study is concerned with the very-short external cavity that corresponds to stable continuous-wave (CW) operation.
关键词： Optical feedback,Semiconductor laser,Multimode laser,Optical gain
更新于2025-09-23 15:21:01
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The efficacy and safety of a 577a??nm higha??power optically pumped semiconductor laser in the treatment of postacne erythema
摘要： Background: Postacne erythema (PAE) is a common sequela of inflammatory acne vulgaris. Treatment of which has been challenging due to limited options available and the variability of results for each modality. Recently, a 577-nm high-power optically pumped semiconductor laser (HOPSL) initially developed for vascular lesions, has shown promising results for the treatment of PAE. Objective: To evaluate the efficacy and safety of 577-nm HOPSL in the treatment of postacne erythema. Materials and Methods: This was a split-face, randomized controlled trial pilot study. Twenty-one patients with PAE on both sides of their face were enrolled. Each subject’s face sides were randomly assigned to either receive 577-nm HOPSL treatment (QuadroStar PROTM, Asclepion Laser Technologies, Jena, Germany) using the scanner handpiece, 1mm spot size, 80% coverage, 12-15 J/cm2, 30 ms, 2 passes for 3 sessions at 1-month intervals, or no treatment at all. Outcome measures such as overall improvement, the Erythema Index (EI) and Melanin Index (MI) from 3 different areas on both treatment and control sides were assessed at baseline, and 1-month follow-up after each treatment session. Side effects including pain, erythema, swelling, and crusting were also recorded. Results: Upon completion of the treatment period, the mean EI was significantly decreased in both treated and non-treated sides of the face (p<0.001 and p=0.001, respectively). The laser-treated sides already demonstrated significant reduction in the mean EI compared to non-treated sides at 1 month after the 2nd treatment (p=0.007). The mean MI of both sides; however, did not show any statistically significant differences from baseline, and likewise when comparing between sides. Patients reported more improvement on laser-treated sides compared to non-treated sides. Reported side effects were limited to mild discomfort during treatment and transient facial erythema lasting approximately 30 minutes. Conclusion: Patients who received treatment with the 577-nm HOPSL had better outcomes with minimal side effects at 1 month after 2 treatments as compared to those who did not receive any treatment. Therefore, the 577-nm HOPSL may be considered as an effective adjuvant treatment for PAE and early erythematous atrophic scars.
关键词： Vascular-specific laser,577-nm high-power optically pumped semiconductor laser (HOPSL),Postacne erythema
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering, Information and Communication Technologies (CHILECON) - Valparaiso, Chile (2019.11.13-2019.11.27)] 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering, Information and Communication Technologies (CHILECON) - Fourier-Bessel Shapes in Output Photocurrents and Frequency Chirping Effects from Laser Fields
摘要： Record low values in this material system of threshold current density, particularly at elevated temperature, are presented for InP quantum dot lasers. Lasers with Ga0 .5 8 In0 .4 2 P in the dot upper con?ning layer have the lowest threshold current densities, 138 A·cm?2 at 300 K, and 235 A·cm?2 at 350 K (77 °C) (2-mm lasers, uncoated facets). Gain-current density data suggests laser performance with an upper con?ning layer of Gax In1 ?xP with x = 0.54, 0.56 or 0.58 would be similar if not for the very low internal optical mode loss, αi of samples with x = 0.56 and 0.58. Gain measurements at ?xed inversion level suggest that increasing x content in Gax In1 ?xP increases gain at ?xed inversion level but samples with x = 0.54 also exhibit reduced recombination current density. The increasing recombination current density at elevated temperature due to thermal carrier spreading is signi?cantly reduced in samples with x = 0.56 and x = 0.58 but measurements at common operating points attribute this largely to the reduced αi for these samples and given the same αI , samples with x = 0.54, 0.56 and 0.58 would all bene?t from reduced effects due to thermal carrier spreading compared to x = 0.52.
关键词： Quantum dot devices,InP self-assembled quantum dots,semiconductor laser,short wavelength lasers,threshold current density,temperature sensitivity
更新于2025-09-23 15:21:01
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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - Inter-modal Laser Based RF Output Stabilization Using Forced SILPLL Technique
摘要： Low phase noise oscillator is very important for communication and high-resolution imaging system. A small size synthesizer realization using inter-modal output of multi-mode semiconductor laser is proposed and tested in this paper. It uses the forced technique self-injection locking, self-phase locking combination to stabilize the related inter-modal output. The realized phase noise is -98 dBc/Hz at 10 kHz offset at X-band operation which shows 68 dB improvement comparing with inter-modal free running output.
关键词： inter-modal output,multi-mode semiconductor laser,synthesizer,phase noise,self-phase locking,self-injection locking
更新于2025-09-23 15:21:01
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Deformation and removal of semiconductor and laser single crystals at extremely small scales
摘要： Semiconductor and laser single crystals are usually brittle and hard, which need to be ground to have satisfactory surface integrity and dimensional precision prior to their applications. Improvement of the surface integrity of a ground crystal can shorten the time of a subsequent polishing process, thus reducing the manufacturing cost. The development of cost-effective grinding technologies for those crystals requires an in-depth understanding of their deformation and removal mechanisms. As a result, a great deal of research efforts were directed towards studying this topic in the past two or three decades. In this review, we aimed to summarize the deformation and removal characteristics of representative semiconductor and laser single crystals in accordance with the scale of mechanical loading, especially at extremely small scales. Their removal mechanisms were critically examined based on the evidence obtained from high-resolution TEM analyses. The relationships between machining conditions and removal behaviors were discussed to provide a guidance for further advancing of the grinding technologies for those crystals.
关键词： semiconductor,laser crystal,deformation and removal,transmission electron microscopy (TEM),grinding
更新于2025-09-23 15:21:01
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Efficient and Higha??Brightness Broad Area Laser Diodes Designed for Higha??Temperature Operation
摘要： Efficient and High-Brightness Broad Area Laser Diodes Designed for High-Temperature Operation. Advantages of semiconductor laser diodes as efficient high-power laser light sources applicable at elevated ambient temperatures. Semiconductor laser diodes, manufactured as single emitters or laser bars, are highly desired light sources for direct material processing as well as optical pumping of fiber and solid-state lasers. Laser diodes feature high optical output power and efficiency, long lifetimes, low maintenance and consequently low cost of ownership. To improve the usability and extend the application spectrum of high-power laser diodes, relaxed cooling requirements – without compromise in laser performance and lifetime – are required. Therefore, great development efforts are made, both in externally and internally funded research projects, to push the maximum permissible operating temperature of such semiconductor laser diodes to higher levels.
关键词： efficiency,semiconductor laser diodes,high-power laser,brightness,high-temperature operation
更新于2025-09-23 15:19:57
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Chaotic Synchronization of Mutually Coupled Lasers with Another Laser and Its Encoding Application in Secret Communication
摘要： A chaotic synchronization based on mutually coupled different semiconductor lasers and its coding communications are studied. A route to chaos is illustrated by a bifurcate diagram. Chaotic distribution is presented in two lasers. The synchronization equation is given in theory. A chaotic synchronization is obtained between the emitter and the receiver. Other complex dynamical behavior synchronizations are also obtained, such as period-5 and period-10 synchronizations. Cascade synchronizations are achieved. A novel On/Off coding system is presented while its chaotic phase encoding is successfully implemented. Chaos key is also numerically simulated. We find that synchronization can still be achieved when the parameter of the emitter changes at any time so that the newly generated chaotic carrier can ensure mask the information in each communication. Then the real-time variable parameter results in difficulty for eavesdroppers to decipher. Compared with a single laser emitter, this emitter has many secret keys and high security, which is beneficial to its potential application in secret communication.
关键词： mutually-coupled laser,chaotic synchronization,semiconductor laser,coding
更新于2025-09-23 15:19:57