- 标题
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- 实验方案
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Electronically Tunable Distributed Feedback (DFB) Laser on Silicon
摘要： An electronically tunable distributed feedback (DFB) laser heterogeneously integrated on a silicon photonics platform is experimentally demonstrated. Tuning is achieved through carrier injection into the tuning layer of a tunable twin-guide III–V membrane on silicon. A 2 nm continuous tuning range is achieved with a single tuning current. Continuous-wave single-mode laser operation with a side-mode suppression ratio larger than 44 dB across the tuning range is obtained. Measured wavelength switching times are on the order of 3 ns and non-return-to-zero on-o? keying direct modulation at 12.5 Gbit s?1 is readily achieved. This work can be a major advance toward the realization of optical burst or packet switching systems for future data center networks.
关键词： silicon photonics,electronic wavelength tuning,distributed feedback lasers,semiconductor lasers
更新于2025-09-11 14:15:04
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Switchable multi-wavelength fiber laser based on hybrid structure optical fiber filter
摘要： A switchable multi-wavelength fiber laser based on a novel hybrid structure optical fiber filter (HSOFF) is proposed and demonstrated. The HSOFF is consisted of single mode fiber (SMF)-few mode fiber (FMF) with two ellipsoidal structures and FMF-SMF with a core-offset splicing point. Two ellipsoidal structures can effectively excite the high-order modes, then the high-order modes interfere with fundamental mode at the core-offset splicing point. It can be demonstrated that the HSOFF has the comb filter property with the maximum extinction ratio is more than 13 dB while the insert loss is only 9.95 dB. Using HSOFF in proposed laser system, a switchable multi-wavelength fiber laser with stable dual-, triple- and quadruple wavelength lasers can be obtained by adjusting the state of polarization controller, at the same time the lasing wavelength locations also can be switched. The optical signal to noise ratio (OSNR) is larger than 30.68 dB, and this laser exhibits the excellent stability at room temperature.
关键词： Mode interference,Ellipsoidal structure optical fiber,Core-offset,Multi-wavelength fiber laser
更新于2025-09-11 14:15:04
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[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - A wavelength swept laser-based demodulation method for long-distance fiber Bragg grating sensing
摘要： A novel long distance fiber Bragg grating (FBG) demodulation scheme which can eliminate the influence of Rayleigh scattering is proposed. It can detect changes of FBG reflection wavelengths 100km away with an accuracy about 20 pm.
关键词： Rayleigh scattering,FBG demodulation,wavelength measurement,Long distance sensing
更新于2025-09-11 14:15:04
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Ultrafast Dynamics and Ultrasensitive Single-Particle Intermittency in Small-Sized Toxic Metal Free InP Based Core/Alloy-shell/Shell Quantum Dots: Excitation Wavelength Dependency Towards Variation of PLQY
摘要： Observation of strong deviation of photoluminescence excitation curve from absorption curve specially at lower wavelength range, below 450 nm in case of small sized toxic metal free InP based core-alloy-shell quantum dots hints towards interesting exciton dynamics. PL quantum yield (PLQY) has been observed to be dependent on the excitation wavelength. Monitoring the bleach dynamics employing femtosecond ultrafast pump-probe technique it could be shown that the rise-time increases with decrease in pump excitation wavelength from 100 fs for 550 nm excitation to 220 fs for 430 nm pump/excitation. Therefore exciton cooling takes longer time for lower wavelength excitation and thus the exciton becomes more prone to get trapped. About two fold enhancement in magnitude of normalized bleach signal at the band edge (~0.1 (for 430nm excitation) to ~0.2 (for 550nm excitation)) following exciton relaxation has been observed. Thus, in comparison to lower wavelength excitation, for near band-edge pump/excitation there is higher probability of radiative exciton recombination, therefore increasing PLQY. Hot exciton trapping dynamics has been noted to be occurring at a timescale ~750 fs. From ultra-sensitive single particle measurement, magnitude of power-law exponent for both ON and OFF events remain similar to each other and the magnitude remains unaltered for different excitation wavelengths, (405 nm to 568 nm). As long as 100 s ON event could be observed making this InP based non-toxic QD quite suitable for single particle tracking etc. Interestingly, ON event truncation time has been found to increase from 6s to 16s and OFF event truncation time has been found to decrease from 11s to 5.5s, thereby exciton detrapping rate / trapping rate increases from 0.5 to nearly 3 on going from 405 nm to 568 nm excitation. Thus, as the trapping gets suppressed and detrapping gets enhanced, PLQY gets enhanced. The extent of relative decrease of PLQY value with increase in excitation energy above band-edge has been observed to be much more pronounced in CdSe based CAS QD than InP based CAS QD.
关键词： ultrafast dynamics,photoluminescence quantum yield,excitation wavelength dependency,InP based quantum dots,single-particle intermittency
更新于2025-09-11 14:15:04
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Suspended Germanium Waveguide for Infrared Wavelengths
摘要： Silicon-on-insulator (SOI) is the dominant platform in near-infrared silicon photonics. However, the high absorption of SiO2 at wavelengths above 4 μm limits the range at which this material can be used in the mid-infrared wavelengths (2 – 20 μm). In this paper we review our recent investigation on suspended devices, building on our previous work based on suspended silicon devices with sub-wavelength grating (SWG) lateral cladding at 3.8 μm, followed by our more recent results at 7.67 μm. This platform which uses the well-known fabrication techniques of SOI, only requires a single lithographic etch step and it allows the use of the whole transparency range of the waveguide core material. Due to this, it could be a good candidate for sensing applications since the design covers a very large wavelength range. As the bottom cladding of the waveguide is air, the waveguide can be designed so that the mode is squeezed to increase the evanescent field proportion and therefore the interaction with a surrounding analyte.
关键词： waveguides,germanium,sub-wavelength,mid-infrared
更新于2025-09-11 14:15:04
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Transmission Enhanced Wavelength Demultiplexer Design Based on Photonic Crystal Waveguide with Gradually Varied Width
摘要： In this study, we propose the design of photonic crystals with linearly tapered waveguide such that waveguide width is gradually varied. Four drop-channels are included to implement wavelength demultiplexing applications. Here, a tapering of the waveguide has been chosen to localize propagating light within the desired positions. Afterwards, the corresponding drop-channels have been opened to confine the light with the targeted wavelengths. The designed structure consists of cylindrical alumina (Al2O3) dielectric rods and operates at microwave frequencies between 13.2 GHz and 15.3 GHz. An optimization algorithm is applied to enhance transmission efficiencies of the drop-channels and to minimize possible cross-talks between the channels by optimally modulating the position of the dielectric rods inside the channels which form cavity-coupling regions. The optimization algorithm is incorporated with the finite-difference time-domain method to evaluate the transmission efficiencies of the drop-channels for the instant designed structure. The physical mechanism of wavelength demultiplexing is related to slowing down and trapping of light in the tapered waveguide and its coupling to drop-channels for selected microwave wavelengths at different positions. Moreover, an experimental verification of the numerical analyses is demonstrated in the microwave regime and corresponding results will be shared in the conference.
关键词： drop-channels,slow light,microwaves,photonic crystals,optimization,wavelength selective devices
更新于2025-09-11 14:15:04
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Combination of Sclerotherapy and Dual-Wavelength Laser in the Management of Infantile Hemangiomas in Chinese Infants
摘要： OBJECTIVE To evaluate the efficacy and safety of combination therapy with sclerotherapy and dual-wavelength pulsed dye laser (PDL) & Nd:YAG for infantile hemangiomas (IHs). PATIENTS AND METHODS Fifty-nine patients with IH received treatment with sclerotherapy and dual-wavelength PDL & Nd:YAG treatment at 4-week intervals. Observers assessed the size and color of IH using a size rating scale and color rating scale before and after treatments. RESULTS The study showed that IH improved significantly after several sessions of treatment. Sclerotherapy reduced the size of IH, whereas dual-wavelength laser lightened the color of IH. No serious adverse effects occurred. CONCLUSION Combined sclerotherapy and dual-wavelength laser treatment is an effective and safe option for IH.
关键词： infantile hemangiomas,dual-wavelength laser,sclerotherapy,combination therapy
更新于2025-09-11 14:15:04
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Use of Same WDM Channels in Fiber Network for Bidirectional Free Space Optical Communication With Rayleigh Backscattering Interference Alleviation
摘要： In the paper, we present and demonstrate experimentally a 10 Gbit/s on-off keying (OOK) bidirectional wavelength-division-multiplexing (WDM) free space optical (FSO) communication architecture integrated in fiber network together with 5 m free space transmission length and 25 km fiber link, respectively. To achieve bidirectional FSO link, the all WDM wavelengths can be used simultaneously to serve as the downstream and upstream traffics in the proposed FSO-WDM system. Here, four pairs of line terminations (LTs) and optical wireless units (OWUs) are integrated arbitrarily in fiber access network for confidential and bidirectional FSO connection based on the requirement of practical environment. In the measurement, the relationship of FSO signal performance and detected tolerance are also discussed and analyzed. Moreover, the WDM-FSO transmission can also avoid the Rayleigh backscattering (RB) beat noise in fiber connection.
关键词： Free space optical communication,wavelength-division-multiplexing (WDM),Rayleigh backscattering (RB)
更新于2025-09-11 14:15:04
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Long wavelength type II InAs/GaSb superlattice photodetector using resonant tunneling diode structure
摘要： We report on a long wavelength type-II InAs/GaSb superlattice photodetector using resonant tunneling diode (RTD) structure. The linewidth of the satellite peak of the x-ray diffraction curve of the as-grown sample is only 15.7 arcsec showing a very high structural quality. The response maximum wavelength of the RTD detector is 7.5 μm and the 50% cutoff wavelength is 9.6 μm at 77 K. The measured QE is 147% at 7.5 μm when the applied bias voltage is 1.45 V and the corresponding responsivity is 8.9 A/W. This unusual QE is attributed to a large gain achieved when the device is under a resonant tunneling condition. The corresponding shot noise limited detectivity D* is 1.2×1010cm · Hz/W at 1.45 V at 77 K.
关键词： long wavelength,InAs/GaSb superlattice,quantum efficiency,resonant tunneling diode,type II
更新于2025-09-11 14:15:04
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Four-Wave Mixing of a Laser and Its Frequency-Doubled Version in a Multimode Optical Fiber
摘要： It is shown that it is possible to couple a laser beam and its frequency-doubled daughter into a multimode optical ?ber through the four-wave mixing nonlinear process and generate a new wavelength. The frequency-doubled daughter can be generated in an external crystal with a large second order nonlinearity. It is argued that while this possibility is within the design parameter range of conventional multimode optical ?bers, it necessitates a lower-bound for the core-cladding refractive index contrast of the multimode optical ?ber.
关键词： Kerr optical ?ber,third harmonic generation,frequency-doubling,Four-wave mixing,new wavelength generation,multimode nonlinearity
更新于2025-09-11 14:15:04