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Dislocation reduction in AlInSb mid-infrared photodiodes grown on GaAs substrates
摘要： We investigated the electrical and optical properties of a highly mismatched AlInSb/GaAs photodiode sensor working in the mid-infrared range at room temperature. A substantial increase in the device performance was achieved by controlling the strain energy density in the dislocation ?lter layers and barrier layers to reduce the density of threading and interfacial dislocations, respectively. The resulting photodiode showed a high resistance-area product of 0.24 Ω cm2 and a peak detectivity of 2.2 × 109 cm Hz1/2 W–1 at 3.3 μm.
关键词： AlInSb,GaAs substrates,photodiode,dislocation reduction,mid-infrared
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Broadband Multi-Species Trace Gas Detection by Up-Converting Mid-Infrared Supercontinuum Light into the Near-Infrared
摘要： Recent advancement in compact, stable, and broadband mid-infrared supercontinuum (SC) sources has provided attractive scientific and industrial applications in metrology, sensing, and communications [1]. The wide spectral coverage in the so-called molecular fingerprint region is the main advantage of such SC sources, opening up new opportunities for efficient multi-species trace gas detection at short time scale. Presently, there is a lack of sensitive, low-cost, uncooled MIR photodetectors. The alternative approach involves up-converting mid-infrared light into the near-infrared region via non-linear conversion, leveraging the benefits of sensitive and cost-effective CCD detectors [2]. Here, we present the development of a multi-species trace gas sensor utilizing a mid-infrared SC source in combination with a multipass absorption cell and an up-conversion-based spectrometer. The customized SC source (NKT Photonics) has a total power of 450 mW covering the 1.5 – 4.5 μm spectral window. The astigmatic Herriott multipass cell (AMAC-76, Aerodyne Research) provides an effective optical pathlength of 76 meters improving the detection sensitivity. Details of the up-conversion-based spectrometer (NLIR) have been recently published. [3]. Note that in the present upconversion system the intracavity laser at 1064 nm is generated by pumping the Nd:YVO4 gain medium at 808 nm instead of 880 nm. In order to enhance the long term stability for single species detection, the amplitude drift of the SC source is minimized by counterbalancing the SC intensity with a non-absorbing reference. Multispecies broadband absorbance spectra have been obtained for, amongst others, mixtures of ethane and acetaldehyde at ppm levels in nitrogen as shown in Fig. 1 (a). A non-negative least squares global fitting method has been applied to extract the concentration of individual sub-component. To check system linearity by different gas concentrations, the absorbance with various mixing ratios were measured at a pressure of 900 mar for 60 s. A linear fit of these measurements that agreed with the calculated ones is depicted in Fig. 1 (b) for ethane. The sensor is capable of detecting sub-ppmv gas concentrations (e.g. ~300 ppbv ethane) in a wide range of spectrum (over 600 cm-1) with a ~5 cm-1 spectral resolution. Broadening the spectrum to a wider range by using chirped crystals in the up-converter system and further experiments are under progress. More details and the results for the on-going experiments will be presented at the conference.
关键词： multi-species,mid-infrared supercontinuum,up-conversion,broadband,trace gas detection
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Breath Signatures of Cerebral Palsy Patients Revealed with Mid-Infrared FTIR Spectroscopy
摘要： In the absence of “broadband” objective medical diagnostics, photonics technologies are now considered as a promising way to establish it. For example, being applied to human breath, under right conditions they should allow for unambiguous identification of metabolites circulating in blood and released in lungs alveoli as volatile organic compounds (VOCs). Nowadays, tremendous progress is achieved in developing laser-based mid-infrared spectrometers highly sensitive to VOCs [1,2]. Still, the spectral range covered by the laser spectrometers demonstrated so far, and signal-to-nose ratio (SNR) are not superior to conventional FTIR spectrometers based on thermal source. A significant amount of water vapour in breath is another, though general for all techniques, severe problem for VOCs detection. In addition to the detection, data analysis should be advanced in order to accurately compare healthy and diseased cohorts under study.
关键词： cerebral palsy,FTIR spectroscopy,mid-infrared spectroscopy,breath analysis,VOCs
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Mid-Infrared Photon Counting by Intra-Cavity Up-Conversion for LIDAR
摘要： In range resolved differential absorption LIDAR for gas concentration measurement, an attractive solution would be mid-infrared (MIR) micro-pulse LIDAR with photon counting detection. Single-photon detection in MIR is, however, difficult because of the low photon energy. Both superconducting nanowire detectors and low bandgap APDs need cryogenic cooling and are still limited to wavelengths shorter than approximately 2.5 μm. On the other hand, silicon-based single photon avalanche diodes (Si-SPAD) for the visible and near infrared (NIR) wavelength range operate at room temperature with desirable properties such as good timing resolution, low dark count rate and short dead-time. Nonlinear up-conversion through sum frequency generation (SFG) can be used to transfer single-photons from MIR to wavelengths detectable by a Si-SPAD. The appropriate SFG up-conversion is obtained by mixing with visible or NIR photons in a nonlinear crystal, either in a single pass configuration [1], or inside a laser cavity [2]. In the latter case, the high intra-cavity power enables efficient conversion. Of particular interest is to exploit the quasi-phase matching (QPM) scheme. The crystals can then be engineered for colinear interaction at the required wavelengths and bandwidth. A typical 10 mm long QPM crystal has a MIR bandwidth of about 10 nm only, which with proper filtering gives a low background noise. In this work, a periodically poled Rb-doped KTiOPO4 (PPRKTP) crystal was used to convert pulses at 2.4 μm to 737 nm by intra-cavity mixing with 1,064 nm from a Nd:YVO4 laser. A sketch of the cavity and the detection scheme can be seen in Fig. 1 (a). The cavity consists of three mirrors and the Nd:YVO4 laser crystal which also acts as the input coupler. The plane mirrors have high transmission for the MIR and the generated wavelength. The Fresnel reflections at the surfaces of the uncoated PPRKTP crystal were calculated to be 8.6%, which corresponds to a 30% loss per round-trip. The 1.064 nm beam had a 1/e2 radius of 150 μm and a power of about 10 W inside the crystal. The MIR pulses had a pulse energy in the order of 1 nJ, a duration of around 60 fs and a repetition rate of 1 kHz. They were focused down into the PPRKTP crystal and the light leaving the cavity was filtered to remove the other wavelengths and a Si-SPAD was used to detect the 737 nm pulses. Even though the 737 nm pulses were attenuated by at least 50 dB, the Si-SPAD detector was fully saturated, i.e. every single pulse of 2.4 μm radiation triggered the detector. The quantum efficiency of the detector was 27 % and the dead-time was 77 ns. This indicates that substantially weaker pulses could be detected with this method. The pulses were detected with a timing resolution of 140 ps, which corresponds to a spatial resolution of 20 mm for LIDAR. The detector response when the 1.064 nm laser was either on or off can be seen in Fig. 1 (b). The temporal resolution was mainly determined by the trigger jitter in the electronics for the Si-SPAD. Nonetheless, this is, to our knowledge, the best timing resolution for detection of pulses in the MIR region by up-converting the MIR photon inside a cavity.
关键词： mid-infrared,up-conversion,photon counting,single-photon detection,LIDAR
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Optimization of the Efficient Single Pass Two-Stage DFG of Er and Yb Fiber Lasers Radiation into Mid-Infrared Region
摘要： High power laser radiation sources with wavelengths near 3 μm are indispensable for processing of organic and high water-containing materials. These wavelengths belong to mid-infrared (mid-IR) range, which is also called molecular footprint region. Where the absorption peaks of water and hydrogen bonds are located, that provides many opportunities for the application in biology, medicine and non-metal material processing [1]. Direct generation of mid-IR radiation associated with a number of difficulties. The main one among them is the limited choice of the active gain media with a transparency window in this range. The other way to obtain these wavelengths is a nonlinear parametric conversion. In particular, difference frequency generation (DFG) in periodically poled niobate or tantalate lithium (PPLN or PPLT) crystals [2]. Relatively high nonlinearity, transparency in the desirable spectral region, photorefractive damage resistance with MgO doping and possibility of using the quasi-phase-matching (QPM) technique by periodic poling allows them to pretend on a leading role for developing mid-IR radiation sources. The single pass OPO process for 1 μm radiation without seed provides a low pump to idler conversion efficiency. Even with seed presence it fundamentally limited about 30% by photons energy relations. We improve DFG efficiency of Yb pump (1.03 μm) and Er seed (1.5 μm) fiber lasers to mid-IR by adding the second stage [3]. After the first stage, the parametrically amplified seed used as a pump, and mid-IR idle became a new seed for the second conversion process. This approach allowed us experimentally reach overall 20 W mid-IR radiation power with a more than 50% pump conversion efficiency at 3.05 μm and 3.19 μm wavelengths.
关键词： mid-infrared,fiber lasers,DFG,QPM,PPLT,PPLN
更新于2025-09-16 10:30:52
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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) - Active Hyperspectral Mid-Infrared Imaging Based on Widely Tunable QCL Laser
摘要： Thermal imaging and the recent availability of widely tunable infrared QCL lasers (Quantum Cascade Laser) allow us to propose an active hyperspectral imaging system operating in mid-infrared (MIR) band to obtain simultaneously large amounts of spatial and spectral information on the samples. In order to evaluate more precisely the capacities of the active hyperspectral imaging, we propose a system composed of four powerful QCL tunable lasers (in order to cover 3 – 5 μm and 7 – 11 μm wavelengths) and three cameras: a visible and near-infrared (NIR) range, a bolometer for 7 – 13 μm range and an InSb cooled camera for 3 – 5 μm range. We present the algorithm for image acquisition, image and data processing. Finally, we present and discuss some preliminary results using this system to characterize plant leaves under controlled growing conditions.
关键词： plant monitoring,tunable QCL laser,mid-infrared,hyperspectral imaging,image processing
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Shenzhen, China (2019.9.3-2019.9.6)] 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Theoretical Evaluation of a Pulsed Mid-Infrared Ho <sup>3+</sup> :BaY <sub/>2</sub> F <sub/>8</sub> Laser
摘要： In this study, we construct a theoretical model to analyze the output characteristics of a pulsed Ho3+:BaY2F8 (Ho3+:BYF) laser by taking both energy transfer up-conversion (ETU) and cross relaxation (CR) processes into account. The influences of the pump energy, pulse width, reflectance of an output coupler (OC), crystal length, and Ho3+ doping concentration on the physical performances are investigated in detail for an end-pumped structure. The calculation results reveal that the proper length of a Ho3+:BaY2F8 crystal is from 5 to 10 mm for the Ho3+ doping concentration of 10-40 at.%. We also deduce that a high output can be obtained when the Ho3+ doping concentration is selected as 30 at.%. It has been demonstrated that the relaxation oscillation of a Ho:BYF laser can be observed for a pulsed pump source. We can see that the threshold peak power of a pump light source decreases with the increase of the pulse width. The conclusions might be useful for the realization of a pulsed mid-infrared Ho3+:BYF laser.
关键词： rate equations,mid-infrared laser,directly-pumped,Ho3+:BaY2F8
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Designing and Characterizing Metalenses for the Increased Light Extraction of MWIR LEDs
摘要： High radiance IRLEDs have been achieved, but much of the light created still remains in the device resulting in poor wall-plug efficiencies. Preliminary results presented here show increased light extraction by the addition of a 2D lens to the device, known as a metalens.
关键词： Mid-infrared LEDs,LED arrays
更新于2025-09-16 10:30:52
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[IEEE 2019 Thirteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Rome, Italy (2019.9.16-2019.9.21)] 2019 Thirteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Wide Band Polarization Converter Graphene Metasurface for Mid-Infrared Band
摘要： Wide band, insensitive incidence angle graphene metasurface for polarization conversion is introduced in this work. A high Polarization Conversion Ratio (PCR) is verified in Mid-Infrared band by using a graphene as an upper conductor for metasurface. The metasurface construction is composed of a single layer of graphene, which has a half ring slots with rectangular slot connecting between them while the whole shape is rotated with 45o. Silicon dioxide substrate is used with a metal backed ground. The simulation results of the proposed metasurface indicate that a linearly polarized incident wave is converted to a circular polarized one over more than one THz along the Mid-Infrared frequency band. PCR has a maximum value of approximately 98% at 1.45 THz. The polarization conversion ratio is studied for different angles of incidence, with stable value for a wide range of incident angles.
关键词： Insensitive incidence angle,Graphene metasurface,Wide band,Mid-Infrared band,Polarization Conversion Ratio (PCR)
更新于2025-09-16 10:30:52
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An ultra-stable 2.9 μm guided-wave chip laser and application to nano-spectroscopy
摘要： 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 M2 x,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.
关键词： ultra-stable,continuous-wave laser emission,guided-wave chip laser,nano-spectroscopy,mid-infrared
更新于2025-09-16 10:30:52