A5061843125- Spectroscopy and Laser Applications
- Laser Design and Applications
- Atmospheric Ozone and Climate
- Semiconductor Lasers and Optical Devices
- Atmospheric and Environmental Gas Dynamics
- Photonic and Optical Devices
- Advanced Fiber Laser Technologies
- Spectroscopy and Chemometric Analyses
- Spectroscopy Techniques in Biomedical and Chemical Research
- Analytical Chemistry and Sensors
- Advanced Chemical Sensor Technologies
- Optical Imaging and Spectroscopy Techniques
- Coronary Interventions and Diagnostics
- Gas Sensing Nanomaterials and Sensors
- Solid State Laser Technologies
- Mechanical and Optical Resonators
- Peripheral Artery Disease Management
- Semiconductor Quantum Structures and Devices
- Laser-Matter Interactions and Applications
- Phase Equilibria and Thermodynamics
- Ocular and Laser Science Research
- Mass Spectrometry Techniques and Applications
- Air Quality Monitoring and Forecasting
- Chemistry and Stereochemistry Studies
- Cerebrovascular and Carotid Artery Diseases
Hamamatsu Photonics (Japan)
2014-2024
Hamamatsu Photonics (United Kingdom)
2008-2020
Hamamatsu Medical Center
2019
Central Research Laboratories (United Kingdom)
2008
Ritsumeikan University
2008
High-sensitivity radiocarbon detection has been, until now, a prerogative of accelerator mass spectrometry (AMS). Here we present compact and simple spectroscopic apparatus, based on saturated-absorption cavity ring-down, approaching the ultimate AMS sensitivity. We measure dioxide concentration down to few parts per quadrillion by use heterodyne-spectroscopy system with two quantum cascade lasers at 4.5 μm, reference cell, high-finesse sample gas cooled 170 K. Our results pave way paradigm...
We report on a spectroscopic technique named intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) employed for sensitive trace-gas detection in the mid-infrared spectral region. It is based combination of QEPAS with buildup optical cavity. The sensor includes distributed feedback quantum cascade laser emitting at 4.33 μm. achieved power factor ∼500, which corresponds to an ∼0.75 W. CO2 has been selected as target molecule I-QEPAS demonstration. sensitivity 300 parts per trillion...
We have developed a theory of the intrinsic linewidths laser output single-mode quantum-cascade (QC) lasers in mid-infrared and terahertz (THz) ranges. In theoretical treatment, concept an effective coupling efficiency spontaneous emission, given by fractional rate emission coupled into lasing mode to total nonlasing relaxation, is introduced clarify hidden reason for narrowness linewidths. A narrow linewidth (12-kHz) reported with frequency-stabilized 8.5- distributed-feedback QC...
The frequency-noise power spectral density of a room-temperature distributed-feedback quantum cascade laser emitting at λ = 4.36 μm has been measured. An intrinsic linewidth value 260 Hz is retrieved, in reasonable agreement with theoretical calculations. A noise reduction about factor 200 most the frequency interval also found, respect to cryogenic same wavelength. quantitative treatment shows that it can be explained by temperature-dependent mechanism governing transport processes resonant...
We report on the narrowing of a room-temperature mid-IR quantum cascade laser by frequency locking it to CO2 sub-Doppler transition obtained polarization spectroscopy. A bandwidth 250 kHz has been achieved. The linewidth is narrowed more than two orders magnitude below 1 kHz, and its absolute stabilized at same level.
We report on the linewidth narrowing of a room-temperature mid-infrared quantum cascade laser by phase-locking to difference-frequency-generated radiation referenced an optical frequency comb synthesizer. A locking bandwidth 250 kHz, with residual rms phase-noise 0.56 rad, has been achieved. The is narrowed more than 2 orders magnitude below 1 and its stabilized absolute traceability 2×10−12. This source allowed measurement CO2 molecular transition uncertainty about kHz.
An ultra-sensitive and selective quartz-enhanced photoacoustic spectroscopy (QEPAS) combined with a high-finesse cavity sensor platform is proposed as novel method for trace gas sensing. We call this technique Intra-cavity QEPAS (I-QEPAS). In the scheme, single-mode continuous wave quantum cascade laser (QCL) coupled into bow-tie optical cavity. The locked to QCL emission frequency by means of feedback-locking loop that acts directly on piezoelectric actuator mounted behind one mirrors. A...
Narrow‐linewidth lasers are key elements in optical metrology and spectroscopy. Spectral purity of these determines accuracy the measurements quality collected data. Solid state fiber stabilized to relatively large complex external cavities or narrow atomic molecular transitions improve their spectral purity. While this stabilization technique is rather generic, its complexity increases tremendously moving longer wavelenghts, infrared (IR) range. Inherent increase losses materials at...
We report on the experimental demonstration of metrological and spectroscopic performances a mid-infrared comb generated by nonlinear downconversion process from Ti:sapphire-based near-infrared comb. A quantum cascade laser at 4330 nm was phase-locked to single tooth this its frequency-noise power spectral density measured. The itself also used as multifrequency highly coherent source perform ambient air direct spectroscopy with Vernier technique, demultiplexing it high-finesse Fabry-Perot cavity.
A mid-infrared spectroscopic system using a high-speed wavelength-swept and pulsed quantum cascade laser (QCL) for healthcare applications such as blood glucose measurement is proposed. We developed an attenuated total reflection comprising the QCL with micro-electromechanical (MEMS)-scanning grating, hollow optical fibers, InAsSb detector tested its feasibility applications. continuous spectrum was obtained by integrating comb-shaped spectra, timing of which slightly shifted. As this method...
We propose a new quantum-cascade laser structure with single phonon resonance-continuum depopulation and demonstrate room temperature, continuous-wave operation of the proposed 7.9μm laser. The grown by metal organic vapor-phase epitaxy emits cw output power 36mW at 30°C, exhibiting threshold current density 2.23kA∕cm2. is reported for higher temperatures up to slightly above 60°C. may lead successful commercial mass production lasers.
We report high performance λ~8.6 μm m quantum cascade lasers based on 5 well single phonon-continuum (SPC) depopulation scheme, grown by metal organic vapor-phase epitaxy. Devices with SPC structures exhibit device performances in pulsed and continuous wave (CW) operation due to a large dipole matrix element (3.0 nm) short time (0.22 ps). A 4 mm-long, 8 μm-wide, reflective (HR)-coated buried-hetero-structure laser 33 stages, for active region, demonstrates output power of 313 mW, threshold...
The infrared spectrum of the (0111–0110) ro-vibrational band 12C16O2 in range 2306–2312 cm−1 is investigated with saturated-absorption sub-Doppler spectroscopy. absolute frequencies six transitions belonging to P-branch this are measured by recording their Lamb-dip features a pump-probe detection scheme employing room-temperature quantum cascade laser. laser phase-locked subkilohertz-linewidth difference-frequency-generated radiation source, which referenced an optical frequency comb...
A wide wavelength tuning of an external cavity quantum-cascade laser (QCL) based on the anticrossed dual-upper-state to multiple-lower-state design is demonstrated in continuous wave (cw) operation at room temperature. The ranges 321 cm-1 (Δλ/λ∼22%) pulsed and 248 (Δλ/λ∼17%) cw are achieved, despite employment active region with translational symmetry. present range substantially exceeds values obtained QCLs conventional broadband designs. In addition, continuous, single mode realized its...
The need for highly performing and stable methods mid-IR molecular sensing metrology pushes towards the development of more compact robust systems. Among innovative solutions aimed at answering references are crystalline microresonators, which have recently shown excellent capabilities frequency stabilization linewidth narrowing quantum cascade lasers with setups. In this work, we report on first system high-resolution spectroscopy based a laser locked to CaF2 microresonator. Electronic...
The linewidth enhancement factor of a 5μm distributed feedback (DFB) quantum cascade laser above the threshold current detuned from gain peak was investigated. This oscillates in two DFB modes located on either side peak. Using optical self-mixing method, we have observed variations factor, deviating zero. signs are both negative, which verified by comparing their waveforms with that conventional 1.55μm diodes, suggesting curve is asymmetric respect to
Broadband spectral tuning in the long wavelength range (greater than 10 μm) was demonstrated with an external-cavity quantum cascade laser. The tunable of laser ranged from 9.5 to 11.4 μm (176 cm(-1); corresponding 18% center wavelength) continuous wave (cw) operation at room temperature, without any anti-reflection coating. gain chip based on anti-crossed dual-upper-state (DAU) design provided a cw lasing up 300 K, low threshold current density 2.1 kA/cm2. highly stable broadband and high...
Molecules such as water, proteins and lipids that are contained in biological tissue absorb mid-infrared (MIR) light, which allows light to be used laser surgical treatment. Esters, amides water exhibit strong absorption bands the 5–7 μm wavelength range, but at present there no lasers clinical use can emit this range. Therefore, study focused on quantum cascade (QCL), is a new type of semiconductor MIR wavelengths has recently achieved high output power. A high-power QCL with peak 5.7 was...
Broadband, high-resolution, heterodyne, mid-infrared absorption spectroscopy was performed with a high-speed quantum cascade (QC) detector. By strictly reducing the device capacitance and inductance via air-bridge wiring small mesa structure, 3-dB frequency response over 20 GHz obtained for QC detector, which had 4.6-μm peak wavelength response. In addition to high-speed, it exhibited low noise characteristics limited only by Johnson–Nyquist noise, bias-free operation without cooling,...
We report the experimental linewidth enhancement factor (α-factor) results on mid-infrared InGaAs/InAlAs quantum cascade lasers (QCLs) obtained using self-mixing method. The waveforms appearing under conditions were different from those originally predicted, which assumed that gain was symmetric around peak and α=0. signs of QCL α-factors identified to be negative asymmetric by nonsymmetrical mirror drive, comparing their wave patterns conventional 1.55-µm laser diodes. nonparabolicity...
The magnitude of the relative intensity noise (RIN) a 5 µm distributed-feedback quantum cascade laser (DFB-QCL) was compared with conventional 1.55 DFB diode (LD). RIN for DFB-QCL at frequency 1 MHz –157 dBm 10 mW light output, about dB higher than that DFB-LD, which could almost be fully explained by semi-classical model. resonant tunnelling induced noise, might cause degradation, not observed.