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Transmission characteristics of 24.5??Gb/s atmospheric laser communication based on optical frequency comb
摘要： Through cascading Mach–Zehnder intensity modulator (MZIM) and phase modulator (PM), an optical frequency comb (OFC) with 7 flat comb teeth is produced. The frequency interval of the OFC is 25 GHz and the flatness is less than 1.5 dB. The 7 channels of the OFC are used as the carrier source of the one-to-many free-space optical (FSO) communication system, and the atmospheric turbulence simulation pool is used to simulate the turbulence intensity in the real atmosphere to verify its feasibility for FSO communication. In the experiment, the bit error rate (BER) and eye diagram are measured under the back-to-back (BTB) conditions, and the temperature difference of atmospheric turbulence simulation pool are 80 ?C, 150 ?C and 220 ?C. Each channel of the system can stably transmit the on–off keying (OOK) signal of 3.5 Gb/s, and the 7 channels can stably transmit the OOK signal of 24.5 Gb/s. Thereby, the OFC can be used in place of multiple lasers or laser arrays as a carrier source for a one-to-many FSO communication system.
关键词： Wavelength division multiplexing,Optical frequency comb,Atmospheric turbulence,Free-space optical communication
更新于2025-09-23 15:19:57
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Ultra-Wide and Flattened Optical Frequency Comb Generation Based on Cascaded Phase Modulator and LiNbO3-MZM Offering Terahertz Bandwidth
摘要： In this paper, a new technique for generation of ultra-wide and flattened optical frequency comb (OFC) based on serial cascading of a phase modulator and dual-driven Lithium-Niobate Mach Zehnder modulator (DD-LiNbO3-MZM) is proposed. Over 60 carriers were generated by carefully adjusting the RF switching voltage (RFSV) of the DD-LiNbO3-MZM and the signal frequency of the sinusoidal wave (RF) source. A low power amplified RF source with a signal driving power of ~16.9dBm is applied, and the power of CW laser is kept at 3dBm. The frequency spacing (FS) is kept at 20GHz for generating the maximum number of carriers. Nonetheless, the scheme is also tested for the FSs of 64GHz, and 32GHz. Each scenario is examined in simulation environment and the main outcomes are highlighted. The proposed scheme is comparatively simple and the FS varies with the applied RF source on the modulators. The achieved OFC lines have a tone-to-noise ratio (TNR) of over ~45dB with an undesired side mode suppression ratio of approximately 20dB. The comb lines are almost flat with a varying power deviation of around 0dB-6dB which is optimized to nearly ~0.12dB. Furthermore, the impact of the RFSV on the generated number of carriers is studied in detail. The scheme is analyzed in terms of cost efficiency, power deviations, TNR, optical signal to noise ratio, and number of achieved comb lines.
关键词： Optical Frequency Comb,Mach-Zehnder modulator,Phase modulator,Intensity modulation
更新于2025-09-23 15:19:57
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Photon-driven broadband emission and frequency comb RF injection locking in THz quantum cascade lasers
摘要： We present homogeneous quantum cascade lasers (QCLs) emitting around 3 THz which display bandwidths up to 950 GHz with a single stable beatnote. Devices are spontaneously operating in a harmonic comb state, and when in a dense mode regime they can be injection locked at the cavity roundtrip frequency with very small RF powers down to -55 dBm. When operated in the electrically unstable region of negative differential resistance, the device displays ultra-broadband operation exceeding 1.83 THz (?f /f = 50%) with high phase noise, exhibiting self-sustained, periodic voltage oscillations. The low CW threshold (115 A· cm?2) and broadband comb operation (?f /f = 25%) make these sources extremely appealing for on-chip frequency comb applications.
关键词： quantum cascade laser,terahertz,domain formation,injection locking,frequency comb
更新于2025-09-23 15:19:57
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Single-photon superradiance in waveguide-quantum-electrodynamical systems with whispering-gallery-mode resonators
摘要： As a manifestation of cooperative interactions between a single photon and a cluster of atoms, single-photon superradiance has attracted considerable attention recently but has been studied insofar as that only quantum emitters are involved in the superradiance process. Here we expand the scope of investigation to study single-photon superradiance in a waveguide-quantum-electrodynamical system containing whispering-gallery-mode (WGM) resonators which are essential for many nanophotonic devices. It is shown analytically and numerically that single-photon superradiance can also occur when WGM resonators are present. The criteria for the emergence of the superradiant emission peak and the enhanced atom-light coupling strength are derived. Finally, the general case of a cascade of WGM resonators is investigated by a renormalization approach. Single-photon frequency comb generation is demonstrated via a frequency-modulated superradiant effective atom in chiral waveguide-quantum-electrodynamical systems with WGM resonators.
关键词： single-photon superradiance,whispering-gallery-mode resonators,atom-light coupling,waveguide-quantum-electrodynamical systems,frequency comb generation
更新于2025-09-23 15:19:57
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Polarization-dependent High Quality Optical Frequency Comb Generator Based on Recirculating Frequency Shift
摘要： A polarization-dependent optical frequency comb (OFC) generation scheme based on recirculating frequency shift (RFS) is proposed and demonstrated. A dual-parallel Mach-Zehnder modulator (DPMZM) is employed to perform the carrier suppressed single sideband (CS-SSB) modulation and a polarization modulator (PolM) is adopted to generate a 5-line OFC. They are working in two orthogonal polarizations, respectively. The simulation results show that the proposed scheme can generate a 120-line OFC with flatness of 3.91 dB.
关键词： recirculating frequency shift (RFS),optical frequency comb (OFC),flatness,carrier suppressed single sideband modulation (CS-SSB)
更新于2025-09-19 17:15:36
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Numerical study of comb-based high-accuracy distance measurement utilizing VIPA interferometry
摘要： The ultrahigh-precision distance measurement based on a single laser frequency comb as the multi-wavelength source together with an ultra-high-resolution dispersive spectrometer utilizing a virtually imaged phase array (VIPA) was studied numerically. The simulations provide the component parameter optimization and the comb spectral images on a CCD camera. An ameliorated scheme was proposed through achieving real-time comparisons between the reference and interference signals captured on a camera simultaneously to improve both the measurement accuracy and the precision signi?cantly. With the optimized data processing, the proposed approach is especially suitable for serving as a ultra-high precision relative distance measurement, and the measurement resolution can reach picometer scale in the optimal cases.
关键词： Ultra-high precision distance measurement,Ultra-high resolution spectroscopy,Laser frequency comb,Virtually imaged phase array interferometry
更新于2025-09-19 17:15:36
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Photonics-based Multiband Radar Applying an Optical Frequency Sweeping Comb and Photonic Dechirp Receiving
摘要： A photonics-based multiband radar is proposed based on an optical frequency sweeping comb and photonic dechirp receiving. The proposed radar has a simple structure, and it is capable to simultaneously generate and process multiple in different frequency bands. Besides, the radar receiver can achieve fast or real-time signal processing with low-speed electronics. In the proof-of-concept experiment, a photonics-based dual-band radar working in K-band (19-22 GHz) and Ka-band (34-37 GHz) is demonstrated with a bandwidth of 3 GHz in each band and a sampling rate of 100 MSa/s in the receiver.
关键词： dechirp processing,multiband radar,optical frequency comb,microwave photonics
更新于2025-09-19 17:15:36
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Optical frequency comb generation with low temperature reactive sputtered silicon nitride waveguides
摘要： Integrated silicon nitride (SiN) waveguides with anomalous dispersion have the potential to bring practical nonlinear optics to mainstream photonic integrated circuits. However, high-stress and high-processing temperatures remain an obstacle to mass adoption. We report low-stress, high-confinement, dispersion-engineered SiN waveguides utilizing low temperature grown reactive sputtered thin-films. We demonstrate a microring resonator with an intrinsic quality factor of 6.6 × 105, which enabled us to generate a native free spectral range spaced frequency comb with an estimated on-chip pump power of 850 mW. Importantly, the peak processing temperature is 400 ○C making this approach fully back-end compatible for hybrid integration with preprocessed CMOS substrates and temperature sensitive photonic platforms such as lithium niobate on insulator.
关键词： reactive sputtering,optical frequency comb,silicon nitride waveguides,photonic integrated circuits,nonlinear optics
更新于2025-09-19 17:13:59
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Microsecond Resolved Infrared Spectroelectrochemistry Using Dual Frequency Comb IR Lasers
摘要： A dual infrared frequency comb spectrometer with heterodyne detection has been used to perform time resolved electrochemical attenuated total reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). The measurement of the potential dependent desorption of a monolayer of a pyridine derivative (4-dimethylaminopyridine, DMAP) with time resolution as high as 4 μs was achieved without the use of step-scan interferometry. An analysis of the detection limit of the method as a function of both time resolution and measurement co-additions is provided and compared to step-scan experiments of an equivalent system. Dual frequency comb spectroscopy is shown to be highly amenable to time-resolved ATR-SEIRAS. Microsecond resolved spectra can be obtained with high spectral resolution and fractional monolayer detection limits in a total experimental duration that is two orders of magnitude less than the equivalent step-scan experiment.
关键词： 4-dimethyamino pyridine (DMAP),noise analysis,Dual frequency comb spectroscopy,time resolved spectroelectrochemistry,RC constant,attenuated total reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS),detection limit
更新于2025-09-19 17:13:59
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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) - Impact of Nonlinearity on RF-Modulated Frequency Combs with Different Modulation Depths in an MUTC Photodetector
摘要： We calculate the impact of nonlinearity in a modi?ed uni-traveling carrier (MUTC) photodetector on an RF-modulated frequency comb that is generated using short optical pulses. We take into account bleaching (nonlinear saturation), which plays an important role due to the large peak-to-average power ratio. Nonlinear impairment of an RF-modulated continuous wave is characterized by the second- and third-order intermodulation distortion (IMD2 and IMD3). By contrast, an RF-modulated frequency comb is characterized by a distinct IMD2n and IMD3n for each comb line n. We study the effect of modulation depth on nonlinearity in frequency combs, comparing modulation depths of 4% and 8%. When we include bleaching, we ?nd that the OIP3n, third-order intercept point for the n-th comb line, increases when the modulation depth increases for comb lines at frequencies above 2 GHz (n (cid:2) 40), so that distortion decreases. We show that this effect occurs because bleaching attenuates lower frequencies more than higher frequencies and this preferential attenuation increases as the modulation depth increases.
关键词： MUTC,IMD2,IMD3,frequency comb,nonlinearity,bleaching
更新于2025-09-19 17:13:59