- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[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) - Electro-Optic Frequency Comb Generation in Lithium Niobate Whispering Gallery Mode Resonators
摘要： Optical frequency combs (OFCs) are light sources whose spectra consists of equally spaced frequency lines in the optical domain [1]. They have great potential for improving high-capacity data transfer, all-optical atomic clocks, spectroscopy, and high-precision measurements [2]. In contrast to the traditional third-order nonlinearity based OFC generation methods, we present a new approach which is based on second-order non-linear effects in a whispering gallery mode (WGM) resonator made of lithium niobate (LN) [3,4]. Our system is composed of a resonant hybrid structure comprising an optical LN disk resonator and a microwave copper cavity. The hybrid structure enables highly efficient nonlinear mixing of photons. In this scheme, two continuous waves, one in the optical domain ((cid:2033) = 193 THz) and another in the microwave region (Ω = 8.9 GHz) couple within a LN WGM resonator [5]. The second-order non-linearity of LN leads to frequency comb generation via cascaded symmetric sum and difference frequency generation [6]. In our experiment, the optical pump power is coupled into the WGM by using a standard prism coupling method that is based on frustrated total internal reflection (Fig. 1 (a)). The microwave power is coupled using a coaxial probe coupled attached to the 3-D copper cavity specifically designed to have the microwave cavity resonance to be equal to the optical free spectral range of the LN resonator, required for efficient phase matching. In addition, the cavity design also provides a very good spatial overlap between the microwave and optical modes by confining the microwave field to the rim of the LN disk. In our proof-of-concept experimental demonstration we observe a 1.6 THz long frequency comb centred around 193.5 THz more than180 comb lines by using only 20 dBm of microwave power. Compared to previously reported OFCs generation schemes, this method has two major advantages: inherent phase stability, and better power efficiency. The power efficiency when measured in terms of pi-voltage of the modulator is 25 times better than a commercial Thorlabs modulator.
关键词： second-order non-linearity,whispering gallery mode resonators,electro-optic frequency comb generation,Optical frequency combs,lithium niobate
更新于2025-09-12 10:27:22
-
Generation of Frequency Combs by Quantum Cascade Lasers Emitting in the 8-μm Wavelength Range
摘要： We have studied the generation of frequency combs by quantum cascade lasers (QCLs) emitting in the 8-μm wavelength range. Results showed the presence of a self-pulsation regime near the lasing threshold. Further increase in the pumping current led to a sharp increase in width of the lasing spectrum, which allowed us to obtain frequency combs with a spectral width exceeding 1.5 THz. This behavior of QCLs can be explained by radiation absorption at the stripe edge that is related to the penetration of waveguide mode into unpumped regions.
关键词： quantum cascade laser,mode locking,Q-switching,frequency comb
更新于2025-09-12 10:27:22
-
[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) - Optical Frequency Comb Photoacoustic Spectroscopy
摘要： Photoacoustic spectroscopy (PAS) based on continuous wave (cw) lasers provides high absorption sensitivity in small sample volume [1, 2] but it is usually restricted to single species detection because of the limited tunability of cw lasers. Broadband PAS has been demonstrated using cantilever-enhanced detectors in combination with incoherent [3] or supercontinuum [4] light sources modulated by conventional Fourier transform spectrometers (FTS), however, the spectral resolution was limited to a few cm-1. Here we report the first demonstration of optical frequency comb photoacoustic spectroscopy (OFC-PAS), which combines the wide spectral coverage and high resolution of frequency combs with the small sample volume of photoacoustic detection [5]. The OFC-PAS setup is based on a doubly-resonant optical parametric oscillator pumped by a femtosecond Tm:fiber laser with a repetition rate of 125 MHz. The intensity of the signal output centered at 3.3 μm is modulated at ~500 Hz using an FTS. One output of the FTS (4.8 mW of signal power) is directed to a 10-cm-long cantilever-enhanced photoacoustic cell with 8 mL volume (Gasera, PA201), while the other is measured with a photodetector and used for normalization of the PA spectrum. Figure 1(a) shows in red the room temperature OFC-PAS spectrum of the C-H stretch band of 100 ppm of CH4 in N2 at 1000 mbar and 1 GHz resolution (left axis) recorded in 200 s (no averaging). The blue curve shows the simulated absorption coefficient, (cid:68), based on the parameters from the HITRAN database (right axis). A zoom-in around the Q-branch region at 1000 mbar and 400 mbar is shown in Figs 1(b) and 1(c), demonstrating the high spectral resolution, no instrumental lineshape distortion, and good agreement with the simulation. The limit of detection (LOD), evaluated from the signal to noise ratio of the methane line at 3058 cm-1 at 1000 mbar, is 0.8 ppm in 200 s for power spectral density of 42 μW/cm-1. While this LOD is comparable to those obtained with other broadband PAS methods [3, 4], the resolution of OFC-PAS is more than two orders of magnitude better. The normalized noise equivalent absorption at 1000 mbar is 8 × 10-10 W cm-1 Hz -1/2, comparable to values reported with PAS based on cw lasers [2]. OFC-PAS thus extends the capability of optical sensors for high-resolution multicomponent trace gas analysis in small sample volumes.
关键词： high-resolution spectroscopy,optical frequency comb,trace gas analysis,Photoacoustic spectroscopy
更新于2025-09-12 10:27:22
-
Broadband visible-near infrared and deep ultraviolet generation by four-wave mixing and high-order stimulated Raman scattering from the hybrid metasurfaces of plasmonic nanoantennae and Raman-active nanoparticles
摘要： The efficient generation of a broadband frequency comb from the visible to ultraviolet region is a challenging task despite its importance for nanoscale spectroscopy and sensing applications. In this paper, we reported broadband visible-near infrared and deep ultraviolet generation by four-wave mixing and high-order stimulated Raman scattering from hybrid metasurfaces made of plasmonic nanoantennae embedded with Raman-active diamond nanoparticles as examples. Upon two-color near-infrared pumping tuned to a Raman resonance, one can generate a visible-near infrared frequency comb with a major contribution of high-order stimulated Raman scattering by the coherent modulation of the Raman medium and simultaneously, a broad deep ultraviolet frequency comb is radiated by four-wave mixing and third-harmonic generations. The efficiencies of the individual spectral peaks reached values in the order of 10?8–10?2% under pumping with pulses with a peak intensity of about 33 GW cm?2 and a duration of 100 fs in the near infrared region.
关键词： high-order stimulated Raman scattering,visible-near infrared,hybrid metasurfaces,plasmonic nanoantennae,Raman-active diamond nanoparticles,deep ultraviolet,broadband frequency comb,four-wave mixing
更新于2025-09-12 10:27:22
-
[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) - Analysis of Optical Frequency Comb Generation in Gain-Switched Semiconductor Lasers
摘要： An Optical Frequency Comb (OFC) Generator is a laser source emitting an equally spaced group of optical tones. These types of optical sources have found application in different fields, such as spectroscopy [1] and optical communications [2]. Among the three main techniques for generating OFCs from semiconductor lasers, namely gain switching, electro-optic modulation and mode-locking, gain switching (GS) has attracted attention due to the simple selection of the repetition frequency and its easy implementation and low cost. We present here an exhaustive and systematic comparative analysis of the OFC generation using GS in semiconductor lasers. We have used a theoretical model, based on three stochastic differential equations that include non-linear saturation and Langevin noises, in order to simulate the experimental results. The experimental and simulated response has been studied in order to identify the main physical processes involved in the generation of GS OFC. An experimental characterization, based on RIN spectra measurements [5], was used to extract the parameters of the model. The OFC generator consists on a Discrete Mode Laser (DML), which is driven in GS operation using a bias current and a sinusoidal signal. High-resolution spectra were measured with a Brillouin Optical Spectrum Analyzer (BOSA).
关键词： Optical Frequency Comb,Spectroscopy,Optical Communications,Semiconductor Lasers,Gain Switching
更新于2025-09-12 10:27:22
-
[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) - Self-Injected Optical Frequency Comb Quantum Dash Lasers
摘要： Self mode-locked (SML) quantum dash (QDh) lasers emitting at around 1550 nm are compact broadband optical frequency comb (OFC) sources for multi-wavelength communication applications [1,2]. Optical self-feedback (OFB) by auxiliary cavities with lengths in the meter-range is a well-established method for a precise and dynamical mode spacing control of passively mode-locked (PML) semiconductor lasers. Recent works focused on identifying maximum tuning ranges of quantum well PML lasers and suggested that external OFB length, interaction width of fed-back pulse with the pulse inside the laser cavity and the OFB strength appear predominant [3]. In this contribution, we experimentally investigate and explain by modeling the dependence of mode spacing of OFB of SML QDh lasers subject to different cavity lengths on the external optical delay. Here, we study the impact of different OFB strengths and external OFB cavity lengths onto the mode spacing of QDh SML lasers. The three lasers investigated are 1 mm and 2 mm long, corresponding to a mode spacing of 40 GHz and 20 GHz, base on 6 and 9 layers of InAs/InGaAsP Qdhs [1,4] and exhibit as-cleaved facets. In the developed experimental set-up, sketched in Fig. 1a), the laser light is coupled into a lensed single-mode fiber and a part of the light is directed to the hybrid fiber based and free-space OFB cavity.
关键词： mode spacing control,optical frequency comb,self mode-locked,optical self-feedback,quantum dash lasers
更新于2025-09-12 10:27:22
-
[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) - Development of an XUV Frequency Comb for Precision Spectroscopy of Highly Charged Ions
摘要： Highly charged ions (HCI) have a few tightly bound electrons and many interesting properties for probing fundamental physics and developing new frequency standards [1, 2]. Many optical transitions of HCI are located in the extreme ultraviolet (XUV) and conventional light sources do not allow to study these transistions with highest precision. For this reason, we are developing an XUV frequency comb by transfering the coherence and stability of a near infrared frequency comb to the XUV by means of high-harmonic generation (HHG) [3-4]. Reaching intensity levels necessary for HHG (～ 1013W/cm2), while operating at high repetition rates (100 MHz) for large comb line spacing, is challenging. Therefore, the laser pulses are ?rst ampli?ed in a rod-type ?ber to 70 W and compressed to sub-200 fs in a grating and prism compressor. Afterwards, pulses are resonantly overlapped in an astigmatism-compensated femtosecond enhancement cavity, which is locked to the frequency comb. To achieve high stability and low-noise performance, the cavity is built on a rigid titanium structure with vibrational decoupling from the vacuum pumps. High-harmonics will then be generated in a target gas in the tight focus of the cavity and coupled out of the cavity by minus-?rst order diffraction from a small-period grating etched into a high-re?ective cavity mirror [5]. Mirror degradation due to contamination and hydrocarbon aggregation is prevented by operating the whole cavity under ultra-high vacuum conditions. A differential pumping scheme will enable high target gas pressures in the laser focus without impairing the pressure elsewhere in the chamber [6]. Finally, the XUV light will be guided to trapped and sympathetically cooled HCI [7] in a cryogenic superconducting linear Paul trap to drive narrow transitions with individual comb lines. A schematic overview of the experiment is shown in Fig. 1. Recent progress and ?rst experiments with intra-cavity multiphoton ionization are presented.
关键词： femtosecond enhancement cavity,highly charged ions,precision spectroscopy,high-harmonic generation,XUV frequency comb
更新于2025-09-12 10:27:22
-
[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) - Retrieving the Phase Relation of a Quantum Cascade Laser Frequency Comb and Reconstructing its Emission Profile
摘要： In the direction of miniaturizing and expanding optical frequency comb (FC) operation in the infrared (IR), the most relevant results have recently been achieved with quantum cascade lasers (QCLs) [1–4]. By using broadband Fabry-P′erot QCLs [5] designed to have a low group velocity dispersion, FC generation was demonstrated in fully free-running operation (QCL-combs) [6,7]. Various techniques to characterize the emission of mid- and far-infrared QCL-combs have been recently developed [6, 8–12]. Here we demonstrate the possibility of monitoring the Fourier phases of the modes of a FC (sample FC). The proposed approach bases on dual-comb multi-heterodyne detection using a metrological FC as reference (LO-FC) and a subsequent Fourier transform analysis (see ?g. 1a), allowing a simultaneous retrieval of the modes phases (?g. 1b). The required stability is obtained by post-detection RF common frequency noise suppression. This approach is the most direct method for FCs characterization, being suitable for IR FCs. A mid-IR and a THz QCL-comb (sample FCs) have been characterized. As LO-FCs two difference-frequency-generated FCs have been used. The measurements consisted in series of seven consecutive acquisitions. A strong correlation among the modes and a remarkable phase stability over 10s of minutes have been evidenced (see ?g. 1c). For the THz QCL-comb all the emitted modes can be acquired, therefore it is possible to reconstruct the emission pro?le and the instantaneous frequency (?g. 1d and e), con?rming a substantial deviation with respect to typical FC pulsed operation. The observed standard deviations on the obtained phases are in the order of 8 ? 10° at tens-of-minutes timescale. Concerning the phase relation, the scattering of THz QCL-comb phases (Fourier phases) encompasses a range of 300°, a value which cannot be associated to short-pulses operation. The quadratic term found in the phase relation (?g. 1b) can be attributed to chirping in QCL-comb emission. The reconstructed emission pro?les are roughly the same from measurement to measurement over the 30 minutes. Noticeably, the QCL-comb emission deviates from a pulsed emission, even though its amplitude is deeply modulated during the round trip. The obtained instantaneous frequency con?rms that the THz QCL-comb operates in a hybrid amplitude-/frequency-modulated regime. The gained knowledge of the phase relation provides the basis for future implementation of programmable pulse shaping. The remarkable phase stability attained for the QCL-combs modes conclusively proves the high coherence characterizing their emission, demonstrating that these sources are potentially suitable for metrological applications.
关键词： Fourier phases,frequency comb,quantum cascade laser,dual-comb multi-heterodyne detection,metrological applications
更新于2025-09-11 14:15:04
-
[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) - Frequency Comb Generation at 2 μm with Electro-Optic Modulators for Spectroscopic Applications
摘要： Mid-infrared (2–20 μm) gas sensing allows the detection of strong molecular absorptions with rather small absorption lengths (≤1 m). Various techniques can perform spectroscopic measurements in the mid-infrared but dual-comb spectroscopy (DCS) is one of the most powerful knowing its precision and real-time abilities [1]. However, setups used to perform DCS are in general complex since they require the phase locking of two independent femtosecond lasers at the known state of the art stability. This particular drawback can be bypassed if the combs are generated with electro-optic modulators (EOM) [2]. However, these equipments operate in the telecommunication wavelengths, generally near 1.55 μm where molecular absorptions are not very intense. Here, we experimentally demonstrate two different techniques of generating frequency combs with EOMs around 2 μm.
关键词： Spectroscopic applications,Frequency comb generation,Mid-infrared,Electro-optic modulators,Dual-comb spectroscopy
更新于2025-09-11 14:15:04
-
Precision locking CW laser to ultrastable optical frequency comb by feed-forward method
摘要： We locked a 1064 nm continuous wave (CW) laser to a Yb:fiber optical frequency comb stabilized to an ultrastable 972 nm CW laser with the feed-forward method. Consequently, the stability and coherent properties of the ultrastable laser are precisely transferred to the 1064 nm CW laser through the frequency comb’s connection. The relative linewidth of the frequency-stabilized 1064 nm CW laser is narrowed to 1.14 mHz, and the stability reaches 1.5 × 10?17/s at the optical wavelength of 1064 nm. The phase noise characterization in the 1 mHz–10 MHz range is presented to indicate that feed-forward locking a CW laser to an ultrastable comb will offer a potential technique for many important applications, such as optical frequency synthesis and gravitational wave detection.
关键词： feed-forward method,continuous wave laser,phase noise,frequency stability,optical frequency comb
更新于2025-09-11 14:15:04