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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) - 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
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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) - 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
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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
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A Multiband Transparent Transponder Based on Reconfigurable Optical Frequency Combs for Cross Connection of Intersatellite and Satellite Ground
摘要： In this paper, a parallel multiband frequency-conversion scheme for satellite applications based on a single optical frequency comb is proposed, and a recon?gurable satellite transponder is designed for future multiband broadband satellites. In addition, we establish a test system of onboard multiband frequency-conversion on the strength of microwave photonics and, a proof-of-concept experiment is demonstrated in which a Ka-band signal is converted to other satellite frequency bands. The experimental results reveal our system feasibility, and the bit error rate of recovered baseband data is less than 10–9. Moreover, the optical frequency combs can be recon?gured by adjusting the parameters of the local oscillator and optical modulator.
关键词： multi-band frequency conversion,Microwave photonics,recon?gurable satellite transponder.,optical frequency comb
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - On-Chip Optical Frequency Comb Generation for RF Photonic Applications
摘要： We review several key problems in microresonator frequency comb generation for RF photonic applications, including comb intensity noise and power conversion efficiency, and show some preliminary demonstrations based on mode-locked and low-noise Kerr combs including programmable complex-tap signal processing and true-time-delay beamforming.
关键词： RF photonic applications,low-noise,mode-locked,optical frequency comb,Kerr comb,microresonator
更新于2025-09-09 09:28:46