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All-polarization-maintaining, semiconductor saturable absorbing mirror mode-locked femtosecond Er-doped fiber laser with a gigahertz fundamental repetition rate
摘要： A passively mode-locked fiber laser with a 1.03 GHz fundamental repetition rate and a low noise performance is demonstrated. The compact and robust laser operates at a central wavelength of 1553.9 nm with a 3 dB spectral bandwidth of 7.9 nm and a temporal width of 550 fs. All the fibers and components used in the laser are polarization-maintaining (PM), so the output pulses are linearly polarized. The degree of polarization of the optical pulses is measured to be 0.9994. The phase noise of the seventh harmonic (7.21 GHz) is measured and a low timing jitter of 11.7 fs is obtained by integrating the phase noise from 30 MHz down to 100 Hz. The noise performance is analyzed in detail, and the methods for further optimizing the timing jitter are also proposed. So far, we know this to be the first-reported low-noise all-PM erbium-doped fiber laser with a gigahertz level pulse repetition rate.
关键词： low-timing jitter,polarisation-maintaining (PM),high-pulse repetition rate
更新于2025-11-28 14:23:57
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Minimal Timing Jitter in Superconducting Nanowire Single-Photon Petectors
摘要： Using a two-temperature model coupled with the modified time-dependent Ginzburg-Landau equation, we calculate the delay time τd in the appearance of a growing normal domain in the current-biased superconducting strip after absorption of the single photon. We demonstrate that τd depends on the place in the strip where the photon is absorbed and monotonically decreases with an increasing current. We argue that the variation of τd (timing jitter), connected either with position-dependent response or Fano fluctuations, could be as small as the lowest relaxation time of the superconducting order parameter, approximately ?/kBTc (Tc is the critical temperature of the superconductor), when the current approaches the depairing current.
关键词： position-dependent response,timing jitter,superconducting nanowire single-photon detectors,delay time,Fano fluctuations
更新于2025-09-23 15:23:52
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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) - Pulse Timing and Amplitude Stability of a Monolithic Passively Mode-Locked Quantum Dot Laser at 1310 nm Directly Grown on Silicon
摘要： Passively mode-locked (PML) InAs/InGaAs quantum dot (QD) lasers directly grown on silicon and emitting at 1310 nm are promising sources for high-speed, high-capacity communication applications. To overcome the low light generation efficiency of silicon, QD are directly grown on Si [1]. Their ultrafast carrier dynamics, broadband gain spectra and easily saturated gain and absorption allow for the generation of ultra-short optical pulses as demonstrated very recently [2]. The QD laser epitaxial growth was completed on an on-axis (001) Si substrate with a 45 nm GaP buffer layer by solid-source molecular beam epitaxy [3]. In this contribution, the pulse train stability of a PML QD laser consisting of a five-stack InAs/InGaAs dots-in-a-well structure is experimentally studied. The total length of the laser was designed to be 4.5 mm with a saturable absorber length corresponding to 18 %. The isolation length between gain and absorber section is 10 μm. The laser emits optical pulse trains at a repetition rate (RR) of 9.4 GHz. Fig. 1a depicts the pulse-to-pulse timing jitter (TJ) σpt p = 0.5 [4] with Δν being the RR line width in the radio-frequency (RF) spectrum and ν0 being the RR. The TJ is calculated from the timing phase noise (TPN) power spectral densities (PSD) [5] in dependence on the absorber reverse bias voltage and the gain current. Low TJ values of around 100 fs to 200 fs can be identified in the majority of biasing regimes. In the regime for shortest pulses with pulse widths below 5 ps, located just above lasing threshold and at gain currents below 120 mA, very low TJ values (color coded purple) are obtained. A lowest TJ of 9 fs (-3 dB fundamental RR beat note line width of 400 Hz) is obtained at a gain current of 105 mA and an absorber reverse bias voltage of 0.6 V, slightly above lasing threshold. The corresponding TPN PSD is depicted in Fig. 1b. The optical pulse train amplitude jitter (AJ) is quantified as a relative standard deviation of the pulse intensity variations [6]. As indicated in Fig. 1c, an AJ below 5 % is attained in the short pulse regime which is located at gain currents below 120 mA and at higher currents and low saturable absorber voltages (color coded purple). Such low AJ denotes excellent stable operation. Fig. 1d depicts the nonlinear intensity auto-correlation signal representing the shortest deconvoluted pulse width of 1.7 ps at 125 mA and 2.6 V absorber reverse bias voltage. The corresponding time-bandwidth product amounts to 1.1. Pulses with pulse widths shorter than 10 ps where obtained at all biasing conditions except for high gain currents above 140 mA and small absorber reverse bias voltages below 0.6 V. In this small regime pulse widths of 10 ps to 18 ps are obtained. In conclusion, stable optical pulse train generation by a monolithic passively mode-locked InAs/InGaAs quantum dot laser directly grown on silicon with a lowest optical pulse width of 1.7 ps, a lowest timing jitter of 9 fs (400 Hz RR beat note line width) and a negligible relative amplitude jitter are experimentally reported.
关键词： timing jitter,silicon,quantum dot laser,amplitude jitter,mode-locked
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) - Operational Description of Single-Photon Detectors Including Timing-Jitter Effects
摘要： Discrete variable quantum optics stands as one of the most prominent platform for quantum technologies with an increasing number of encouraging out-of-the-laboratory implementations [1]. The quest for competitive quantum photonic systems, compatible with future engineered systems, has promoted huge developments concerning both source and detection devices [2]. To date, a critical point lies in experiments’ operation rates. Time multiplexing technics allow in principle to pump photonic sources at rates on the order of the GHz [3]. However, a strong limitation to ultra-fast operation lies in timing errors at the detection stage. Limited resolution directly affects the quality of any time-correlated single photon counting or quantum state engineering operations [3]. In particular, single photon detector’s timing-jitters lead counts associated with a given optical clock cycle to appear as temporally indistinguishable from those corresponding to neighbouring ones [2]. Fast and accurate time-tagging is mandatory in multiple operations, such as quantum teleportation [1], quantum state engineering [3] and quantum random number generation. In anticipation to further technological advances, as well as in the perspective of promoting novel conceptual developments on existing quantum communication protocols, it is thus of the utmost importance to correctly describe the effects of detectors’ timing performances. In our work, we explicitly address the problem of detection temporal uncertainties by means of an original theoretical model able to describe the temporal behaviour of standard single photon detectors, with no photon-number resolving abilities [2], affected by non negligible timing-jitter and in presence of dead-time [4]. We consider the case of standard ON/OFF detectors, say detectors with no photon-number resolving abilities [2], and we adopt the formalism of positive operator-valued measurements (POVM) [5]. This approach has already been employed to describe detector with photon-number resolving abilities and has been successfully used to experimentally investigate the characteristics of unknown single photon detectors [6]. Our model exploits a multi-mode formalism to describe temporal degrees of freedom to fully describe timing-resolution effects in ON/OFF detectors by a fully operational POVM description, taking into account the effect of dead-time and finite detection efficiency, without any a priori restriction on the number of photons impinging on the detector. We apply our results to the quantitative study of timing-jitter effects in some usual quantum optics experiments, such as direct photon detection, coincidence measurements, and heralded quantum state preparation. As an example, for a time correlation experiment, considering a source of simultaneous twin photons, our model allows expressing explicitly the delay probability density function. As another example, this fully quantum approach allows expressing the density matrix of a single-photon state obtained in a heralded single-photon generation experiment [3], by taking into account the imperfections of the heralding detector. In conclusion, we believe that our work fills a gap in the discussion on practical quantum technologies by providing a full operational POVM description of practical detection stages, with non negligible timing-jitter and in presence of dead-time. Although we mostly provide simple examples involving one or two photons impinging on the detectors, our formalism is capable of describing general experimental situations. We therefore think that these characteristics stand as a valuable help for a better comprehension of the timing-jitter effect in the perspective of developing ultra-fast quantum communication, including when detector’s timing-jitter is not negligible with respect to repetition period.
关键词： timing-jitter,quantum communication,POVM,quantum optics,single-photon detectors
更新于2025-09-16 10:30:52
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Repetition rate transitions and timing stability improvement in monolithic multi-section semiconductor lasers
摘要： We study numerically passive mode-locking (PML) dynamics in a 4 mm long multi-section semiconductor laser with interdigitated absorber placement. Using the simulation tool FreeTWM, we identify repetition rate (RR) transitions from fundamental to higher harmonic PML by gain current control. The calculated timing jitter (TJ) varies from 17 fs to 5000 fs with the lowest TJ observed at the third harmonic RR. The simulations are confirmed by experimental investigations of a multi-section quantum-dot laser having the same geometry as in the simulations. RR transitions from 10 GHz to 30 GHz and TJ between 3 fs and 1000 fs are observed.
关键词： Semiconductor Laser,Timing Jitter,Simulation,Passive Mode-Locking,FreeTWM,Repetition Rate
更新于2025-09-16 10:30:52
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Optical feedback stabilization of a self-mode-locked quantum dot laser
摘要： In this work, the impact of fine-delay tunable dual-cavity optical self-feedback (DC-OFB) on the pulse timing stability and pulse repetition rate (RR) frequency of a 1 mm long single-section self-mode-locked quantum-dot (QD) laser emitting at 1255 nm is studied experimentally and by simulation. By tuning both microscopic dual-cavity delay lengths, we find a maximum RR tuning range of 70 MHz. A two-fold periodic structure is apparent every 25 ps which corresponds to the internal round trip time of the laser. A timing jitter (TJ) reduction by a factor of 16 down to 3.5 fs is obtained. Simulation results reproduce the experimentally observed RR trends with a good qualitative and quantitative agreement.
关键词： quantum-dot laser,Self mode-locking,timing jitter,optical feedback,semiconductor laser,radio-frequency linewidth
更新于2025-09-16 10:30:52
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Passively mode-locked quantum dot laser subject to dual long cavity time-delayed optical feedback
摘要： In this contribution, we study experimentally the impact of two long external passive optical cavities on the repetition rate and timing jitter of a monolithic passively mode-locked InAs/InGaAs quantum dot laser. The dual cavity scheme allows to fully suppress feedback induced sidebands in the radio-frequency spectrum. By fine delay control of the optical self-feedback delay lengths, a repetition rate tunability of 9.4 MHz is achieved. The lowest repetition rate line width amounts to less than 50 Hz, corresponding to a timing jitter of 1.7 fs. We explain the experimentally observed timing jitter and repetition rate trends qualitatively by adapting a versatile simple time-domain model. Both experiment and simulations indicate the strongest pulse train timing jitter reduction at feedback lengths that yield the lowest repetition rate frequency deviation.
关键词： quantum-dot laser,timing jitter,Passive mode-locking,Optical feedback,semiconductor laser,radio-frequency linewidth
更新于2025-09-16 10:30:52
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Regenerative Talbot laser for generating tunable pulse train with a low phase noise
摘要： We propose and demonstrate an improved Talbot laser architecture incorporating a regenerative RF feedback loop. This architecture greatly enhances both amplitude and noise performances of the laser, while preserving the broadband tunability of its repetition rate. The phase noise power spectral density of the associated RF signal is found to be independent of the repetition rate. For a 4.9 GHz repetition rate, the timing jitter is as low as 54 fs (integrated between 10 kHz and 100 MHz offset frequency). This architecture paves the way towards tunable high performances coupled opto-electronic microwave oscillators.
关键词： Pulsed lasers,timing jitter,optoelectronic devices,phase noise
更新于2025-09-12 10:27:22