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Microcavity-based frequency combs, or ‘microcombs’1,2, have enabled many fundamental breakthroughs3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21 through the discovery of temporal cavity-solitons. These self-localized waves, described by the Lugiato–Lefever equation22, are sustained by a background of radiation usually containing 95% of the total power23. Simple methods for their efficient generation and control are currently being investigated to finally establish microcombs as out-of-the-lab tools24. Here, we demonstrate microcomb laser cavity-solitons. Laser cavity-solitons are intrinsically background-free and have underpinned key breakthroughs in semiconductor lasers22,25,26,27,28. By merging their properties with the physics of multimode systems29, we provide a new paradigm for soliton generation and control in microcavities. We demonstrate 50-nm-wide bright soliton combs induced at average powers more than one order of magnitude lower than the Lugiato–Lefever soliton power threshold22, measuring a mode efficiency of 75% versus the theoretical limit of 5% for bright Lugiato–Lefever solitons23. Finally, we can tune the repetition rate by well over a megahertz without any active feedback.

Microcombs are optical frequency combs based on microcavity resonators [1] . They find multiple applications, including metrology, spectroscopy, frequency synthesis, and optical communications. Temporal cavity solitons (TCS), the temporal counterpart of spatial cavity solitons [2] , have been shown to produce microcombs with optimal spectral features [1] and are well modeled by the Lugiato-Lefever equation in passive systems. High contrast TCS can be also obtained in active systems inclusive of laser gain [3] .

Turing patterns and solitons are a common occurrence in systems that are out of equilibrium. For example, they regulate the emergence of organised structures in biology and chemistry. In optics, the study of temporal Turing rolls and cavity-solitons in nonlinear micro-cavity resonators has been key to the understanding of optical frequency comb formation in these structures. Over a decade, the impact of microresonator-based approaches to generating frequency combs – so-called "Micro-combs or "Kerr combs" – has reached far beyond metrology applications. Here we summarise our theoretical and experimental results for solitons and Turing patterns in a system comprising a micro-resonator nested in an auxiliary fibre-gain cavity.

We theoretically present a design of self-starting operation of microcombs based on laser-cavity solitons in a system composed of a micro-resonator nested in and coupled to an amplifying laser cavity. We demonstrate that it is possible to engineer the modulational-instability gain of the system's zero state to allow the start-up with a well-defined number of robust solitons. The approach can be implemented by using the system parameters, such as the cavity length mismatch and the gain shape, to control the number and repetition rate of the generated solitons. Because the setting does not require saturation of the gain, the results offer an alternative to standard techniques that provide laser mode-locking., Comment: To be published in Optics Express

In an open nonlinear system, emergent complex structures are generally determined by a set of global parameters. Cavity-solitons are an example of such structures and, in their temporal form, have seeded the last decade of major developments in microresonator-based optical frequency combs. These optical pulses typically require complex procedures and external feedback to be induced and maintained. Recent progress has seen the microresonators directly embedded into a laser cavity [1] , [2] where it is possible to simply initiate cavity-soliton formation by increasing the laser-diode driving current [3] . Hybrid laser-microresonator schemes have been considered since 2012 [4] , and extremely efficient laser cavity-solitons have been experimentally and theoretically demonstrated in a laser microcomb [5] .

A cartographical study is conducted within the parameter space of a microresonator- filtered fiber laser. We identify a region in which solitons are spontaneously formed and maintained, and we investigate the effects which govern their emergence.

International audience; We summarize our results on the generation of temporal laser cavity-solitons in a system comprising an optical micro-cavity nested in a fiber laser. We will discuss their features, region of existence, potential and challenges ahead. Dissipative solitons are self-confined pulses which appear in driven and lossy systems when the phase dispersion is balanced by the nonlinear phase-shift. Ultrashort pulses generated by passive mode-locking lasers are a very important example of temporal dissipative solitons in optics. Temporal cavity-solitons [1,2,3] also belong to this class of pulses and have been instrumental in the development of optical frequency combs in nonlinear micro-cavities, or "micro-combs" [1]. Temporal cavity-solitons have been largely studied in a 'driven' configuration, where an external pumping source is resonantly coupled in the nonlinear micro-resonator to sustain and excite the solitary pulses. More recently, we demonstrated that it is possible to generate localised pulses in a configuration where the micro-cavity is inserted in a fiber laser loop, as described in Figure 1. In particular, we reported the observation of laser cavity-solitons [4], which have previously attracted large attention especially in spatial configurations, such as in semiconductor lasers [5]. By merging their properties with the physics of both micro-resonators and multi-mode systems, this scheme represents a fundamentally new paradigm for the generation, stabilisation and control of solitary optical pulses in micro-cavities. Fig. 1. Scheme of the nested, travelling-wave cavities configuration: a Kerr micro-resonator (green loop) is nested in an amplifying fibre-loop (black). The amplifying cavity comprises a gain fibre (erbium-ytterbium doped amplifier, EYDFA), a tuneable delay line with optical couplers (OC), polarising beam splitter (PBS), polarisation control and a band-pass filter (BPF). The output of the laser is monitored with an optical spectrum analyser (OSA), a second-harmonic non-collinear autocorrelator and an oscilloscope to measure the radio-frequency noise of the system. © 2 0 2 0 T h e Au t h o r (s)

Microcombs based on Turing patterns have been extensively studied in configurations that can be modelled by the Lugiato-Lefever equation. Typically, such schemes are implemented experimentally by resonant coupling of a continuous wave laser to a Kerr microcavity in order to generate highly coherent and robust waves. Here, we study the formation of such patterns in a system composed of a microresonator nested in an amplifying laser cavity, a scheme recently used to demonstrate laser cavity solitons with high optical efficiency and easy repetition rate control. Utilizing this concept, we study different regimes of Turing patterns, unveiling their formation dynamics and demonstrating their controllability and robustness. By conducting a comprehensive modulational instability study with a mean-field model of the system, we explain the pattern formation in terms of its evolution from background noise, paving the way towards complete self-starting operation. Our theoretical and experimental paper provides a clear pathway for repetition rate control of these waves over both fine (Megahertz) and large (Gigahertz) scales, featuring a fractional frequency nonuniformity better than 7 × 10−14 with a 100-ms time gate and without the need for active stabilization.

The stability of laser temporal cavity solitons in micro-ring cavities nested in an externally pumped fibre loop with gain is investigated. The crucial roles of group velocity mismatch and gain dispersion are identified.

We report the characterization of a balanced ultrafast photodetector. For this purpose, we use a recently developed time-domain laser-based vector network analyzer (VNA) to determine the common-mode rejection ratio (CMRR) of the device under test. This includes the frequency-domain response above the single-mode frequency of the coaxial connector. Although the balanced photodetector has a nominal bandwidth of 43 GHz, it generates voltage pulses with frequency components up to 180 GHz. We obtain a CMRR of better than 30 dB up to 70 GHz and better than 20 dB up to 110 GHz. The laser-based measurements are compared with the measurements using a digital sampling oscilloscope and with the frequency-domain measurements using a conventional VNA. We obtain good agreement between the three techniques with the laser-based method providing the largest measurement bandwidth, although it also constitutes the most complicated characterization setup.

Nanohybrid materials based on nanoparticles of the intrinsically microporous polymer PIM-1 and graphene oxide (GO) are prepared from aqueous dispersions with a re-precipitation method, resulting in the surface of the GO sheets being decorated with nanoparticles of PIM-1. The significant blueshift in fluorescence signals for the GO/PIM-1 nanohybrids indicates modification of the optoelectronic properties of the PIM-1 in the presence of the GO due to their strong interactions. The stiffening in the Raman G peak of GO (by nearly 6 cm^{-1}) further indicates p-doping of the GO in the presence of PIM. Kelvin probe force microscopy (KPFM) and electrochemical reduction measurements of the nanohybrids provide direct evidence for charge transfer between the PIM-1 nanoparticles and the GO nanosheets. These observations will be of importance for future applications of GO-PIM-1 nanohybrids as substrates and promoters in catalysis and sensing.

Micro-resonator-based frequency combs, or micro-combs, have gained considerable interest in recent years due to their many potential applications such as high-speed communication systems, spectroscopy and ultrafast optical clocks [1]. Most micro-combs systems are based on laser pumped optical parametric oscillation and are typically non-self-starting, requiring a well-defined warm-up strategy involving smart control [2]. An alternative approach to micro-combs is represented by the Filter-Driven Four-Wave Mixing (FD-FWM) laser [3–5], based on a nonlinear micro-resonator nested in a main amplifying fibre cavity. Although this system has demonstrated self-starting regimes, stable operation typically imposes a strict relation between the minimum free-spectral range (FSR) of the main-cavity and the Q-factor of the micro-resonator. The use of longer main-cavity fibre lengths (highly desirable for several positive features, such as a larger gain) results in unrecoverable unstable regimes, i.e. in super-mode instability, which arises from the existence of many oscillating main-cavity modes within each micro-resonator resonance.

We report on 'slow' pulsing dynamics in a silica resonator-based laser system: by nesting a high-Q rod-resonator inside an amplifying fiber cavity, we demonstrate that trains of microsecond pulses can be generated with repetition rates in the hundreds of kilohertz. We show that such pulses are produced with a period equivalent to several hundreds of laser cavity roundtrips via the interaction between the gain dynamics in the fiber cavity and the thermo-optical effects in the high-Q resonator. Experiments reveal that the pulsing properties can be controlled by adjusting the amplifying fiber cavity parameters. Our results, confirmed by numerical simulations, provide useful insights on the dynamical onset of complex self-organization phenomena in resonator-based laser systems where thermo-optical effects play an active role. In addition, we show how the thermal state of the resonator can be probed and even modified by an external, counter-propagating optical field, thus hinting towards novel approaches for all-optical control and sensing applications. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

The FD-FWM is a proven approach to implement coherent Microcomb generation. Comb repetition rates can be finely controlled in a robust way, while maintaining the coherence during the whole process, whereas full-coherent type-I and type-II combs can be accessible. We present our recent advances towards effective control of optical combs exploiting integrated chip-based resonators.

We experimentally demonstrate the generation of highly coherent Type-II micro-combs based on a microresonator nested in a fiber cavity loop, known as the filter-driven four wave mixing (FD-FWM) laser scheme. In this system, the frequency spacing of the comb can be adjusted to integer multiples of the free-spectral range (FSR) of the nested micro-resonator by properly tuning the fiber cavity length. Sub-comb lines with single FSR spacing around the primary comb lines can be generated. Such a spectral emission is known as a “Type-II comb.” Our system achieves a fully coherent output. This behavior is verified by numerical simulations. This study represents an important step forward in controlling and manipulating the dynamics of an FD-FWM laser.

In this contribution, we will review our recent activities in the development of double nested cavity lasers. Several stable operating regimes can be achieved over a wide range of conditions.

We demonstrate a robust control over the repetition rate of a micro-comb laser by using the Filter-Driven Four Wave Mixing scheme. Results show that the coherence can be kept during the whole process.

We numerically and experimentally demonstrate the generation of Type II micro-combs in a Filter-Driven four wave mixing laser, showing that the generated Type II micro-combs are fully coherent.

8 págs.; 6 figs.; Open Access funded by Creative Commons Atribution Licence 4.0, Ultrafast laser processing applications need fast approaches to assess the nonlinear propagation of the laser beam in order to predict the optimal range of processing parameters in a wide variety of cases. We develop here a method based on the simple monitoring of the nonlinear beam shaping against numerical prediction. The numerical code solves the nonlinear Schrodinger equation with nonlinear absorption under simplified conditions by employing a state-of-the art computationally efficient approach. By comparing with experimental results we can rapidly estimate the nonlinear refractive index and nonlinear absorption coefficients of the material. The validity of this approach has been tested in a variety of experiments where nonlinearities play a key role, like spatial soliton shaping or fs-laser waveguide writing. The approach provides excellent results for propagated power densities for which free carrier generation effects can be neglected. Above such a threshold, the peculiarities of the nonlinear propagation of elliptical beams enable acquiring an instantaneous picture of the deposition of energy inside the material realistic enough to estimate the effective nonlinear refractive index and nonlinear absorption coefficients that can be used for predicting the spatial distribution of energy deposition inside the material and controlling the beam in the writing process., This work has been partly funded by MINECO TEC2011-22422 project. J. de H. acknowledges funding from the JAE CSIC Program (pre-doctoral fellowship co-funded by the European Social Fund). A.P. acknowledges support from the People Program (Marie Curie Actions) Incoming International Fellowship (CHRONOS) under REA grant agreement nu [327627].

In this paper, we demonstrate a novel dual-pump approach to generate robust optical frequency comb with varying free spectral range (FSR) spacing in a CMOS-compatible high-Q micro-ring resonator (MRR). The frequency spacing of the comb can be tuned by an integer number FSR of the MRR freely in our dual-pump scheme. The dual pumps are self-oscillated in the laser cavity loop and their wavelengths can be tuned flexibly by programming the tunable filter embedded in the cavity. By tuning the pump wavelength, broadband OFC with the bandwidth of >180 nm and the frequency-spacing varying from 6 to 46-fold FSRs is realized at a low pump power. This approach could find potential and practical applications in many areas, such as optical metrology, optical communication and signal processing systems, for its excellent flexibility and robustness.

Passive fiber mode-locked lasers enable the excitation of multiple pulses per round trip representing a potential solutions for the increasing demand of practical optical sources with repetition rates of hundreds of GHz or higher. The control of such high repetition rate regimes is however a challenge. To this purpose, linear filters have been used in an "intracavity" configuration to force the repetition rate of the laser. This design is known as dissipative four wave mixing (DFWM) but it is usually unstable and hence marginally suitable for practical applications. We explore the use of nonlinear intracavity filters, such as integrated micro-ring resonators, capable of “driving” the FWM interaction in the laser. We term this approach as Filter-Driven FWM. With a proper choice of the filter properties in terms of free spectral range (FSR) and Q factor, we could observe stable regimes over a wide range of operating conditions, from high repetition rate oscillation at a 200GHz to the formation of two stable spectral comb replicas separated by the FSR of the main cavity (65MHz). High order filters, moreover, allow achieving nonlinear operation over large passbands. With an 11th order filter we achieve low-frequency mode-locking between the main cavity modes that oscillate within each resonance of the filter, producing burst pulsed operation. A stable mode-locked pulse train at 655GHz with an envelope of 42ps at 6.45MHz is achieved.

We demonstrate temporal measurements of sub-picosecond optical pulses via time-to-frequency conversion in a 45-cm-long CMOS compatible high-index glass spiral waveguide. The measurements are based on efficient four-wave mixing in the C-band, using around 1 W of peak pump power. We achieve a resolution of 400 fs over a time window of 100 ps, representing a time-bandwidth product >; 250.

We report on light-induced optical tuning of colloidal photonic crystals doped with gold nanoparticles (Au-nps). By resonantly exciting the Au-np surface plasmon absorption with picosecond pulses at 0.53 micron in a standard pump-probe setup, we observed permanent changes in the stop band resonance around 1.7 micron, with blue wavelength shifts as large as 30 nm and associated to a nanoparticle reshaping. Fine tuning was achieved by controlling either the pulse energy or the irradiation time.

We summarize here our recent results on high-repetition-rate laser mode-locking via microring resonators. The recent realization of multiple wavelength oscillators based on high Q-factor resonators has profoundly impacted optical frequency combs for metrology and precision measurements and other areas. The ability to mode-lock these devices is important for achieving high-precision optical clocks in a monolithic format, offering enormous benefits in performance, cost, size, and power consumption for optical waveform synthesis, high-capacity telecommunications, optical analog-to-digital conversion, and many other applications. Here, we demonstrated a mode-locked laser based on a monolithic high Q resonator. This device produces stable, self-starting transform-limited optical pulses at 200.3 GHz, with a sub-100 kHz linewidth and extremely narrow amplitude noise bandwidth of

We demonstrated a 1.81 μm mode-locked figure-eight laser using an integrated 11-th order microring resonator. Mode-locked train centered at 1.81 μm with repetition rate of 9.09 MHz is achieved.

Nonlinear optical processes are one of the most important tools in modern optics with a broad spectrum of applications in, for example, frequency conversion, spectroscopy, signal processing and quantum optics. For practical and ultimately widespread implementation, on-chip devices compatible with electronic integrated circuit technology offer great advantages in terms of low cost, small footprint, high performance and low energy consumption. While many on-chip key components have been realized, to date polarization has not been fully exploited as a degree of freedom for integrated nonlinear devices. In particular, frequency conversion based on orthogonally polarized beams has not yet been demonstrated on chip. Here we show frequency mixing between orthogonal polarization modes in a compact integrated microring resonator and demonstrate a bi-chromatically pumped optical parametric oscillator. Operating the device above and below threshold, we directly generate orthogonally polarized beams, as well as photon pairs, respectively, that can find applications, for example, in optical communication and quantum optics., On-chip nonlinear optics devices find a number of applications in modern optics from spectroscopy to communications. Here, the authors increase the degrees of freedom for frequency mixing by demonstrating the nonlinear interaction of perpendicularly-polarized modes in an integrated microring resonator.

Undular bores are among the most interesting phenomena in nature. A familiar case is the tidal bore: A stable, moving water wave front caused by a large rise in sea level into a narrow channel during a flood tide. In essence, the front is a traveling wave that is continuously breaking, like waves hitting a shoreline. Undular bores can occur under specific conditions that cause the moving front to leave behind a nonstationary oscillating wave train [1]. Numerous examples illustrating this phenomenon can be found in nature (Fig. 1), ranging from the formation of large-scale atmospheric gravity waves (seen in the so-called “Morning Glory” phenomenon in Australia, for example) to impressive tidal bores appearing in several river estuaries all over the world (such as the Peticodiac River tidal bore in Canada). Now, reporting in Physical Review X, Julien Fatome at the University of Bourgogne, France, and colleagues demonstrate how faithfully these hydrodynamic phenomena can be recreated and studied in optical analog experiments [2]. In these experiments, they see waves reminiscent of undular bores, generated as light waves propagate in an optical fiber.

Spatial solitary waves induced by quadratic nonlinearities have been the subject of many theoretical and experimental investigations in the last decade, with extensive studies being devoted to soliton formation in 1D nonlinear photonic crystals (NPC) such as PPLN (periodically poled LiNbO3). Here we present results on a new class of (1 + 1)D spatial solitary waves, the first examples of quadratic self-confinement in a 2D NPC.

We demonstrate a range of novel functions based on a high index doped silica glass CMOS compatible platform. This platform has promise for telecommunications and onchip WDM optical interconnects for computing.

We demonstrate novel microcavity lasers in an integrated, CMOS compatible platform. This platform has promise for telecommunications and on-chip WDM optical interconnects.

Ultrashort pulsed lasers, operating through the phenomenon of mode-locking, have had a significant role in many facets of our society for 50 years, for example, in the way we exchange information, measure and diagnose diseases, process materials, and in many other applications. Recently, high-quality resonators have been exploited to demonstrate optical combs. The ability to phase-lock their modes would allow mode-locked lasers to benefit from their high optical spectral quality, helping to realize novel sources such as precision optical clocks for applications in metrology, telecommunication, microchip-computing, and many other areas. Here we demonstrate the first mode-locked laser based on a microcavity resonator. It operates via a new mode-locking method, which we term filter-driven four-wave mixing, and is based on a CMOS-compatible high quality factor microring resonator. It achieves stable self-starting oscillation with negligible amplitude noise at ultrahigh repetition rates, and spectral linewidths well below 130 kHz., Stable, ultrahigh repetition rate optical clocks are critical for applications in high-speed communications, metrology and microchip computing. Peccianti et al. present a mode-locked laser based on an integrated microcavity, with repetition rate exceeding 200 GHz and narrow linewidth pulses.

We report a mode locked laser based on an integrated high-Q microring resonator with a highly monochromatic radiofrequency modulation thanks to the stable operation of two slightly shifted spectral optical comb replicas.

We report a mode locked laser based on an integrated high-Q microring resonator with a highly monochromatic radiofrequency modulation thanks to the stable operation of two slightly shifted spectral optical comb replicas.

We demonstrate a stable passively mode locked soliton laser that extends the Dissipative-FWM concept, in a highly nonlinear, CMOS compatible integrated micro-ring resonator. Operation at 200GHz, free of supermode instability, is demonstrated.

All-optical signal processing has been demonstrated extensively in Si including demultiplexing at 160Gb/s via four-wave mixing (FWM) [1] and optical regeneration [2], as well as in chalcogenide glass (ChG) waveguides[3]. The efficiency of all-optical devices can be improved by increasing the nonlinear parameter, γ = ω n 2 / c A eff (A eff is the waveguide effective area, n 2 is the Kerr nonlinearity) as well as by using resonant structures to enhance the local field intensity. Semiconductors and ChG offer excellent optical confinement and a high n 2 that has produced γ's of 200,000 W−1 km−1 for Si nanowires [2], and 93,400 W−1 km−1 in ChG nanotapers [4]. Yet silicon suffers from a poor intrinsic nonlinear figure of merit (FOM = n 2 / (β λ), where β is the two-photon absorption coefficient) due to two-photon absorption (TPA) and the resulting free carriers [5]. Here, we report a wide range of functions in a CMOS compatible high index doped silica glass platform, including an integrated multiple wavelength source [6,7], an ultra-high repetition rate modelocked laser [8], and an all-optical integrator[9]. We achieve CW oscillation in a Q=1.2 million micro-ring resonator with a slope efficiency of 7.4% (single oscillating mode, single port), a threshold power of 54mW, and frequency spacings from 200GHz to > 6THz. We also achieve modelocking with repetition rates as high as 800GHz [9]. We also report novel functions in ultra-long (45cm) spiral waveguides, including a time-lens optical oscilloscope and parametric amplifier with > 15dB of gain [10]. The success of these devices is due to very low linear loss, negligible nonlinear loss (up to 25GW/cm2), and a high γ ≅ 233W−1km−1. The low loss, design flexibility, and CMOS compatibility of this platform will enable devices for telecommunications, computing, sensing, metrology and other areas.

We demonstrate a wide range of novel functions in integrated, CMOS compatible, devices. This platform has promise for telecommunications and on-chip WDM optical interconnects for computing.

We present a dissipative four wave mixing tunable laser based on a integrated CMOS-compatible high-Q nonlinear ring resonator, emitting subpicosecond pulses at 200GHz-repetition rate. Quasi-sinusoidal 800GHz emission regime is also demonstrated.

We present an investigation on the nonlinear dynamics of intense pulses in an AlGaAs Bragg waveguide and we report the experimental observation of an intensity dependent blue-shift of the Bragg notch spectral line.

We present a dissipative four wave mixing tunable laser based on a integrated CMOS-compatible high-Q nonlinear ring resonator, emitting subpicosecond pulses at 200GHz-repetition rate. Quasi-sinusoidal 800GHz emission regime is also demonstrated.

We present a subpicosecond, ultrahigh repetition rate, passively mode-locked laser based on four-wave mixing in an integrated CMOS-compatible high-Q nonlinear ring resonator.

We present a subpicosecond, 200GHz-repetition rate, passively mode-locked laser based on the dissipative four-wave mixing scheme exploiting a integrated CMOS-compatible high-Q nonlinear ring resonator.

We present a subpicosecond, 200GHz-repetition rate, passively mode-locked laser based on high-harmonic four-wave mixing in an integrated CMOS-compatible high-Q nonlinear ring resonator.

We present a dissipative four wave mixing tunable laser based on a integrated CMOS-compatible high-Q nonlinear ring resonator, emitting subpicosecond pulses at 200GHz-repetition rate. Quasi-sinusoidal 800GHz emission regime is also demonstrated.

We report on the observation of Type I third-harmonic generation induced by a train of femtosecond laser pulses in nematic liquid crystals. We find that as the average power of the train is increased, the frequency conversion process is enhanced as a consequence of the tight confinement of the pulses into a nonlocal spatial soliton. (C) 2010 Optical Society of America

We report an integrated all-optical radio frequency spectrum analyzer based on a ~4 cm long doped silica glass waveguide, with a bandwidth greater than 2.5 THz. We use this device to characterize the intensity power spectrum of ultrahigh repetition rate mode-locked lasers at repetition rates up to 400 GHz, and observe dynamic noise related behavior not observable with other techniques.

Future photonic materials and optical integration strategies will likely be compatible with current CMOS fabrication technologies and platforms. We demonstrated that it is possible to obtain modelocked soliton pulse emission in a fiber loop laser by combining the nonlinear element with the high-finesse filter, exploiting a novel interaction mechanism that we termed filter-driven four wave mixing (FD-FWM).

We demonstrate a novel mode locked ultrafast laser, based on an integrated high-Q microring resonator. Our scheme exhibits stable operation of two slightly shifted spectral optical comb replicas. It generates a highly monochromatic radiofrequency modulation of 65.8MHz with a linewidth < 10kHz, on a 200GHz output pulse train.

We report an on-chip all-optical CMOS-compatible radio frequency spectrum analyzer with a bandwidth exceeding 2.5 THz, and use it to measure the intensity power spectra of mode-locked lasers with repetition rates up to 400 GHz.

We demonstrated a new regime of operation for ultrafast mode-locked lasers that we termed "burst-mode" modelocking. By exploiting an integrated 11th order micro-ring resonator, our scheme achieves stable operation resulting in a mode-locked train of pulses at 650 GHz with a burst mode envelope of 40 ps at 7.12 MHz.