arXiv subjects

Artem E. Shitikov

Publications and source records attributed to Artem E. Shitikov.

17 recordsLinked to original sources

arXiv2026

Platicon purification in self-injection locking regime via gain switching

Integrated photonic devices leveraging optical frequency microcombs have emerged as essential instruments for modern photonic systems, prized for their chip-scale footprint, high energy efficiency, and inherent stability. This work introduces a novel approach to microwave photonic oscillator based on generation of a Kerr platicon microcomb by a gain-switched self-injection-locked distributed feedback (DFB) laser diode. The system leverages direct modulation of the current of the laser diode, generating optical sidebands around the pump line. The beatnote between the Kerr comb lines and sidebands of the modulated pump at a high-speed photodetector allows to obtain tunable, low-noise microwave signals at frequencies close to the platicon repetition rate, which is many times higher than used for gain switching. We experimentally demonstrate continuous microwave signal frequency tuning from 100 MHz to 3.6 GHz by sweeping the modulation frequency, thereby shifting the generated sidebands relative to a platicon beatnote. We match third harmonics of the modulation frequency of the gain-switch signal with the free spectral range of the microresonator simultaneously generating the platicon microcomb. That leads to significant spectral purification of the platicon beatnote decreasing its phase noise by more than 30 dB. The novel architecture proposed offers a robust and versatile method for microwave synthesis, presenting significant potential for the advancement of integrated microwave photonic systems and their applications in communications, sensing, and metrology.

physics.optics↗

arXiv2026

Low-Threshold Degenerate Optical Parametric Oscillations in Bichromatically-Pumped Normal-Dispersion Photonic-Crystal Microresonator

The process of excitation of degenerate optical parametric oscillations via bichromatic pump is studied numerically in normal-dispersion photonic-crystal microresonator. It is demonstrated that the photonic-crystal structure with two split modes placed symmetrically at the particular interval from the pumped modes provides significant reduction in pump power threshold for the considered process. The parameter range for this phenomenon is determined. Introduction of mode splitting at the signal mode located in the center between pumped modes leads to an increase in the generation threshold.

physics.optics↗

arXiv2025

Stokes microcombs in silicon nitride microresonators

Silicon nitride microresonators have become an ubiquitous platform for cutting-edge photonics applications. Improvement in silicon nitride fabrication techniques, providing ultra-high quality-factor values up to $10^7$, has opened up new possibilities for nonlinear effects realizations in such structures. Here we report for the first time to our knowledge on the observation of the Stokes microcombs in silicon nitride on-chip microresonators exhibiting normal group velocity dispersion. Moreover, using different pump schemes, namely, a tunable laser with an isolator and a stabilized diode laser, we demonstrate on-chip stimulated Raman frequency combs including dark-pulse Raman states. We reveal a complex interplay between Kerr and Raman nonlinearities and elaborate effective method of controllable switching between predominantly Kerr-comb and predominantly Raman-comb operation. We prove the Raman-induced platicon formation by numerical model which shows perfect agreement with experimental results. These findings are of special importance for silicon nitride photonics and provide a basis for novel photonic devices.

physics.optics↗

arXiv2025

Optimization of the degenerate optical parametric oscillations threshold in bichromatically pumped microresonator

Integrated microring resonators have a broad range of applications in diverse fields with the potential to design compact, robust, energy-efficient devices crucial for quantum applications. Degenerate optical parametric oscillations (DOPOs) realized in dual-pumped microring resonator with third-order optical nonlinearity are of special interest. They demonstrate both bistability of the phase of the excited signal mode and generation of nonclassical light, which can be used for coherent photonic computing. Using coupled mode equations, we perform a comprehensive numerical analysis of DOPO conditions with normal group velocity dispersion and with bichromatic pumping. Through analytical and numerical approaches, we identify optimal setup parameter values that minimize the threshold power, highlighting the importance of considering the full spectrum of mode interactions. Additionally, we show that dispersion engineering, achievable in photonic molecules or photonic crystal microresonators, may provide a targeted frequency shift of specific microresonator modes resulting in pump power threshold reduction.

physics.optics↗

arXiv2025

Universal Kerr-thermal dynamics of self-injection-locked microresonator dark pulses

Microcombs, formed in optical microresonators driven by continuous-wave lasers, are miniaturized optical frequency combs. Leveraging integrated photonics and laser self-injection locking (SIL), compact microcombs can be constructed via hybrid integration of a semiconductor laser with a chip-based microresonator. While the current linear SIL theory has successfully addressed the linear coupling between the laser cavity and the external microresonator, it fails to describe the complicated nonlinear processes, especially for dark-pulse microcomb formation. Here, we investigate -- theoretically, numerically and experimentally -- the Kerr-thermal dynamics of a semiconductor laser self-injection-locked to an integrated silicon nitride microresonator. We unveil intriguing yet universal dark-pulse formation and switching behaviour with discrete steps, and establish a theoretical model scrutinizing the synergy of laser-microresonator mutual coupling, Kerr nonlinearity and photo-thermal effect. Numerical simulation confirms the experimental result and identifies the origins. Exploiting this unique phenomenon, we showcase an application on low-noise photonic microwave generation with phase noise purified by 23.5 dB. Our study not only adds critical insight of pulse formation in laser-microresonator hybrid systems, but also enables all-passive, photonic-chip-based microwave oscillators with high spectral purity.

physics.optics↗

arXiv2022

Recent Advances in Laser Self-Injection Locking to High-$Q$ Microresonators

The stabilization and manipulation of laser frequency by means of an external cavity are nearly ubiquitously used in fundamental research and laser applications. While most of the laser light transmits through the cavity, in the presence of some back-scattered light from the cavity to the laser, the self-injection locking effect can take place, which locks the laser emission frequency to the cavity mode of similar frequency. The self-injection locking leads to dramatic reduction of laser linewidth and noise. Using this approach, a common semiconductor laser locked to an ultrahigh-$Q$ microresonator can obtain sub-hertz linewidth, on par with state-of-the-art fiber lasers. Therefore it paves the way to manufacture high-performance semiconductor lasers with reduced footprint and cost. Moreover, with high laser power, the optical nonlinearity of the microresonator drastically changes the laser dynamics, offering routes for simultaneous pulse and frequency comb generation in the same microresonator. Particularly, integrated photonics technology, enabling components fabricated via semiconductor CMOS process, has brought increasing and extending interest to laser manufacturing using this method. In this article, we present a comprehensive tutorial on analytical and numerical methods of laser self-injection locking, as well a review of most recent theoretical and experimental achievements.

physics.optics↗

arXiv2022

Optimization of laser stabilization via self-injection locking to a whispering-gallery-mode microresonator: experimental study

Self-injection locking of a diode laser to a high-quality-factor microresonator is widely used for frequency stabilization and linewidth narrowing. We constructed several microresonator-based laser sources with measured instantaneous linewidths of 1 Hz and used them for investigation and implementation of the self-injection locking effect. We studied analytically and experimentally the dependence of the stabilization coefficient on tunable parameters such as locking phase and coupling rate. It was shown that precise control of the locking phase allows fine tuning of the generated frequency from the stabilized laser diode. We also showed that it is possible for such laser sources to realize fast continuous and linear frequency modulation by injection current tuning inside the self-injection locking regime. We conceptually demonstrate coherent frequency-modulated continuous wave LIDAR over a distance of 10 km using such a microresonator-stabilized laser diode in the frequency-chirping regime and measure velocities as low as sub-micrometer per second in the unmodulated case. These results could be of interest for cutting-edge technology applications such as space debris monitoring and long-range object classification, high resolution spectroscopy and others.

physics.optics↗

arXiv2022

Platicon Stability in Hot Cavities

The stability of platicons in hot cavities with normal group velocity at the interplay of Kerr and thermal nonlinearities was addressed numerically. The stability analysis was performed for different ranges of pump amplitude, thermal nonlinearity coefficient and thermal relaxation time. It was revealed that for the positive thermal effect, the high-energy wide platicons are stable, while the negative thermal coefficient provides the stability of narrow platicons.

physics.optics↗

arXiv2022

Ultra high-Q WGM microspheres from ZBLAN for the mid-IR band

The advantages of high-quality-factor whispering gallery mode microresonators can be applied to develop novel photonic devices for the mid-IR range. ZBLAN (glass based on heavy metal fluorides) is one of the most promising materials to be used for this purpose due to low optical losses in the mid-IR. We developed original fabrication method based on melting of commercially available ZBLAN-based optical fiber to produce high-Q ZBLAN microspheres with the diameters of 250 to 350 $μ$m. We effectively excited whispering gallery modes in these microspheres and demonstrated high quality factor both at 1.55 $μ$m and 2.64 $μ$m. Intrinsic quality factor at telecom wavelength was shown $(5.4\pm0.4)\cdot10^8$ which is defined by the material losses in ZBLAN. In the mid-IR at 2.64 $μ$m we demonstrated record quality factor in ZBLAN exceeding $10^8$ which is comparable to the highest values of the Q-factor among all materials in the mid-IR.

physics.optics↗

arXiv2022

Dual-laser self-injection locking to an integrated microresonator

Diode laser self-injection locking (SIL) to a whispering gallery mode of a high quality factor resonator is a widely used method for laser linewidth narrowing and high-frequency noise suppression. SIL has already been used for the demonstration of ultra-low-noise photonic microwave oscillators and soliton microcomb generation and has a wide range of possible applications. Up to date, SIL was demonstrated only with a single laser. However, multi-frequency and narrow-linewidth laser sources are in high demand for modern telecommunication systems, quantum technologies, and microwave photonics. Here we experimentally demonstrate the dual-laser SIL of two multifrequency laser diodes to different modes of an integrated Si$_3$N$_4$ microresonator. Simultaneous spectrum collapse of both lasers, as well as linewidth narrowing and high-frequency noise suppression , as well as strong nonlinear interaction of the two fields with each other, are observed. Locking both lasers to the same mode results in a simultaneous frequency and phase stabilization and coherent addition of their outputs. Additionally, we provide a comprehensive dual-SIL theory and investigate the influence of lasers on each other caused by nonlinear effects in the microresonator.

physics.optics↗

arXiv2021

Generation of Vector Platicons and Hybrid Soliton-Platicon Complexes in Optical Microresonators via Modulated Pump

We demonstrate numerically the possibility of generation of vector platicons having orthogonally polarized components by the modulated pump at normal GVD. Dynamics of this process can be controlled by pump polarization and depends on both the spectral interval between pumped modes and the difference of their FSRs. We also show the possibility of the excitation of the hybrid soliton-platicon complexes if pumped modes have alternating signs of the GVD coefficient.

physics.optics↗

arXiv2021

Self-injection locking of the gain-switched laser diode

We experimentally observed self-injection locking regime of the gain-switched laser to high-Q optical microresonator. We revealed that comb generated by the gain-switched laser experiences a dramatic reduce of comb teeth linewidths in this regime. We demonstrated the Lorentzian linewidth of the comb teeth of sub-kHz scale as narrow as for non-switched self-injection locked laser. Such setup allows generation of high-contrast electrically-tunable optical frequency combs with tunable comb line spacing in a wide range from 10 kHz up to 10 GHz. The characteristics of the generated combs were studied for various modulation parameters - modulation frequency and amplitude, and for parameters, defining the efficiency of the self-injection locking - locking phase, coupling efficiency, pump frequency detuning.

physics.optics↗

arXiv2020

Microresonator and Laser Parameters Definition via Self-Injection Locking

Self-injection locking to a high-quality-factor microresonator is a key component of various up-to-date photonic applications, including compact narrow-linewidth lasers and microcomb sources. For optimal construction of such devices it is necessary to know the parameters of the locking mode, which is a challenging task. We developed and verified experimentally an original technique based on the fundamentals of the self-injection locking effect, which allows determining the key parameters of the mode of the microresonator (quality factor, vertical index) as well as laser diode parameters. We demonstrated that this method can be used in the spectral ranges where conventional methods are not applicable, for example, in the mid-IR. We stabilized a 2.64 $μ$m laser diode by a high-Q whispering gallery mode microresonator made of crystalline silicon. Using the elaborated technique, the quality factor of the microresonator was determined to be $5\cdot10^8$.

physics.optics↗

arXiv2020

Two-color flat-top solitonic pulses in $χ^{(2)}$ optical microresonators via second harmonic generation

We studied numerically the generation of the coherent frequency combs at second harmonic generation in $χ^{(2)}$ microresonators via conventional frequency scan method. It was demonstrated for the first time that under particular conditions it is possible to generate two-color flat-top solitonic pulses, platicons, using pump amplitude modulation or controllable mode interaction approach, if the signs of the group velocity coefficients at pump frequency and its second harmonic are opposite but absolute values of these coefficients are rather close. It was revealed that platicons may be observed on both sides of the linear microresonator resonance (at positive, as well as negative pump frequency detunings). For the efficient platicon excitation, one needs simultaneous accurate matching of both microresonator free spectral ranges and resonant eigenfrequencies. Platicon generation processes were simulated numerically, excitation conditions and platicon generation domains were found for different generation methods, and the properties of generated platicons were studied for the different combinations of the medium parameters.

physics.optics↗

arXiv2019

Generation and dynamics of solitonic pulses due to pump amplitude modulation at normal group velocity dispersion

We studied generation and dynamics of solitonic pulses, platicons, at normal group velocity dispersion due to the pump amplitude modulation. We proposed, that if the required frequency of amplitude modulation is too large for available modulators, it is possible to use subharmonic phase modulation for platicon generation. It was also demonstrated that it is possible to control the repetition rate of platicons by tuning modulation frequency. Tuning range for platicons was found to be much wider than for bright solitons. We also studied the influence of the high-order dispersion on platicon properties. It was shown that both third-order dispersion and pump modulation govern platicon dynamics making it quite different from dynamics of dissipative Kerr solitons. Third-order dispersion was also shown to affect significantly the optimal conditions for the platicon generation and repetition rate tuning range.

physics.optics↗

arXiv2018

Electrically pumped photonic integrated soliton microcomb

Optical frequency combs have revolutionized frequency metrology and timekeeping, and can be used in a wide range of optical technologies. Advances are under way that allow dramatic miniaturization of optical frequency combs using Kerr nonlinear optical microresonators, where broadband and coherent optical frequency combs can be generated from a continuous wave laser. Such `microcombs', provide a broad bandwidth with low power consumption, unprecedented form factor, wafer scale fabrication compatibility. For future high volume applications, integration and electrical pumping of soliton microcombs is essential. To date, however, microcombs still rely on optical pumping by bulk external laser modules that provide the required coherence, frequency agility and power levels for soliton formation. Electrically-driven, chip-integrated microcombs are inhibited by the high threshold power for soliton formation, typically exceeding the power of integrated silicon based lasers, and the required frequency agility for soliton initiation. Recent advances in high-Q Si3N4 microresonators suggest that electrically driven soliton microcombs are possible. Here we demonstrate an electrically-driven, chip-integrated soliton microcomb by coupling an indium phosphide (III-V) multiple-longitudinal-mode laser diode chip to a high-Q Si3N4 photonic integrated microresonator. We observe that self-injection locking of the laser diode to the microresonator, which is accompanied by a x1000 fold narrowing of the laser linewidth, can simultaneously initiate the formation of dissipative Kerr solitons. By tuning the current, we observe a transition from modulation instability, breather solitons to single soliton states. The system requires less than 1 Watt of electrical power, operates at electronically-detectable sub-100 GHz mode spacing and can fit in a volume of ca. 1cm3.

physics.optics↗

arXiv2017

Dynamics of platicons due to third-order dispersion

Dynamics of platicons caused by the third-order dispersion is studied. It is shown that under the influence of the third-order dispersion platicons obtain angular velocity depending both on dispersion and on detuning value. A method of tuning of platicon associated optical frequency comb repetition rate is proposed.

physics.optics↗