arXiv subjects

Dmitry Kazakov

Publications and source records attributed to Dmitry Kazakov.

17 recordsLinked to original sources

arXiv2026

A swept-source dual-comb spectrometer on a chip

Dual-comb spectroscopy (DCS) enables high-speed, high-resolution spectroscopy by down-converting optical spectra to the radio-frequency (RF) domain through the interference of two mutually detuned frequency combs. Accurately resolving narrow molecular absorption features requires closely spaced comb lines generated by large laser cavities with long round-trip times, thereby hindering the miniaturization of high-resolution spectrometers. Here, we circumvent this limitation by demonstrating a swept-source dual-comb spectrometer using two unidirectional racetrack semiconductor lasers integrated on the same chip. The traveling-wave frequency combs are generated by strong RF injection at the laser cavity round-trip frequency of 14.3~GHz and are continuously tuned in frequency by varying the laser drive currents. This enables continuous spectral sampling over a 32~cm$^{-1}$ range centered near 8~\textmu m, with an effective sampling interval of approximately 80~MHz. The outputs of both combs are coupled into the same monolithically integrated light coupler, providing automatic collinear alignment before the combined beam interrogates the sample. We benchmark the spectrometer against an external-cavity tunable laser and validate its performance using HITRAN simulations for 1.25\% nitrous oxide. Finally, the unidirectional comb architecture suppresses the detrimental effects of optical feedback, yielding comparable residuals even under deliberately introduced strong feedback. More broadly, the benefits of miniaturization extend beyond reduced footprint: chip-scale integration enables new forms of electrical and optical control that can fundamentally change how dual-comb spectrometers are operated.

physics.optics↗

arXiv2025

High-power quantum walk frequency combs

High-power, broadband frequency combs generated by semiconductor lasers have profound implications for on-chip spectroscopy. Here, we present a dry-etched racetrack quantum cascade laser that uses resonant radio-frequency injection to produce a unidirectional quantum walk frequency comb at mid-infrared wavelengths. Efficient light outcoupling from the racetrack resonator provides more than 100 mW of continuous-wave output power at room temperature, with beam quality on par with that of Fabry--Perot lasers. Experimental waveform reconstruction confirms that the combs are frequency-modulated, rather than amplitude-modulated (as in active mode-locking). We show excellent agreement between the experimental waveforms and numerical simulations, which are based on a reduced Maxwell--Bloch model of the laser and include fast gain dynamics, finite group velocity dispersion, and large Kerr nonlinearity. Furthermore, our optimized device architecture -- featuring thick Si3N4 passivation and reduced parasitic capacitance -- enables modulation bandwidths exceeding 10 GHz. Combined with high output powers and the potential for monolithic integration of multiple ring lasers and waveguide couplers, these advances pave the way to fully integrated dual-comb spectrometers.

physics.optics↗

arXiv2024

Temporal solitons in active optical resonators

Solitons, as coherent structures that maintain their shape while traveling at constant velocity, are ubiquitous across various branches of physics, from fluid dynamics to quantum fields. However, it is within the realm of optics where solitons have not only served as a primary testbed for understanding solitary wave phenomena but have also transitioned into applications ranging from telecommunications to metrology. In the optical domain, temporal solitons are localized light pulses, self-reinforcing via a delicate balance between nonlinearity and dispersion. Among the many systems hosting temporal solitons, active optical resonators stand out due to their inherent gain medium, enabling to actively sustain solitons. Unlike conventional modelocked lasers, active resonators offer a richer landscape for soliton dynamics through hybrid driving schemes, such as coupling to passive cavities or under external optical injection, affording them unparalleled control and versatility. We discuss key advantages of these systems, with a particular focus on quantum cascade lasers as a promising soliton technology within the class of active resonators. By exploring diverse architectures from traditional Fabry-Perot cavities to racetrack devices operated under external injection, we present the current state-of-the-art and future directions for soliton-based sources in the realm of semiconductor lasers and hybrid integrated photonic systems.

physics.optics↗

arXiv2024

Lasing on hybridized soliton frequency combs

Coupling is an essential mechanism that drives complexity in natural systems, transforming single, non-interacting elements into intricate networks with rich physical properties. Here, we demonstrate a chip-scale coupled laser system that exhibits complex optical states impossible to achieve in an uncoupled system. We show that a pair of coupled semiconductor ring lasers spontaneously forms a frequency comb consisting of the hybridized modes of its coupled cavity, exhibiting a large number of phase-locked tones that anticross with one another. Experimental coherent waveform reconstruction reveals that the hybridized frequency comb manifests itself as pairs of bright and dark picosecond-long solitons circulating simultaneously. The dark and bright solitons exit the coupled cavity at the same time, leading to breathing bright solitons temporally overlapped with their dark soliton counterparts - a state inaccessible for a single, free-running laser. Our results demonstrate that the rules that govern allowable states of light can be broken by simply coupling elements together, paving the way for the design of more complex networks of coupled on-chip lasers.

physics.optics↗

arXiv2024

Driven bright solitons on a mid-infrared laser chip

Despite the ongoing progress in integrated optical frequency comb technology, compact sources of short bright pulses in the mid-infrared wavelength range from 3 {\mu}m to 12 {\mu}m so far remained beyond reach. The state-of-the-art ultrafast pulse emitters in the mid-infrared are complex, bulky, and inefficient systems based on the downconversion of near-infrared or visible pulsed laser sources. Here we show a purely DC-driven semiconductor laser chip that generates one picosecond solitons at the center wavelength of 8.3 {\mu}m at GHz repetition rates. The soliton generation scheme is akin to that of passive nonlinear Kerr resonators. It relies on a fast bistability in active nonlinear laser resonators, unlike traditional passive mode-locking which relies on saturable absorbers or active mode-locking by gain modulation in semiconductor lasers. Monolithic integration of all components - drive laser, active ring resonator, coupler, and pump filter - enables turnkey generation of bright solitons that remain robust for hours of continuous operation without active stabilization. Such devices can be readily produced at industrial laser foundries using standard fabrication protocols. Our work unifies the physics of active and passive microresonator frequency combs, while simultaneously establishing a technology for nonlinear integrated photonics in the mid-infrared.

physics.optics↗

arXiv2023

Nozaki-Bekki optical solitons

Recent years witnessed rapid progress of chip-scale integrated optical frequency comb sources. Among them, two classes are particularly significant -- semiconductor Fabry-Per\'{o}t lasers and passive ring Kerr microresonators. Here, we merge the two technologies in a ring semiconductor laser and demonstrate a new paradigm for free-running soliton formation, called Nozaki-Bekki soliton. These dissipative waveforms emerge in a family of traveling localized dark pulses, known within the famed complex Ginzburg-Landau equation. We show that Nozaki-Bekki solitons are structurally-stable in a ring laser and form spontaneously with tuning of the laser bias -- eliminating the need for an external optical pump. By combining conclusive experimental findings and a complementary elaborate theoretical model, we reveal the salient characteristics of these solitons and provide a guideline for their generation. Beyond the fundamental soliton circulating inside the ring laser, we demonstrate multisoliton states as well, verifying their localized nature and offering an insight into formation of soliton crystals. Our results consolidate a monolithic electrically-driven platform for direct soliton generation and open a door for a new research field at the junction of laser multimode dynamics and Kerr parametric processes.

physics.optics↗

arXiv2022

Point singularity array with metasurfaces

Phase singularities are loci of darkness surrounded by monochromatic light in a scalar field, with applications in optical trapping, super-resolution imaging, and structured light-matter interactions. Although 1D singular structures, such as optical vortices, are the most common due to their robust topological properties, uncommon 0D (point) and 2D (sheet) singular structures can be generated by wavefront-shaping devices such as metasurfaces. Here, using the design flexibility of metasurfaces, we deterministically position ten identical point singularities in a cylindrically symmetric field generated by a single illumination source. The phasefront is inverse-designed using phase gradient maximization with an automatically-differentiable propagator. This process produces tight longitudinal intensity confinement. The singularity array is experimentally realized with a 1 mm diameter TiO2 metasurface. One possible application is blue-detuned neutral atom trap arrays, for which this light field would enforce 3D confinement and a potential depth around 0.22 mK per watt of incident trapping laser power. Metasurface-enabled point singularity engineering may significantly simplify and miniaturize the optical architecture required to produce super-resolution microscopes and dark traps.

physics.optics↗

arXiv2022

Semiconductor ring laser frequency combs with active directional couplers

Rapid development of Fabry-Perot quantum cascade laser frequency combs has converted them from laboratory devices to key components of next-generation fast molecular spectrometers. Recently, free-running ring quantum cascade lasers allowed generation of new frequency comb states induced by phase turbulence. In absence of efficient light outcoupling, ring quantum cascade lasers are not suited for applications as they are limited in their power output to microwatt levels. Here we demonstrate electrically pumped ring quantum cascade lasers with integrated active directional couplers. These devices generate self-starting frequency combs and have output power above ten milliwatts at room temperature. We study the transmission of the ring-waveguide resonator system below the lasing threshold, which reveals the ability to individually control the mode indices in the coupled resonators, their quality factors, and the coupling coefficient. When the ring resonator is pumped above the lasing threshold, the intracavity unidirectional single-mode field parametrically amplifies an externally injected signal tuned into one of the ring resonances, generating an idler sideband via four-wave mixing. The ability to inject external optical signals into integrated laser cavities brings into reach coherent control of frequency comb states in ring semiconductor lasers. Furthermore, tunable coupled active resonators pumped below the lasing threshold enable a versatile platform for the studies of resonant electromagnetic effects, ranging from strong coupling to parity-time symmetry breaking.

physics.optics↗

arXiv2021

Gigahertz free-space electro-optic modulators based on Mie resonances

Electro-optic modulators from non-linear $\chi^{(2)}$ materials are essential for sensing, metrology and telecommunications because they link the optical domain with the microwave domain. At present, most geometries are suited for fiber applications. In contrast, architectures that modulate directly free-space light at gigahertz (GHz) speeds have remained very challenging, despite their dire need for active free-space optics, in diffractive computing or for optoelectronic feedback to free-space emitters. They are typically bulky or suffer from much reduced interaction lengths. Here, we employ an ultrathin array of sub-wavelength Mie resonators that support quasi bound states in the continuum (BIC) as a key mechanism to demonstrate electro-optic modulation of free-space light with high efficiency at GHz speeds. Our geometry relies on hybrid silicon-organic nanostructures that feature low loss ($Q = $ 550 at $\lambda_{res} = 1594$ nm) while being integrated with GHz-compatible coplanar waveguides. We maximize the electro-optic effect by using high-performance electro-optic molecules (whose electro-optic tensor we engineer in-device to exploit $r_{33} = 100$ pm/V) and by nanoscale optimization of the optical modes. We demonstrate both DC tuning and high speed modulation up to 5~GHz ($f_{EO,-3 dB} =3$ GHz) and shift the resonant frequency of the quasi-BIC by $\Delta\lambda_{res}=$11 nm, surpassing its linewidth. We contrast the properties of quasi-BIC modulators by studying also guided mode resonances that we tune by $\Delta\lambda_{res}=$20 nm. Our approach showcases the potential for ultrathin GHz-speed free-space electro-optic modulators.

physics.optics↗

arXiv2021

Spectrally resolved linewidth enhancement factor of a semiconductor frequency comb

The linewidth enhancement factor (LEF) has recently moved into the spotlight of research on frequency comb generation in semiconductor lasers. Here we present a novel modulation experiment, which enables the direct measurement of the spectrally resolved LEF in a laser frequency comb. By utilizing a phase-sensitive technique, we are able to extract the LEF for each comb mode. We first investigate and verify this universally applicable technique using Maxwell-Bloch simulations and then present the experimental demonstration on a quantum cascade laser frequency comb.

physics.optics↗

arXiv2019

Semiconductor ring laser frequency combs induced by phase turbulence

Semiconductor ring lasers are miniaturized devices that operate on clockwise and counterclockwise modes. These modes are not coupled in the absence of intracavity reflectors, which prevents the formation of a standing wave in the cavity and, consequently, of a population inversion grating. This should inhibit the onset of multimode emission driven by spatial hole burning. Here we show that, despite this notion, ring quantum cascade lasers inherently operate in phase-locked multimode states, that switch on and off as the pumping level is progressively increased. By rewriting the master equation of lasers with fast gain media in the form of the complex Ginzburg-Landau equation, we show that ring frequency combs stem from a phase instability---a phenomenon also known in superconductors and Bose-Einstein condensates. The instability is due to coupling of the amplitude and phase modulation of the optical field in a semiconductor laser, which plays the role of a Kerr nonlinearity, highlighting a connection between laser and microresonator frequency combs.

physics.optics↗

arXiv2018

Beyond the Standard Model' 17

We discuss the status of the SM - The principles - The Lagrangian - The problems - Open questions - The ways beyond. Then we consider possible physics beyond the SM - New symmetries (Gauge, SUSY, etc) - New particles (gauge, axion, superpartners) - New dimensions (extra, large, compact, etc) - New Paradigm (strings, branes, gravity). In conclusion, we formulate the first priority tasks for the future HEP program.

hep-ph↗

arXiv2018

Kinematically Dependent Renormalization

We suggest a renewed view on non-renormalizable interactions treated perturbatively within a kinematically dependent renormalization procedure. It is based on the usual BPHZ R-operation which is equally applicable to any local QFT independently whether it is renormalizable or not. The key point is that the renormalization constant becomes the function of kinematical variables acting as an operator on the amplitude. The procedure is demonstrated by the example of D=8 supersymmetric gauge theory considered within the spinor helicity formalism.

hep-th↗

arXiv2017

Self-starting harmonic frequency comb generation in a quantum cascade laser

Optical frequency combs establish a rigid phase-coherent link between microwave and optical domains and are emerging as high-precision tools in an increasing number of applications. Frequency combs with large intermodal spacing are employed in the field of microwave photonics for radiofrequency arbitrary waveform synthesis and for generation of THz tones of high spectral purity in the future wireless communication networks. We demonstrate for the first time self-starting harmonic frequency comb generation with a THz repetition rate in a quantum cascade laser. The large intermodal spacing caused by the suppression of tens of adjacent cavity modes originates from a parametric contribution to the gain due to temporal modulations of the population inversion in the laser. The mode spacing of the harmonic comb is shown to be uniform to within $5\times 10^{-12}$ parts of the central frequency using multiheterodyne self-detection. This new harmonic comb state extends the range of applications of quantum cascade laser frequency combs.

physics.optics↗

arXiv2015

On-chip Dual-comb based on Quantum Cascade Laser Frequency Combs

Dual-comb spectroscopy is emerging as one of the most appealing applications of mid-infrared frequency combs for high-resolution molecular spectroscopy, as it leverages on the unique coherence properties of frequency combs combined with the high sensitivities achievable by mid-infrared molecular spectroscopy. Here we present an on-chip dual-comb source based on mid-infrared quantum cascade laser frequency combs, where two frequency combs are integrated on a single chip. Control of the combs repetition and offset frequencies is obtained by integrating micro-heaters next to each laser. We show that a full control of the dual-comb system is possible, by measuring a multi-heterodyne beating corresponding to an optical bandwidth of 32 cm$^{-1}$ at a center frequency of 1330 cm$^{-1}$ (7.52 $μ$m), demonstrating that this device is ideal for compact dual-comb spectroscopy systems.

physics.optics↗

arXiv2015

Dispersion engineering of Quantum Cascade Lasers frequency combs

Quantum cascade lasers are compact sources capable of generating frequency combs. Yet key characteristics - such as optical bandwidth and power-per-mode distribution - have to be improved for better addressing spectroscopy applications. Group delay dispersion plays an important role in the comb formation. In this work, we demonstrate that a dispersion compensation scheme based on a Gires-Tournois Interferometer integrated into the QCL-comb dramatically improves the comb operation regime, preventing the formation of high-phase noise regimes previously observed. The continuous-wave output power of these combs is typically $>$ 100 mW with optical spectra centered at 1330 cm$^{-1}$ (7.52 $μ$m) with $\sim$ 70 cm$^{-1}$ of optical bandwidth. Our findings demonstrate that QCL-combs are ideal sources for chip-based frequency comb spectroscopy systems.

physics.optics↗

arXiv2014

The Higgs Boson is found: What is next?

The situation in particle physics after the discovery of the Higgs boson is discussed. Is the Standard Model complete? Are there still mysteries which have no answer? Answering these questions we consider the Higgs sector, the neutrino sector and the flavor sector of the Standard Model, and list the problems which are still far from understanding. Going beyond the Standard Model we consider the Dark matter in the Universe and possible existence of new particles and interactions. The main attention is paid to supersymmetry. The problems faced by elementary particle physics in the near perspective are formulated.

hep-ph↗