arXiv subjects

Martin Virte

Publications and source records attributed to Martin Virte.

At least 19 recordsLinked to original sources

arXiv2026

Polarization Dynamics in VCSELs Under Sinusoidal Signal Modulation around the Polarization Switching point

Vertical-Cavity Surface-Emitting Lasers (VCSELs) combine compact geometry, low threshold current, and ease of integration, making them central to modern photonic systems. However, their polarization behavior remains a critical factor affecting performance, as the emission state can switch between orthogonally polarized modes around the so-called polarization switching point. This regime exhibits high sensitivity, where small perturbations induce abrupt polarization changes and nonlinear responses. In this work, the polarization dynamics of VCSELs under sinusoidal current modulation around the switching point are numerically investigated using the Spin-Flip Model. The study examines the influence of modulation frequency, amplitude, and bias current, revealing distinct dynamical regimes including polarization locking, periodic and irregular switching. The observed transitions between regimes elucidate the interplay between modulation and polarization stability, providing insight into the control of VCSEL dynamics for high-speed optical communication and sensing applications.

physics.optics↗

arXiv2026

Nanosecond-scale discrete wavelength switching in feedback-controlled single-gain-section multi-wavelength lasers

We investigate discrete wavelength switching in single-gain-section multi-wavelength lasers monolithically integrated on InP with phase-controlled optical-feedback. By modulating the feedback phase, nanosecond-scale wavelength switching is experimentally demonstrated with transition times below 2.5 ns. Measurements consistently show that the switching time decreases with stronger optical feedback and larger phase-modulation amplitudes. Transitions from lower to higher modal gain are faster. We support the experimental observations with a multi-mode extension of the Lang-Kobayashi rate-equation model. We analyze the influence of laser, feedback-cavity, and modulation parameters on the switching dynamics, and highlight the role of mode coupling. These results highlight the potential of integrated multi-wavelength lasers for compact and high-speed all-optical networking systems.

physics.optics↗

arXiv2025

Theoretical analysis of optical feedback-controlled emission of dual-wavelength lasers

Dual and multi-wavelength lasers, i.e., lasers with the ability to emit at two or more wavelengths in a controlled fashion, represent an exciting new twist in laser physics. Harnessing the mode competition to control them better remains, however, a challenge. In this work, we numerically explore the effect of optical feedback on the emission properties of a dual-wavelength laser using a rate equation model. We focus on switching capability and investigate the impact of key laser and feedback parameters. We connect the emergence of simultaneous emission to a lower cross-saturation between modes, and demonstrate that robust switching can be achieved using a short feedback cavity and a sufficiently strong feedback. In particular and in contrast to previous publications, we highlight that the feedback phase difference between the two modes is not a critical parameter. Our results are consistent with recent experimental observations, supporting the relevance of feedback-based control techniques for multi-wavelength lasers.

physics.optics↗

arXiv2025

Agile and Broadband All-Optical Wavelength Conversion with Multi-Wavelength Lasers

We demonstrate a novel approach to all-optical wavelength conversion (AOWC) using a monolithically integrated InP multi-wavelength laser (MWL). By exploiting carrier-induced gain modulation and intermodal coupling within the common gain section, we achieve data wavelength conversion over a 1.3 THz range for signals up to 10 GBd, without the need for an external probe laser. The scheme relies on optical injection of the data signal into the MWL, where strong mode coupling enables transfer of the modulation to other longitudinal modes. A monolithically integrated feedback cavity provides agile switching between three longitudinal modes or even broadcasting across the three channels by adjusting the feedback phase. We evaluate the signal quality of the converted data through BER measurements for various symbol rates, showing both transparent conversion and, at low injection powers, even net signal gain. Complementary numerical simulations, based on a multimode extension of the Lang-Kobayashi rate equations, reveal the role of modal gain imbalance and cross-saturation in shaping the conversion efficiency. These results establish a scalable, compact, and energy-efficient route toward agile AOWC devices.

physics.optics↗

arXiv2025

Agile laser wavelength tuning using dynamic targeting

Tunable lasers are essential and versatile tools in photonics, with applications spanning telecommunications, spectroscopy, and sensing. Advancements have aimed to expand tuning ranges, suppress mode hopping, and enable photonic integration. In this work, we explore the adaptation of dynamic targeting, a technique originally developed to stabilize lasers under optical feedback, as a method for achieving agile, fast, and continuous wavelength tuning. By adjusting the feedback rate and phase, we enable a stable and controlled frequency shift. We experimentally demonstrate reliable and reproducible tuning over 2.1 GHz using a free-space optical setup. Simulations further suggest that this approach could extend the tuning range to tens of GHz, with a potential scan speed exceeding $10^{17}$ Hz/s. These results highlight dynamic targeting as a promising route toward agile frequency control in semiconductor lasers.

physics.optics↗

arXiv2024

Response of a multi-wavelength laser to single-sideband optical injection

Single-mode semiconductor lasers subject to optical injection have been shown to trigger a wide range of dynamical behavior from injection locking to chaos. Multi-wavelength lasers add even more degrees of freedom and complexity to the dynamical repertoire potentially unlocking new functionalities for applications ranging from THz generation and processing to all-optical memories. In particular, leveraging the inherent mode coupling in multi-wavelength lasers, spectral multiplication over a THz range of an injected optical signal has been shown. While most of the research on optical injection has been focused on single-mode semiconductor lasers, the dynamical behavior of multi-wavelength lasers, particularly when subjected to injection of amplitude-modulated signals remains vastly unexplored. In this work, we numerically and experimentally investigate the response of an on-chip dual-wavelength laser subject to the optical injection of a single-sideband signal around one of the modes of the laser. Our findings show an asymmetric power evolution of the sidebands appearing around both the injected and un-injected modes with respect to the modulation frequency. The power and bandwidth of the sideband signals strongly depend on the resonance frequency produced by the interference between the cavity mode and the injection, which can be tailored by twerking the strength and the detuning of the injection. The outcomes of our numerical investigations, based on rate equations, align closely with the experimental results highlighting the influence of key injection and laser parameters.

physics.optics↗

arXiv2024

Wavelength tuning of VCSELs via controlled strain

Besides major advantages for telecommunication applications, VCSELs have attracted interest for their potential for neuro-inspired computing, frequency comb generation or high-frequency spin oscillations. In the meantime, strain applied to the laser structure has been shown to have a significant impact on the laser emission properties such as the polarization dynamics or birefringence. In this work, we further explore the influence of strain on VCSELs and how this effect could be used to fine tune the laser wavelength. Through a comprehensive investigation, we demonstrate consistent wavelength shift up to 1 nm and report a sensitivity between 0.12 to 0.18 nm / millistrain. We also record birefringence values up to 292 GHz. Our results show that controlled strain level could be considered for fine wavelength tuning and possibly alleviate the selection of VCSEL for precise wavelength requirements.

physics.optics↗

arXiv2023

Influence of Feedback Phase on Time Delay Signature and Chaos Bandwidth in a Laser subject to Dual Optical Feedback

Semiconductor lasers subject to optical feedback can behave chaotically, which can be used as a source of randomness. The optical feedback, provided by mirrors at a distance, determines the characteristics of the chaos and thus the quality of the randomness. However, this fixed distance also shows itself in the intensity, an unwanted feature called the Time Delay Signature (TDS). One promising solution to suppress the TDS is using double optical feedback. We study this system numerically in this paper. In particular, we focus on the impact of the feedback phase, a sub-wavelength change in the position of the mirrors, on the TDS and chaos bandwidth (CBW) of the system. We show that by precisely setting the feedback parameters, including the feedback phases, the TDS can be suppressed, and that the feedback phase control is necessary rather than optional to robustly suppress the TDS. In addition, it is possible to suppress the TDS without loss of the CBW. At strong feedback rates the system can restabilize, and one can switch between a chaotic and steady state by changing only the feedback phase. Finally, we relate the feedback phase sensitivity to interference between the two delayed signals. This system is promising for applications of chaotic lasers as one can either suppress the TDS or increase the CBW.

physics.optics↗

arXiv2023

Impact of feedback time-distribution on laser dynamics

Time-distributed optical feedback in semiconductor lasers has gained attention for its ability to produce high-quality chaos and effectively suppress the time-delay signature. However, the fundamental impact of the distribution of feedback in time on laser dynamics remains unexplored. In this paper, we investigate this topic by using fiber Bragg grating (FBG) feedback. We theoretically study the laser response using FBGs of different lengths but similar reflectivity, effectively stretching the impulse response over a longer period while maintaining its overall shape. We observe that above a critical value corresponding to a grating length of approximately $1$\,cm, fluctuations in laser stability emerge. We attribute this phenomenon to the damping of relaxation oscillations when the zeros of the FBG reflectivity spectrum align with the laser side lobes around the relaxation oscillation frequency. We also uncover an asymmetrical dynamical behavior of the laser for positive and negative frequency detuning. We deduce that this asymmetry is a characteristic feature of FBG feedback and delve into the specificities that trigger such behavior.

physics.optics↗

arXiv2023

Clarifying the impact of dual optical feedback on semiconductor lasers through analysis of the effective feedback phase

Time-delayed optical feedback is known to trigger a wide variety of complex dynamical behavior in semiconductor lasers. Adding a second optical feedback loop is naturally expected to further increase the complexity of the system and its dynamics, but due to interference between the two feedback arms it was also quickly identified as a way to improve the laser stability. While these two aspects have already been investigated, the influence of the feedback phases, i.e. sub-wavelength changes in the mirror positions, on the laser behavior still remains to be thoroughly studied, despite indications that this parameter could have a significant impact. Here, we analyze the effect of the feedback phase on the laser stability in a dual-feedback configuration. We show an increased sensitivity of the laser system to feedback phase changes when two feedback loops are present, and clarify the interplay between the frequency shift induced by the feedback and the interferometric effect between the two feedback arms.

physics.optics↗

arXiv2022

Performance and control strategy of an integrated tunable laser with a single intra-cavity AMZI filter

Asymmetric Mach-Zehnder interferometers (AMZIs) can, in principle, enable continuous wavelength tuning of a laser when used as an intra-cavity filter. Their simplicity and good compatibility with generic foundry platforms are major advantages. However, the difficulty to develop a well-defined and robust control strategy is an important drawback which restricts the use-cases of these tunable lasers. Here, we make an in-depth investigation of the tunability properties of a laser including a single-stage AMZI in its cavity. We find that due to imperfections of Electro-Optic Phase Modulators (EOPMs), the dependence of the phase variation with the applied voltage is not linear. Because integrated EOPMs cannot be individually calibrated, these nonlinearities prevent a precise and independent tuning of the phase and amplitude of the AMZI transfer function, and thus continuous tuning cannot be reliably achieved. To overcome this issue, we propose a refined control strategy which allows for semi-continuous tuning. With this approach, we demonstrate a piece-wise continuous tuning of the emission wavelength by taking advantage of the coupling between amplitude and phase in the AMZI response. With our refined control strategy, we achieve tuning of the emission wavelength over the full free spectral range (FSR) of the AMZI.

physics.optics↗

arXiv2022

Chaotic time-delay signature suppression in lasers using phase-controlled dual optical feedback

We experimentally study a semiconductor laser subject to two optical feedbacks in a free space setup. We show that the time delay signature, manifesting itself in the chaotic output intensity, can be better suppressed than in a laser with single feedback. We demonstrate that the control of the feedback phase is essential to suppress the time delay signature, in contrast to the one-delay case, and that the feedback phase also impacts the chaotic bandwidth. By optimizing the feedback phase the time delay signature can be reduced by a factor of 2 while maintaining a large chaotic bandwidth.

physics.optics↗

arXiv2022

Control of dual-wavelength laser emission via optical feedback phase tuning

We propose and demonstrate a technique to control the balance between the two amplitudes of a dual-wavelength laser based on a phase-controlled optical feedback. The feedback cavity length is adjusted to achieve a relative phase shift between the desired emission wavelengths, introducing a boost in gain for one wavelength while the other wavelength experiences additional losses. Tuning the optical feedback phase proves to be an effective way to control the gain and losses, and, thus, to select one or balance the amplitude of the two emission wavelengths. This concept can be easily adapted to any platform, wavelength range and wavelength separations providing that a sufficient carrier coupling and gain can be obtained for each mode. To demonstrate the feasibility and to evaluate the performance of this approach, we have implemented two dual-wavelength lasers with different spectral separations together with individual optical feedback loops onto a InP generic foundry platform emitting around 1550 nm. An electro-optical-phase-modulator is used to tune the feedback phase. With this single control parameter, we successfully achieved extinction ratios of up to 38.6 dB for a 10 nm wavelength separation and up to 49 dB for a 1 nm wavelength separation.

physics.optics↗

arXiv2022

Mode-coupling effects in an optically-injected dual-wavelength laser

Lasers designed to emit at multiple and controllable modes, or multi-wavelength lasers, have the potential to become key building blocks for future microwave photonic technologies. While many interesting schemes relying on optical injection have been proposed, the nonlinear mode coupling between different modes of a multi-wavelength laser and their dynamical behavior under optical injection remains vastly unexplored. Here, we experimentally and numerically study the effect of optical injection around the suppressed mode of a dual12 wavelength laser and the resulting interactions with the dominant mode. We highlight a wavelength shift of the dominant mode triggered by injection locking of the suppressed mode and report a strong impact of the mode suppression ratio on the locking range. Finally, we show numerically that the cross-coupling parameter between the two modes might have a key role in this effect.

physics.optics↗

arXiv2022

Impact of FBG feedback phase on laser dynamics

Fiber Bragg Gratings have been advantageously used to improve the chaotic properties of semiconductor lasers. Though these components are known to be highly sensitive to environmental conditions, feedback phase fluctuations are often neglected. In this work, we experimentally demonstrate that the small variations of the propagation time induced by a simple thermal tuning of the FBG is sufficient to induce significant changes of the laser behavior. We report periodic stability enhancements linked with phase variations and highlight that both phase variation and phase offsets play an important role. Last, we show a good qualitative agreement with simulations based on an expanded version of the Lang-Kobayashi model.

physics.optics↗

arXiv2021

Chaotic time-delay signature suppression using quantum noise

Time-delay signature (TDS) suppression of semiconductor lasers with external optical feedback is necessary to ensure the security of chaos-based secure communications. Here we numerically and experimentally demonstrate a technique to effectively suppress the TDS of chaotic lasers using quantum noise. The TDS and dynamical complexity are quantified using the autocorrelation function and normalized permutation entropy at the feedback delay time, respectively. Quantum noise from quadrature fluctuations of vacuum state is prepared through balanced homodyne measurement. The effects of strength and bandwidth of quantum noise on chaotic TDS suppression and complexity enhancement are investigated numerically and experimentally. Compared to the original dynamics, the TDS of this quantum-noise improved chaos is suppressed up to 94% and the bandwidth suppression ratio of quantum noise to chaotic laser is 1:25. The experiment agrees well with the theory. The improved chaotic laser is potentially beneficial to chaos-based random number generation and secure communication.

quant-ph↗

arXiv2019

Dual-wavelength lasers on generic foundry platform

We propose and implement four simple and compact dual-wavelength laser concepts integrated in a Photonic Integrated Circuit (PIC) based on a InP generic foundry platform. In a first step, we arrange two detuned Distributed-Bragg-Reflectors (DBR) in either a sequential or in a parallel order, acting as narrowband wavelength selective cavity mirrors. In a second step, we close the cavities by using either a third DBR or by using a Multimode-Interference-Reflector (MIR). We present LI-characteristics and optical spectra emitting around 1550~nm with wavelength separations of 1~nm or 10~nm and evaluate their particular potential for simultaneous dual-wavelength emission. In addition, we find either one or multiple equal power points as well as complete switches when the gain current is being tuned. We discuss the characteristics and limitations of each concept including arranging the detuned DBRs in a sequential or parallel order.

physics.app-ph↗

arXiv2019

Evaluating entropy rate of laser chaos and shot noise

Evaluating entropy rate of high-dimensional chaos and shot noise from analog raw signals remains elusive and important in information security. We experimentally present an accurate assessment of entropy rate for physical process randomness. The entropy generation of optical-feedback laser chaos and physical randomness limit from shot noise are quantified and unambiguously discriminated using the growth rate of average permutation entropy value in memory time. The permutation entropy difference of filtered laser chaos with varying embedding delay time is investigated experimentally and theoretically. High resolution maps of the entropy difference is observed over the range of the injection-feedback parameter space. We also clarify an inverse relationship between the entropy rate and time delay signature of laser chaos over a wide range of parameters. Compared to the original chaos, the time delay signature is suppressed up to 95% with the minimum of 0.015 via frequency-band extractor, and the experiment agrees well with the theory. Our system provides a commendable entropy evaluation and source for physical random number generation.

physics.optics↗