Laser-trigged high-voltage switches are used in many applications, including pulsed power machines, where the trigger performance is important. Here we use Particle-In-Cell Monte Carlo (PIC-DSMC) plasma model coupled with a quantum mechanical model of the laser-material interaction to simulate the discharge process due to an incident laser pulse on an electrode [1]. In the present work we design the electrode as a metasurface and simulate the incident laser's spatially varying intensity. The local laser intensity is used in the light-material interaction model to generate a spatially varying boundary condition for the electron emission current and electrode vaporization for a given laser power. We will present 3D simulations of the plasma evolution and compare the properties of the switch closure (current conduction) between the metasurface case and a normal electrode for a range of laser energies.

This paper presents an ultra-high-coherence quantum-dot laser grown on a silicon substrate, achieving a record-breaking intrinsic linewidth of 16 Hz. This approach is compatible with low-Q external cavities for linewidth reduction and integration with silicon photonics.

Recent studies have demonstrated that a laser can self-generate frequency combs when tuned near an exceptional point (EP), where two cavity modes coalesce. These EP combs induce periodic modulation of the population inversion in the gain medium, and their repetition rate is independent of the laser cavity's free spectral range. In this work, we perform a stability analysis that reveals two notable properties of EP combs, bi-stability and a period-doubling cascade. The period-doubling cascade enables halving of the repetition rate while maintaining the comb's total bandwidth, presenting opportunities for the design of highly compact frequency comb generators.

We numerically investigate the generation of nonclassical light in semiconductor micropillar cavities containing quantum dots (QDs), focusing on quadrature squeezing. Using cavity-QED, equations of motion are derived for an inhomogeneously broadened QD distribution that is incoherently excited and subjected to an injected seed laser field. Steady-state solutions are obtained and used to determine the quadrature variances. We identify a narrow parameter regime below the lasing threshold where squeezing emerges in the amplitude quadrature, with variances falling below the vacuum limit.

Ultra-low-noise laser sources are crucial for a variety of applications, including microwave synthesizers, optical gyroscopes, and the manipulation of quantum systems. Silicon photonics has emerged as a promising solution for high-coherence applications due to its ability to reduce system size, weight, power consumption, and cost (SWaP-C). Semiconductor lasers based on self-injection locking (SIL) have reached fiber laser coherence, but typically require a high-Q external cavity to suppress coherence collapse through frequency-selective feedback. Lasers based on external-cavity locking (ECL) are a low-cost and turnkey operation option, but their coherence is generally inferior to SIL lasers. In this work, we demonstrate quantum-dot (QD) lasers grown directly on Si that achieve SIL laser coherence under turnkey ECL. The high-performance QD laser offers a scalable and low-cost heteroepitaxial integration platform. Moreover, the QD laser's chaos-free nature enables a 16 Hz Lorentzian linewidth under ECL using a low-Q external cavity, and improves the frequency noise by an additional order of magnitude compared to conventional quantum-well lasers.

This paper explores the impact of gain medium on linewidth narrowing in integrated self-injection locked III–V/SiN lasers, theoretically and experimentally. We focus on the effects of carrier densities of states in zero- and two-dimensional structures due to quantum-dot and quantum-well confinement. The theoretical approach includes (a) multimode laser interaction to treat mode competition and wave mixing, (b) quantum-optical contributions from spontaneous emission, and (c) composite laser/free-space eigenmodes to describe outcoupling and coupling among components within an extended cavity. For single-cavity lasers, such as distributed feedback lasers, the model reproduces the experimentally observed better linewidth performance of quantum-dot active regions over quantum-well ones. When applied to integrated III–V/SiN lasers, our analysis indicates Hz-level linewidth performance for both quantum-dot and quantum-well gain media due to overcoming the difference in carrier-induced refractive index by incorporating a high-Q SiN passive resonator. Trade-offs are also explored between linewidth, output power, and threshold current.

We compare self-injection locking and external cavity locking for linewidth reduction in semiconductor lasers with varying linewidth enhancement factors (LEF5). Results indicate the optimal narrowing technique is determined by the specific LEF of the laser. (c) 2024 The Author(s)

This paper reports on an investigation of the frequency-modulated comb operation in a quantum-dot laser. Both the amplitude-modulated and the frequency-modulated combs can be generated independently from the same device through bias and the engineering of the optical nonlinearities.

Narrow-linewidth lasers are essential across a wide range of applications, including classical and quantum sensing, trapped ion systems, position/navigation/timing systems, optical clocks, and microwave frequency synthesizers. In the visible and near-visible spectrum, low-noise lasers are particularly important for laser trapping and cooling techniques, which are vital for trapped ion quantum computing, sensing, and atomic clocks. In this context, our work showcases a hybrid-integrated narrow-linewidth laser that operates at 780 nm, achieving a self-heterodyne linewidth of 105 Hz. To validate the experimental results, we performed a numerical analysis that combines insights from a many-body theory applied to the gain region with a travelling-wave model to capture the laser dynamics. Our investigation further delves into how the linewidth of the self-injection locked lasers is influenced by the parameters of micro-ring resonators, aiming to assess the potential for achieving Hz-level integrated laser linewidths at 780 nm. This work not only demonstrates the technical feasibility of Hz-level narrow-linewidth lasers but also lays the groundwork for future explorations in the field.

Stable laser emission with narrow linewidth is of critical importance in many applications, including coherent communications, LIDAR, and remote sensing. In this work, the physics underlying spectral narrowing of self-injection-locked on-chip lasers to Hz-level lasing linewidth is investigated using a composite-cavity structure. Heterogeneously integrated III-V/SiN lasers operating with quantum-dot and quantum-well active regions are analyzed with a focus on the effects of carrier quantum confinement. The intrinsic differences are associated with gain saturation and carrier-induced refractive index, which are directly connected with 0- and 2-dimensional carrier densities of states. Results from parametric studies are presented for tradeoffs involved with tailoring the linewidth, output power, and injection current for different device configurations. Though both quantum-well and quantum-dot devices show similar linewidth-narrowing capabilities, the former emits at a higher optical power in the self-injection-locked state, while the latter is more energy-efficient. Lastly, a multi-objective optimization analysis is provided to optimize the operation and design parameters. For the quantum-well laser, minimizing the number of quantum-well layers is found to decrease the threshold current without significantly reducing the output power. For the quantum-dot laser, increasing the quantum-dot layers or density in each layer increases the output power without significantly increasing the threshold current. These findings serve to guide more detailed parametric studies to produce timely results for engineering design.

We describe investigations on quantum fluctuations in semiconductor lasers relating to a lineshape anomaly while lasing at the spontaneous-emission limit. Measurements show an emerging Gaussian component, contradicting the cavity-QED predicted Lorentzian lineshape. Theoretical studies indicate an intrinsic contribution from intricate cavity-outcoupling and active-medium nonlinearity interplay.

Quantum dot lasers are an attractive option for light sources in silicon photonic integrated circuits. Thanks to the three-dimensional charge carrier confinement in quantum dots, high material gain, low noise and large temperature stability can be achieved. This paper discusses, both theoretically and experimentally, the advantages of silicon-based quantum dot lasers for passive mode-locking applications. Using a frequency domain approach, i.e., with the laser electric field described in terms of a superposition of passive cavity eigenmodes, a precise quantitative description of the conditions for frequency comb and pulse train formation is supported, along with a concise explanation of the progression to mode locking via Adler’s equation. The path to transform-limited performance is discussed and compared to the experimental beat-note spectrum and mode-locked pulse generation. A theory/experiment comparison is also used to extract the experimental group velocity dispersion, which is a key obstacle to transform-limited performance. Finally, the linewidth enhancement contribution to the group velocity dispersion is investigated. For passively mode-locked quantum dot lasers directly grown on silicon, our experimental and theoretical investigations provide a self-consistent accounting of the multimode interactions giving rise to the locking mechanism, gain saturation, mode competition and carrier-induced refractive index.

This work compares the four-wave mixing (FWM) effect in epitaxial quantum dot (QD) lasers grown on silicon with quantum well (QW) lasers. A comparison of theory and experiment results shows that the measured FWM coefficient is in good agreement with theoretical predictions. The gain in signal power is higher for p-doped QD lasers than for undoped lasers, despite the same FWM coefficient. Owing to the near-zero linewidth enhancement factor, QD lasers exhibit FWM coefficients and conversion efficiency that are more than one order of magnitude higher than those of QW lasers. Thus, this leads to self-mode locking in QD lasers. These findings are useful for developing on-chip sources for photonic integrated circuits on silicon.

In this work we present a microscopic theory based on a cavity QED semiconductor model to investigate the emission of InGaAsP-based metallic cavity nanolasers. The consistent approach of modelling the interplay of quantum optical and semiconductor effects allows for excellent agreement with pump-power dependant experimental results.

Abstract This paper describes an analysis of integrated III-V/SiN lasers operating with quantum-dot and quantum-well active regions. We focus on the effects of 0- and 2-dimensional carrier densities of states on linewidth narrowing. The theoretical approach includes a) multimode laser interaction to treat mode competition and wave mixing, b) quantum-optical contributions from spontaneous emission and c) composite laser/free-space eigenmodes to describe outcoupling and coupling among components within an extended cavity. The approach is able to describe the progression to Hz-level lasing linewidth observed in III-V/SiN lasers with quantum-dot active regions. In addition, it predicts that the integration of III-V/SiN mitigates the high quantum-well linewidth enhancement factor, resulting in similar Hz-level linewidth performance. Tradeoffs are explored among linewidth, output power and injection current.

This paper describes a calculation of the spontaneous emission limited linewidth of a semiconductor laser consisting of hybrid or heterogeneously integrated, silicon and III-V intracavity components. Central to the approach are a) description of the multi-element laser cavity in terms of composite laser/free-space eigenmodes, b) use of multimode laser theory to treat mode competition and multiwave mixing, and c) incorporation of quantum-optical contributions to account for spontaneous emission effects. Application of the model is illustrated for the case of linewidth narrowing in an InAs quantum-dot laser coupled to a high-Q SiN cavity.

Epitaxially grown quantum dot (QD) lasers are emerging as an economical approach to obtain on-chip light sources. Thanks to the three-dimensional confinement of carriers, QDs show greatly improved tolerance to defects and promise other advantages such as low transparency current density, high temperature operation, isolator-free operation, and enhanced four-wave-mixing. These material properties distinguish them from traditional III-V/Si quantum wells (QWs) and have spawned intense interest to explore a full set of photonic integration using epitaxial growth technology. We present here a summary of the most recent developments of QD lasers grown on a CMOS-compatible (001) Si substrate, with a focus on breakthroughs in long lifetime at elevated temperatures. Threading dislocations are significantly reduced to the level of 1 x 10(6) cm(-2) via a novel asymmetric step-graded filter. Misfit dislocations are efficiently blocked from the QD region through well-engineered trapping layers. A record-breaking extrapolated lifetime of more than 200000 hours has been achieved at 80 degrees C, forecasting that device reliability is now entering the realm of commercial relevance and a monolithically integrated light source is finally on the horizon.