Papers by Mikhail Maximov
Thermal resistance measurement of edge-emitting semiconductor lasers using spontaneous emission spectra
Fizika i tehnika poluprovodnikov, 2022
An improved technique for thermal resistance measurement of edge-emitting diode lasers using spon... more An improved technique for thermal resistance measurement of edge-emitting diode lasers using spontaneous emission spectra, collected through the opening in the n-contact within the range of operating currents, has been proposed. The advantage of the proposed technique is that systematic errors typical for measurements based on lasing spectra are excluded. The accuracy of the method was verified by measuring the dependence of the thermal resistance on the cavity length for diode lasers with 100 μm strip width. Obtained results are in good agreement with the model, and the minimum measurement error was ±0.1 K/W. The proposed technique can be used in metrological support of fabrication process of semiconductor lasers. Keywords: laser diode, thermal resistance, spontaneous emission.
Pisʹma v Žurnal tehničeskoj fiziki, 2022
We studied the influence of the focused ion beam milling of ridge waveguides on lasing parameters... more We studied the influence of the focused ion beam milling of ridge waveguides on lasing parameters of edgeemitting lasers, based on a separate confinement double heterostructure. It is shown that there are three degrees of influence, according to the etching depth: modification of the waveguide properties only, a decrease in efficiency without changing the threshold current, and a simultaneous deterioration in the threshold current and efficiency with significant modification of the optical characteristics of the laser.
Pisʹma v Žurnal tehničeskoj fiziki, 2023
We propose an approach for encoding and transmitting information based on the use of a quantum do... more We propose an approach for encoding and transmitting information based on the use of a quantum dot laser, which, depending on the injection current, emits either one of two or simultaneously two spectral components, with different wavelengths. When the laser is modulated by current, each lasing line is detected by an independent photodiode, and thus the information is encoded by both the intensity of each line and its wavelength.
Information Encoding Using Two-Level Generation in a Quantum Dot Laser
Technical physics letters, Dec 1, 2023
We propose an approach for encoding and transmitting information based on the use of a quantum do... more We propose an approach for encoding and transmitting information based on the use of a quantum dot laser, which, depending on the injection current, emits either one of two or simultaneously two spectral components, with different wavelengths. When the laser is modulated by current, each lasing line is detected by an independent photodiode, and thus the information is encoded by both the intensity of each line and its wavelength. Keywords: quantum dot lasers, two-state lasing, multilevel signaling, wavelength- division multiplexing.
Lateral Mode Tuning in Coupled Ridge Waveguides Using Focused Ion Beam
Semiconductors, Dec 1, 2020
We present an approach for the treatment of coupled-ridge lasers using focused ion beam (FIB) et... more We present an approach for the treatment of coupled-ridge lasers using focused ion beam (FIB) etching. We show experimentally that the FIB etching allows post-processing lateral mode tuning without deterioration of the main laser parameters.
Broadband Superluminescent Diodes Based on Multiple InGaAs/GaAs Quantum Well-Dot Layers
Semiconductors, Dec 1, 2023
Microdisk lasers for high sensitive protein detection in microfluidic devices (Conference Presentation)
Biophotonics in Point-of-Care, Apr 1, 2020
Lasers based on semiconductor whispering gallery mode (WGM) resonators represent a perfect platfo... more Lasers based on semiconductor whispering gallery mode (WGM) resonators represent a perfect platform for active small footprint high-sensitive devices for biodetection. Biochemical samples typically require aqueous solution, and the resonator should be placed into a cuvette with water or in a microfluidic chip. The characteristics of modern semiconductor WGM lasers with an active region based on InAs/InGaAs quantum dots (QDs) make them promising for creating compact highly sensitive devices for biodetection. Deep localization of carriers in InAs/InGaAs QDs and suppressed lateral migration helps us to obtain room-temperature lasing in microdisk lasers immersed in an aqueous medium. In this work, we studied the sensitivity of the microdisk laser resonance spectral position to the refractive index of the surrounding material by changing the salinity of the water solution. We also successfully detected model proteins (secondary antibodies attached to the microdisk surface) via measurement of the lasing threshold power. The proteinprotein interaction on the microdisk surface manifests itself by an increase in the laser threshold power. Thus, in this work we demonstrated, for the first time, the possibility of using QD semiconductor microdisk lasers for detection of proteins in a microfluidic device.
Physica Scripta
We suggest an idea of data encoding scheme based on the switching from the ground state (GS) to e... more We suggest an idea of data encoding scheme based on the switching from the ground state (GS) to excited state (ES) lasing in quantum dot (QD) lasers with increase in injection current. The groups of two bits are assigned to lasing spectra that comprise either one or both GS and/or ES lasing lines depending on injection current. We expect that the proposed encoding scheme can potentially combine some advantages of multilevel signaling and wavelength division multiplexing.
Optoelectronic devices with active region based on InGaAs/GaAs quantum well dots
Semiconductor Lasers and Laser Dynamics IX
We report on broad-area lasers, mode-locked lasers (MLLs), and superluminescent light-emitting di... more We report on broad-area lasers, mode-locked lasers (MLLs), and superluminescent light-emitting diodes (SLDs) based on a recently developed novel type of nanostructures that we refer to as quantum well-dots (QWDs). The QWDs are intermediate in properties between quantum wells and quantum dots and combine some useful properties of both. 1.08 μm InGaAs/GaAs QWDs broad area edge-emitting lasers based on coupled large optical cavity waveguides show high internal quantum efficiency of 92%, low internal loss of 0.9 cm-1 and material gain of ~1.1∙104 cm-1 per one QWD layer. CW output power of 14.2 W is demonstrated at room temperature. Superluminescent light-emitting diodes with one QWD layer in the active region exhibit stimulated emission spectra centered at 1050 nm with the maximal full width at half maximum of 36 nm and the output power of 17 mW. First results on mode-locked operation in QWD lasers are also presented. 2 mm long two-section devices demonstrate the pulse repetition rate of 19.3 GHz and the pulse duration of 3.5 ps. The width of the radio frequency spectrum is 0.2 MHz.
Characteristics of Injection Microdisk Lasers with InGaAs/GaAs Quantum Well-Dots
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
Quantum dot (QD) based microdisk/microring lasers have attracted attention as promising candidate... more Quantum dot (QD) based microdisk/microring lasers have attracted attention as promising candidates for on-chip optical interconnects since they offer small footprint, high-temperature stability and in-plane light emission. An important property required for a laser intended for optical communication is high-frequency direct modulation. Edge emitting QD-based lasers on GaAs demonstrated promising modulation characteristics with a − 3 dB modulation bandwidth in excess of 7.4 GHz [1]. Meanwhile, there are practically no reports on the dynamic characteristics of QD-based microdisk/microring lasers.
III–V microdisk/microring resonators and injection microlasers
Journal of Physics D: Applied Physics, 2021
Semiconductor whispering-gallery-mode (WGM) microresonators are promising candidates for creating... more Semiconductor whispering-gallery-mode (WGM) microresonators are promising candidates for creating compact, energy-efficient light sources (microlasers) for various applications owing to their small footprints, high Q factors, planar geometry, in-plane light emission, and high sensitivity to the environment. In this review we present the most recent advances in III–V microdisk/microring lasers. We briefly describe basic physics behind photonic WGM resonators and discuss different designs of III–V microdisk/microring lasers. We focus on the technological key points of the different approaches to realize efficient optical and carrier confinement in the laser cavity. Advantages and disadvantages of various types of the laser active region, i.e. quantum well (QW) and quantum dots, are discussed. We also report on successful fabrication of microlasers with gain medium of mixed dimensionality, so called QW-dots, which is promising for low-threshold, temperature insensitive and high output power operation. We summarized and systematically compare the characteristics of electrically driven microlasers. We address one major shortcoming for the circular WGM lasers, which is that the lasing emission is non-directional and non-homogeneous along the cavity rim. High quality factor of the resonator modes and circular symmetry lead to difficulties in obtaining the directional light output and in obtaining significant levels of the output optical power. We compared various techniques for realizing unidirectional emission or coupling to a waveguide. We also discuss high-speed direct modulation, which is another crucial characteristic for the microlasers. We also address energy consumption characteristics of the WGM microlasers under direct modulation and possibilities of energy-to-data ratio minimization. Finally, we summarize the prospects for the WGM lasers and their role in future applications in communications and sensing.
Highly efficient edge-emitting and microdisk lasers based on quantum well-dots (Conference Presentation)
Small-signal modulation and 10 Gb/s data transmission by microdisk lasers based on InGaAs/GaAs quantum well-dots
Semiconductor Lasers and Laser Dynamics IX, 2020
We show that using dense arrays of InGaAs quantum well-dots enables uncooled high-frequency appli... more We show that using dense arrays of InGaAs quantum well-dots enables uncooled high-frequency applications with a GHz-range bandwidth. A maximum 3-dB modulation frequency of about 6 GHz was found. The K-limited maximal frequency of 13 GHz was estimated from the modulation response analysis. The experimental values of the energy-todata reaches 1.5 pJ/bit for the smallest diameter under study (10 μm). A 23 μm in diameter microlaser exhibits open eye diagram up to 12.5 Gbit/s and is capable of error-free 10 Gbit/s data transmission at 30°C without temperature stabilization. Our results demonstrate the potential to achieve miniature high-speed on-chip light sources for optical communication applications using lasers with a diameter of only a few micrometers.
Effect of modulation p-doping level on multistate lasing in InAs/InGaAs quantum dot lasers having different external loss (Conference Presentation)
Semiconductor Lasers and Laser Dynamics VIII, 2018
Significant interest in compact InAs/InGaAs quantum dot (QD) lasers emitting near 1.3 mkm is caus... more Significant interest in compact InAs/InGaAs quantum dot (QD) lasers emitting near 1.3 mkm is caused by the diversity of their applications including non-invasive medicine and ultra-fast data transmission. In such lasers, lasing typically starts at the ground-state (GS) optical transitions of QDs. A further increase in injection may result in the appearance of an additional, short-wavelength spectral line associated with the excited-state (ES) optical transitions of QDs – a simultaneous lasing via QD GS and ES, i.e. multi-state lasing, takes place. The appearance of the ES-line may sufficiently affect the useful GS component. As injection current exceeds the multi-state lasing threshold, a decrease and even a complete quenching of GS-lasing may take place. As it was shown in [V.V. Korenev et. al, Appl. Phys. Lett. 102, 112101 (2013)], the usage of modulation p-doping has a positive influence on the hole concentration in QDs making GS-lasing quenching less pronounced. However, the influence of the concentration of p-dopant on multi-state lasing in general – and on the GS-lasing quenching in particular – has not been yet studied. To clarify this question experimentally, a series of InAs/InGaAs QD laser wafers was grown by molecular beam epitaxy. The active region of each sample was comprised of 10 layers of InAs/InGaAs QDs separated by 35 nm-thick GaAs spacers. Each spacer was p-doped into its central part of 10 nm using carbon atoms. Dependent on the sample, the carbon concentration was equal to 0, 3·10^17 cm^(-3), or 5·10^17 cm^(-3). A series of light-current curves corresponding to the GS component of output power was studied both theoretically and experimentally for “short” (0.5-mm-long) and for “long” (1.0-mm-long) samples. The experiment shows that in case of the short samples, the increase in p-doping level from 0 to 5·10^17 cm^(-3) results in the increase in maximum output power corresponding to the GS of QDs (WGS) from 0.8 to 2.2W, while in case of the longer samples the situation is opposite and WGS decreases from 4.5 to 3.7W correspondingly [V.V. Korenev et. al, Appl. Phys. Lett. 111, 132103 (2017)]. Qualitatively, such a discrepancy can be explained as follows. In case of the short samples, the higher p-doping level results in the faster hole capture into QDs mitigating the competition for the common holes between GS and ES optical transitions, which is an important reason for the GS-lasing quenching. In longer samples, optical loss is small and GS gain is far from its saturated value. Consequently, the ES energy level is weakly occupied and p-doping is not necessary to apply. However, even a small increment in the internal loss due to the p-dopant may lead to a noticeable decrease in laser`s differential efficiency. As a result, the higher p-doping level does not necessarily lead to the higher GS power as it was previously expected. However, if the sample is sufficiently short, the usage of modulation p-doping increases GS power. For a given cavity length, there is a certain p-doping level improving GS lasing characteristics.
Strain-Driven Phenomena upon Overgrowth of Quantum Dots: Activated Spinodal Decomposition and Defect Reduction
Quantum Dots: Fundamentals, Applications, and Frontiers
Strain-driven decomposition of an alloy layer is investigated as a means to control the structura... more Strain-driven decomposition of an alloy layer is investigated as a means to control the structural and electronic properties of self-organized quantum dots. Coherent InAs/GaAs islands overgrown with an InGaAs alloy layer serve as a model system. Cross-sectional and plan-view transmission electron microscopy, as well as photoluminescence studies, consistently indicate an increase in height and width of the quantum dots with increasing indium content and/or thickness of the alloy layer. The increase in dot size is attributed to the phase separation of the alloy layer driven by the surface strain introduced by the initial InAs islands. The density of large dislocated clusters in the quantum dot samples can be dramatically reduced by special in situ annealing (defect reduction) techniques. A laser based on multiple (up to 10) layers of InAs/GaAs quantum dots grown under optimized conditions with the use of defect reduction techniques show considerably enhanced optical gain and improved performance. Differential efficiency as high as 88% is achieved in the lasers. An emission wavelength of 1280 nm, a threshold current density of 147 A/cm2, a differential efficiency of 80%, and a characteristic temperature of 150 K are realized simultaneously in one device. Wavelength extension up to 1500 nm for InAs quantum dot lasers on GaAs substrates is possible by using metamorphic (plastically relaxed) buffer InGaAs layers. In cases when the threading dislocations are avoided in the active region, high-performance operation with quantum efficiency exceeding 60–70% and pulsed output powers up to 7 W are realized.
Improved performance of InGaAs/GaAs microdisk lasers epi-side down bonded onto a silicon board
Optics Letters, 2021
We study the impact of improved heat removal on the performance of InGaAs/GaAs microdisk lasers e... more We study the impact of improved heat removal on the performance of InGaAs/GaAs microdisk lasers epi-side down bonded onto a silicon substrate. Unlike the initial characteristics of microlasers on a GaAs substrate, the former’s bonding results in a decrease in thermal resistance by a factor of 2.3 (1.8) in microdisks with a diameter of 19 (31) µm, attributed to a thinner layered structure between the active region and the substrate and the better thermal conductivity of Si than GaAs. Bonded microdisk lasers show a 2.4–3.4-fold higher maximum output power, up to 21.7 mW, and an approximately 20% reduction in the threshold current. A record high 3 dB small-signal modulation bandwidth of 7.9 GHz for InGaAs/GaAs microdisk lasers is achieved.
Frequency response and carrier escape time of InGaAs quantum well-dots photodiode
Optics Express, 2021
p-i-n photodiodes comprising dense arrays of InGaAs quantum dots (referred to as quantum well-dot... more p-i-n photodiodes comprising dense arrays of InGaAs quantum dots (referred to as quantum well-dots) were fabricated, and the basic physical processes affecting their high-speed performance were studied for the first time by measuring the frequency response under illumination with photons absorbed either in the quantum well-dots (905-nm illumination) or mainly in GaAs layers (860-nm illumination). A GaAs p-i-n photodiode of similar design was also measured for comparison. A maximum −3 dB bandwidth of 8.2 GHz was measured for the 905-nm light illumination, and maximum internal −3 dB bandwidth of 12.5 GHz was estimated taking into account the effect of RC-parasitic by the equivalent circuit model. It was found that the internal response is mainly controlled by the carrier drift time in the depletion region; this process can be characterized by a field-dependent effective velocity of charge carriers in the layered heterostructure, which is approximately half the saturation velocity in G...
Hybrid integration of InAs/GaAs quantum dot microdisk lasers on silicon
2021 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), 2021
In the last decades, significant efforts have been devoted to developing semiconductors III-V las... more In the last decades, significant efforts have been devoted to developing semiconductors III-V lasers on silicon substrates, due to the prospects for the implementation of the high-speed lasers for optical communication systems integrated with silicon electronics and transistor logic. Low-threshold ridge-waveguide and microdisk/microring lasers based on AlGaAs heterostructures with self-organizing quantum dots In(Ga)As grown on Si substrates were demonstrated [1] , [2] . However, lasers synthesized on silicon are still inferior to analogs grown on native substrates (GaAs) [3] , due to higher defect densities caused by differences in polarity, lattice constants and coefficients thermal expansion of III-V materials and silicon. The epitaxial growth of laser heterostructures on native substrates (e.g. GaAs) and subsequent transfer of ready-made microlasers to silicon can help to avoid problems associated with monolithic integration of III-V and Si. Ring and disk microlasers have attracted more and more attention and are considered as promising sources of emission for inter-chip data transmission. The advantages of such microcavities are the high Q-factor of the whispering gallery (WG) modes, small size and, accordingly, low threshold currents and power consumption. In this work we study integration of InAs/GaAs quantum dot microdisk lasers on silicon either retaining the native substrate or separating from the substrate using a sacrificial layer.
Material gain of InGaAs/GaAs quantum well-dots
Semiconductor Science and Technology, 2020
Semiconductors, 2019
Spontaneous emission in a vertical cavity surface emitting laser (VCSEL) have been studied. It wa... more Spontaneous emission in a vertical cavity surface emitting laser (VCSEL) have been studied. It was estimated that a significant part of the spontaneous emission (~1/3) in a conventional VCSEL goes into a waveguide mode that propagates in the plane of the Bragg mirrors. The theoretical study of a recently proposed anti-waveguide VCSEL design is presented and the damping of the waveguide mode emission is shown. Moreover we calculate that 3λ/2-cavity AVCSEL has almost the same gain value for vertical mode as conventional λ-VCSEL despite the higher cavity width due to the light redistribution effect while λ/2-cavity AVCSEL has 19% higher gain.
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Papers by Mikhail Maximov