Fabry-Perot Lasing Research Articles

Gain Coefficient Comparison between Silicon and InP Laser Diode Substrate

The article presents the study on the comparison of gain coefficient of laser diode on silicon and InP substrate. Fabry–Perot GaInAsP bulk laser diode on InP/Si substrate is successfully obtained to study the optical gain coefficient of laser diode. The influences of temperature, threshold current comparison, and optical gain achievements between bulk InP/Si laser diode substrate and InP laser diode substrate are also analyzed using the same growth structure. A new approach is found by the research group which involves bonding of 1 μm InP semiconductor crystal and a low‐cost silicon crystal prior to epitaxial laser structure growth. With the help of metal–organic vapor‐phase epitaxy technique, GaInAsP double‐heterostructure laser is epitaxially deposited on the well‐bonded InP/Si crystal. Fabry–Perot lasing under pulsed condition is achieved, and the lasing characteristics of InP/Si substrate are compared with that of InP laser device to study the gain coefficient.

Dye-Derived Red-Emitting Carbon Dots for Lasing and Solid-State Lighting.

Carbon dots are carbon-based nanoparticles renowned for their intense light-emitting capabilities covering the whole visible light range. Achieving carbon dots emitting in the red region with high efficiency is extremely relevant due to their huge potential in biological applications and in optoelectronics. Currently, photoluminescence in such an energy interval is often associated with polyheterocyclic molecular domains forming during the synthesis that, however, present low emission efficiency and issues in controlling the optical features. Here, we overcome these problems by solvothermally synthesizing carbon dots starting from Neutral Red, a common red-emitting dye, as a molecular precursor. As a result of the synthesis, such molecular fluorophore is incorporated into a carbonaceous core while retaining its original optical properties. The obtained nanoparticles are highly luminescent in the red region, with a quantum yield comparable to that of the starting dye. Most importantly, the nanoparticle carbogenic matrix protects the Neutral Red molecules from photobleaching under ultraviolet excitation while preventing aggregation-induced quenching, thus allowing solid-state emission. These advantages have been exploited to develop a fluorescence-based color conversion layer by fabricating polymer-based highly concentrated solid-state carbon dot nanocomposites. Finally, the dye-based carbon dots demonstrate both stable Fabry-Perot lasing and efficient random lasing emission in the red region.

Observation of waveguide Fabry-Perot lasing in highly efficient Si nanocrystals

A luminescent Si nanocrystal (SiNC) thin film with photoluminescence quantum yield (PLQY) > 70% was made by using hydrogen silsesquioxane (HSQ), followed by long-time high-pressure hydrogenation. A net optical gain of 524 ± 21 cm−1 was obtained by means of variable stripe length-shifting excitation spot (VSL-SES). A rectangularly shaped SiO2 Fabry-Perot (F-P) cavity with size of 1.5 μm (width) × 0.7 μm (height) × 2000 μm (length) was made on top of the SiNC thin film. The waveguide F-P device was pumped with a 400 nm femtosecond pulsed laser. A threshold behavior of the light emission intensity as a function of the pumping power was observed. Other lasing characteristics including spectral narrowing, polarization of the emission, and small emission angle were also observed beyond the threshold pumping power.

Electron-hole plasma Fabry-Perot lasing in a Ga-incorporated ZnO microbelt via Ag nanoparticle deposition.

In this work, individual ZnO via Ga-doped (ZnO:Ga) microbelts with excellent crystallinity and smooth facets can enable the realization of lateral microresonator Fabry-Perot (F-P) microlasers, and the F-P lasing action originates from excitonic state. Interestingly, introducing Ag nanoparticles (AgNPs) deposited on the microbelt can increase F-P lasing characteristics containing a lower threshold and enhanced lasing output. Especially for the large size AgNPs (the diameter d is approximately 200 nm), the lasing features also exhibit a significant redshift of each lasing peak and an observable broadening of the spectral line width with an increase of the excitation fluence. And the remarkable lasing characteristics are belonging to the electron-hole plasma (EHP) luminescence. The behavior and dynamics of the stimulated radiation in an AgNPs@ZnO:Ga microbelt are studied, suggesting the Mott-transition from the excitonic state to EHP state that is responsible for the F-P lasing. These features can be attributed to the working mechanism that the hot electrons created by the large size AgNPs through nonradiative decay can fill the conduction band of nearby ZnO:Ga, leading to a downward shift of the conduction band edge. This novel filling influence can facilitate bandgap renormalization and result in EHP emission. The results provide a comprehensive understanding of the transition between excitonic and EHP states in the stimulated emission process. More importantly, it also can provide new scheme to developing high efficiency and ultra-low threshold microlasing diodes.

Transformation of random lasing to Fabry-Perot lasing: observation of high temperature lasing from carbon dots.

Carbon dots (CDs), a subject of academic research, have attracted intense attention due to their intrinsic merits of high stability, low cost, and low toxicity. However, the absence of highly efficient red-emitting CDs restricts their application in a variety of areas including lasers. In this work, red emissive CDs (R-CDs) with a quantum yield as high as 66.7% were prepared using 1,3-dihydroxynaphthalene as the initial source. It is found that the superior optical properties of R-CDs are attributed to the high oxidation degree and high ratio of hydroxyl functional groups on the surface of CDs. Red emissive random lasing at 612 nm was realized from a microcavity by using the R-CDs/epoxy composite as the gain medium at room temperature. Simultaneously, the transformation of random lasing to Fabry-Perot lasing in the same laser cavity at 250 °C was observed. This is on account of the declining optical gain which is insufficient to support random lasing in the microcavity at high temperatures. As a result, CD based Fabry-Perot lasing was achieved at a temperature as high as 250 °C for the first time.

Employing rhodium tripod stars for ultraviolet plasmon enhanced Fabry–Perot mode lasing

Rhodium tripod stars serving as ultraviolet plasmons can provide a highly competitive platform to achieve high-performance Fabry–Perot lasing of quadrilateral ZnO microwires.

Robust Cesium Lead Halide Perovskite Microcubes for Frequency Upconversion Lasing

AbstractHalide perovskite nanomaterials have recently attracted a lot of attention in the nanoscale laser research field, especially two‐photon pumped lasing in halide perovskite nanomaterials has been considered as an ideal alternative strategy to achieve frequency upconversion. However, the poor stability of current organic–inorganic lead halide perovskite materials hinder their further practical applications. Herein, facile solution‐processed cesium lead halide perovskite CsPbX3 (X = Br, I, or Cl) microcubes with low‐threshold lasing, high quality, enhanced stability, and excellent wavelength tunability are reported. These as‐prepared CsPbX3 microcubes display excellent structure stability under ambient conditions for several months and they are found to be more robust than their organic–inorganic counterparts. The smooth end facets and wavelength‐comparable dimensions make these microcubes promising for high‐quality laser cavities in three dimensions. Fabry–Perot lasing is demonstrated in CsPbX3 microcubes, the process of which is investigated by dynamic emission. In addition, tunable amplified spontaneous emission is achieved with low threshold under both one‐ and two‐photon excitation, which can maintain a stable emission for over 10 hours under continuous intense laser shots in ambient atmosphere. The findings suggest that solution‐processed all‐inorganic perovskite microcubes can be used as excellent gain medium for frequency upconversion lasers, which would offer a new platform for nonlinear photoelectric devices.

Optical and Exciton Dynamical Properties of a Screw-Dislocation-Driven ZnO:Sn Microstructure.

Screw dislocation plays a critical role in crystal growth and significantly affects the carrier dynamics process of luminescent semiconductor materials. In this paper, we report a novel screw-dislocation-induced ZnO:Sn hillock microstructure. The detailed growth process and possible formation mechanism of screw dislocation are demonstrated. The temperature-dependent photoluminescence reveals the free exciton recombination emission mechanism of the ZnO:Sn hillock microstructure. By comparing time-resolved photoluminescence spectra with those of two other samples without screw dislocations, it is found that the screw dislocation in the ZnO:Sn microstructures effectively decreases the carrier lifetime. In addition, UV Fabry-Perot lasing action is observed from the ZnO:Sn hillock microstructure, and the numerical simulation of the standing wave pattern and light intensity distribution further confirm the Fabry-Perot lasing mechanism. Therefore, ZnO:Sn can be utilized as a UV laser gain medium, and its optical properties can be modulated by screw dislocation.

Plasmon coupled Fabry-Perot lasing enhancement in graphene/ZnO hybrid microcavity.

The response of graphene surface plasmon (SP) in the ultraviolet (UV) region and the realization of short-wavelength semiconductor lasers not only are two hot research areas of great academic and practical significance, but also are two important issues lacked of good understanding. In this work, a hybrid Fabry-Perot (F-P) microcavity, comprising of monolayer graphene covered ZnO microbelt, was constructed to investigate the fundamental physics of graphene SP and the functional extension of ZnO UV lasing. Through the coupling between graphene SP modes and conventional optical microcavity modes of ZnO, improved F-P lasing performance was realized, including the lowered lasing threshold, the improved lasing quality and the remarkably enhanced lasing intensity. The underlying mechanism of the improved lasing performance was proposed based on theoretical simulation and experimental characterization. The results are helpful to design new types of optic and photoelectronic devices based on SP coupling in graphene/semiconductor hybrid structures.

Electrical pumping Fabry–Perot lasing of a III-V layer on a highly doped silicon micro rib

Direct-current-pumped Fabry–Perot lasing was observed from a Si/III-V hybrid laser fabricated by the Ar/O2 plasma assisted direct bonding of an InP-based III-V active layer on a highly doped silicon micro rib. Electrical pumping from a silicon micro rib to InGaAsP multiple quantum wells (MQWs) for generating CW Fabry–Perot lasing was successfully demonstrated at a threshold current of 65 mA at 5 °C. The semiconductive and optical properties of the hetero-junction between the silicon micro rib and InGaAsP MQWs under direct current injection were measured and discussed.

Electrically tunable Fabry–Perot lasing in nematic liquid crystal cells

Liquid crystal lasers have great potential as small-sized, low-cost, widely tunable lasers. In this paper, we report tunable lasing based on Fabry–Perot interference in nematic liquid crystal (NLC) cells with a low quality factor. The influence of the cell thickness on the laser performance is addressed in detail. Cells with and without an aluminum mirror as a back electrode were investigated, and the experimental results were compared with theory and simulations. Applying a small voltage over the NLC cell gave rise to a reorientation of the molecules. This enabled electrical tuning of the emission wavelength over more than 9 nm. Although the lasing threshold is higher than for cholesteric liquid crystal lasers, the Fabry–Perot type liquid crystal laser offers similar slope efficiency.

Self-catalytic growth of CdS nanobelt and its Fabry–Perot lasing action

CdS nanobelts were fabricated by a vapor transport method in the absence of a catalyst. The scanning electron microscopy and transmission electron microscopy demonstrated that the CdS nanobelts had regular morphology, smooth surface and single-crystalline structure. Under the excitation of 325nm line of a femtosecond pulsed laser, the amplified spontaneous emission with the typical band narrowing process was observed. The Fabry–Perot mode lasing action in a single CdS nanobelt was observed by the confocal micro-photoluminescence technique. The result indicated that the CdS nanobelt can be used as ideal microlaser material in the future optoelectronic devices.

Use of distributed Bragg reflectors to enhance Fabry–Pérot lasing in vertically aligned ZnO nanowires

An optically pumped ZnO nanowire laser with a 10-period SiO2/SiN x distributed Bragg reflector (DBR) was demonstrated. Stimulated emissions with equally distributed Fabry–Perot lasing modes were observed at pumping powers larger than 121 kW/cm2. This result, when compared to nanowires of the same length and without a DBR structure, shows that a lower threshold of pumping power, higher quality factor, and larger cavity finesse can be achieved due to the high reflectivity of the DBR in the designed wavelength range. A coexistence of stimulated and spontaneous emissions was also observed above threshold and was attributed to partially confined waveguide modes in nanowires with diameters smaller than 100 nm.

Inverse scattering approach to multiwavelength Fabry-Pérot laser design

A class of multiwavelength Fabry-Perot lasers is introduced where the spectrum is tailored through a non-periodic patterning of the cavity effective index. The cavity geometry is obtained using an inverse scattering approach and can be designed such that the spacing of discrete Fabry-Perot lasing modes is limited only by the bandwidth of the inverted gain medium. A specific two-color semiconductor laser with a mode spacing in the THz regime is designed, and measurements are presented demonstrating the simultaneous oscillation of the two wavelengths. The extension of the Fabry-Perot laser concept described presents significant new possibilities in laser cavity design.