Random Laser Research Articles

Observation and all-optical manipulation of replica symmetry breaking dynamics in a multi-Stokes-involved Brillouin random fiber laser photonic system

In this paper, we propose and demonstrate an all-optical control of RSB transition in a multi-wavelength Brillouin random fiber laser (MWBRFL). Multi-order Stokes light components can be subsequently generated by increasing the power of the Erbium-doped fiber amplifier (EDFA) inside the MWBRFL, providing additional disorder as well as multiple Stokes-involved interplay. It essentially allows diversified laser mode landscapes with adjustable average mode lifetime and random mode density of the 1st order Stokes, which benefits the switching between replica symmetry breaking (RSB) and replica symmetry (RS) states in an optically controlled manner. Results show that the average mode lifetime of the 1st order Stokes component gradually decreases from 250.0 ms to 1.2 ms as high orders from the 2nd to the 5th of Stokes components are activated. Meanwhile, the order parameter q of the 1st order Stokes random lasing emission presents distinct statistical distributions within the selective sub-window under various EDFA optical powers. Consequently, all-optical dynamical control of the 1st Stokes random laser mode landscapes with adjustable average mode lifetime turns out to be attainable, facilitating the RSB transition under an appropriate observation time window. These findings open a new avenue for exploring the underlying physical mechanisms behind the occurrence of the RSB phenomenon in photonic complex systems.

Broad-band-enhanced plasmonic random laser in silver nanostar arrays

As a novel optical device, the plasmonic random laser has unique working principle and emission characteristics. However, the simultaneous enhancement of absorption and emission by plasmons is still a problem. In this paper, we propose a broad-band-enhanced plasmonic random laser. Two-dimensional silver (Ag) nanostar arrays were prepared using a bottom-up method with the assistance of self-assembled nanosphere templates. The plasmon resonance of Ag nanostars contributes to the pump light absorption and photoluminescence (PL) of RhB. Coherent random lasing was achieved in RhB@PVA film based on localized surface plasmon resonance (SPR) dual enhancement and scattering feedback of Ag nanostars. Ag nanostars prepared with different nanosphere diameters affect the laser emission wavelength. In addition, the random laser device achieves wavelength tunability on a flexible substrate under mechanical external force.

Arbitrary topological charge vortex beams from carbon dots random lasers

Arbitrary topological charge vortex beams from carbon dots random lasers

Crystallization-Driven Tuneable Lasing of Perylene Doped into the Nematic Liquid Crystal

Versatile devices with tunable capabilities for controlling lasing wavelength and intensity are in high demand. Liquid crystals (LCs) exhibit immense potential for such applications, offering fine-tuning possibilities through external factors. On the other hand, laser technology is currently a research hotspot in optoelectronics, and also in practical applications. The recent market introduction of laser television marks a significant stride toward making such advanced technology accessible in every household. In synergy with laser pumping, the LCs unquestionably can be rediscovered. This study presents a comprehensive investigation into the crystallization phenomenon within a host-guest device, compact in size, free from moving parts, and integrating the liquid crystalline (LC) matrix doped with 3,4,9,10-tetra-(3-alcoxy-carbonyl)-perylene (THCP) dye. The focus lies in examining the influence of varying dye concentrations on multicolor fluorescence, lasing behavior, and device morphology. The systematic analysis of Random Lasing (RL) energy thresholds and the impact of DC voltage on light intensity modulation is demonstrated. Morphological changes were monitored in real-time using optical microscopy techniques, including crossed polarizer, and fluorescence imaging under 450 nm excitation. Utilizing advanced Transmission Electron Microscopy (TEM) techniques, we explore exceptional insights into our set of devices, providing novel information about the THCP crystallization process for the first time in the literature. To gain a comprehensive understanding of the crystal forming and molecular geometry we examined additionally the THCP dye, using X-ray diffraction and Raman spectroscopy. Furthermore, we showcase that varying the pumping energy enables multicolor tuning in the fabricated systems, presenting an attractive feature in the context of laser display technologies.

Time sequence variation of incoherent and coherent random laser based on positive replica of abalone shell

Time sequence variation of incoherent and coherent random laser based on positive replica of abalone shell

Employment of nonlinear optical properties of GO/Ag nanocomposite scatterer materials for achieving random lasing in the visible region in the gain medium of a commercially available dye

Graphene oxide (GO) and silver nanoparticles (AgNPs) are recently been widely employed in various sectors including in photonics applications due to their fascinating properties. On the other hand, huge interests are shown by the researchers for development of scatterer materials for achieving random laser (RL) with improved performances. In this work, the GO/Ag nanocomposite material comprising of GO nanosheets and AgNPs have been prepared and its remarkable nonlinear optical (NLO) properties are employed for the first time to demonstrate RL in the visible region by the introduction of disorder and multiple scattering within the amplifying medium of Rhodamine-B dye. Interestingly by changing the cuvette path lengths, here we have shown that the gain volume within the amplifying media can be varied effectively, which directly influence the lasing threshold. The larger value of NLO coefficients in GO/Ag scatterer induced greater refractive index contrast (Δn) between the scatterer and surrounding medium and thus enhances the light-matter interactions in the GO/Ag nanocomposite and consequently the lasing threshold for RL generation is reduced significantly by 50 % than that of bare GO as scattering center. This report opens an exciting prospect of using NLO properties of GO/Ag nanocomposite for achieving enhanced scattering in different gain media for demonstration of low threshold RL, which may revolutionize the future development of RLs.

Spectral Manipulations of Random Fiber Lasers: Principles, Characteristics, and Applications

Spectral Manipulations of Random Fiber Lasers: Principles, Characteristics, and Applications

Wavelength-interval Switchable Brillouin-Raman Random Fiber Laser through Brillouin pump manipulation

Abstract A wavelength-interval switchable Brillouin-Raman random fiber laser (BRRFL) based on Brillouin pump (BP) manipulation is proposed in this letter. The proposed wavelength-interval switchable BRRFL has a full-open cavity configuration, featuring multiwavelength output with wavelength interval of double Brillouin frequency shifts. Through simultaneously injecting the BP light and its first-order stimulated Brillouin-scattered light into the cavity, the laser output exhibits a wavelength interval of single Brillouin frequency shift. The wavelength-interval switching effect can be manipulated by controlling the power of the first-order stimulated Brillouin scattering light. The experimental results show the multiwavelength output can be switched between double Brillouin frequency shift multiwavelength emission with a broad bandwidth of approximately 60 nm and single Brillouin frequency shift multiwavelength emission of 44 nm. The flexible optically controlled random fiber laser with switchable wavelength interval makes it useful for a wide range of applications and holds significant potential in the field of wavelength-division multiplexing optical communication.

Lasing emission from ZnO hierarchical spherical microcavity

We investigated lasing characteristics of ZnO hierarchical micro-spherical particles with diameters of 1–5 μm . The lasing emission consists of a small number of discrete laser peaks unlike conventional random lasing from ZnO nanopowder-assembly. Theoretical calculations based on a many-body theory reveal that the optical gain is achieved at the observed lowest lasing threshold value, 4 mJ⋅cm−2⋅pulse−1 , which corresponds to the excited carrier density ∼2.4×1025 m−3 . Because the carrier density is much higher than the Mott density, the gain origin for lasing is electron-hole plasma recombination. The lasing frequency mode shift ( ∼1.2 meV ) is due to the refractive index change induced by exciting high carrier density up to 6.1×1025 m−3 . By changing hierarchical structures via controlling growth condition and performing the annealing treatment and performing the calculation of scattering efficiency of ZnO particles, we found that the hierarchy of the micro-spherical particle plays a crucial role of the lasing feedback: the strong light scattering at the interface between outer nanoparticles with the sizes of 100–200 nm and smaller ones with the sizes of 10–60 nm consisting in the micro-spherical particle results in a light confinement. Furthermore, it has been confirmed that each discrete lasing mode shows strong gain competition with each other probably due to spatial overlap between the modes. These results suggest that both random scattering and microcavity modes contribute to the lasing oscillation.

Robust multiple focusing through scattering media via feedback wavefront shaping

The control of multiply-scattered light has greatly boosted the understanding of optics in complex photonic systems, leading to many applications including imaging, information processing, random lasing, to name just a few. Here, we demonstrate a real-time feedback approach to realize multiple focusing of multiply-scattered light, which is more robust to the inherent background field compared to the time reversal approach. Our method retrieves the optimized wavefront by aligning the high-dimensional vector of the measured pattern with that of the target pattern. Our theoretical simulations and experimental results show that the feedback approach is capable of constructing homogeneous diffraction-limited spots at predefined positions. Moreover, the peak-to-background ratio exhibits a sub-1/m decay with m being the number of focuses, indicating the excellent capability of the proposed approach to focus scattered light at multiple positions. This efficient approach provides a promising avenue toward complex control on scattered light in complex photonic media, and therefore would be useful in relevant applications such as optical imaging and optical manipulation.

High-order tunable multi-wavelength random Raman fiber laser based on few-mode fiber filter

In recent years, multi-wavelength fiber lasers have become one of the research hotspots and have been extensively applied in optical fiber communication systems. However, the presented multi-wavelength fiber lasers mainly operate in the 1.5 μm band. In this paper, a few-mode fiber filter-based cascaded high-order tunable multi-wavelength random Raman fiber laser (MWRRFL) is demonstrated, for the first time, in which a tuning range covers the 1.1–1.5 μm band. In the half-open MWRRFL, a few-mode fiber-based intermodal interferometer filter is inserted in the point reflector as a wavelength selector. The synergetic effect including high Raman gain and Rayleigh backscattering intensity in the hybrid of dispersion-shifted fiber and standard single-mode fiber is employed. It presents the capability for flat multi-wavelength random lasing stimulation. As a result, the wavelength channel number of the 6th-order random lasing is 6, with a maximum power variation of 4.66 dB and good temporal stability. The proposed cascaded tunable MWRRFL could provide a versatile source for optical fiber communication, optical fiber sensing, spectrum analysis, etc.

Bioinspired photonic crystal structures from Papilio Ulysses butterfly wings for versatile laser applications

Photonic crystals found within the wing of a Papilio Ulysses butterfly have demonstrated their efficacy in facilitating laser processes, particularly as a scattering material for imaging and illumination applications. This study delves into the investigation of the photonic crystal's band gap within the butterfly's wing, aiming to realize blue band-edge lasing using a newly developed gain medium comprising diphenylaminofluorene-based chromophores featuring a donor-acceptor-donor (D-A-D) motif. The versatility of the fabricated sample is highlighted, as it can function as both a single-mode laser and a random laser, with the operational mode determined by adjusting the excitation power and the direction of the pump source. Specifically, it exhibits a threshold of 2.5 μJ for random laser operation and 7.6 μJ for single-mode laser operation. The unique architectural elements found in the butterfly's wing, including the ridges on the wing scale and the photonic crystal within the scales, play distinct roles in enabling random laser and single-mode laser actions, respectively. This distinctive butterfly wing architecture holds promise for inspiring the development of future photoelectronic circuits requiring a hybrid design that incorporates both single-mode and comb-mode laser functionalities.

A half-open cavity random fiber laser based on a single-mode fiber and fiber Bragg grating

A random erbium-doped fiber laser based on fiber Bragg grating (FBG) and single-mode fiber (SMF) was designed and realized experimentally in this study. For the proposed random fiber laser (RFL), the 10 km long SMF was used to generate Rayleigh scattering (RS) emissions, along with FBG to provide randomly distributed feedback in the cavity. In the experiment, the RFL laser threshold is 55 mW, as the pump power is increasingly improved to 175 mW. The RS effect is gradually apparent, and 1531.59nm laser beam was formed. The signal-to-noise ratio was 38.4 dB. The FBG was stretched for sensing applications, and the lasing wavelength was adjusted from 1531.59 to 1533.83 nm when the grating was stretched from 0 to 2000 μϵ.

Self-injection locked low-noise Brillouin random fiber laser via dynamic fiber grating for QAM coherent communication

A low-noise Brillouin random fiber laser (BRFL) based on dynamic fiber grating (DFG)-assisted self-injection locking (SIL) as a laser carrier for coherent communication is proposed and experimentally demonstrated. The utilization of the DFG-based SIL basically guarantees an innovative purification of ultra-narrow-linewidth laser radiation after the removal of residual random modes from the gain competition, enabling unprecedented long-term frequency-stabilized coherent lasing resonance over a record of 30 s. Consequently, the relative intensity noise of the generated Stokes random laser is significantly suppressed by ∼20 dB, and the frequency/phase noise imposed by random mode hopping is additionally mitigated. Meanwhile, stimulated Brillouin scattering and randomly distributed Rayleigh scattering along the kilometer-long single-mode fiber further suppress laser frequency/phase noise, benefiting the ultra-narrow laser linewidth of 450 Hz. As a proof-of-concept, an 8-Gbaud (32 Gb/s) 16-quadrature amplitude modulation transmission based on the proposed self-injection locked low-noise BRFL as the laser carrier is demonstrated, achieving a low bit error rate of 3.02×10−5. The impact of the laser noise on coherent communication is systematically investigated, highlighting the potential in high-capacity coherent communication.

Direct generation of a 635 nm red random laser based on praseodymium (Pr)-doped ZBLAN fiber.

Visible random fiber lasers have garnered significant attention due to their unique emission properties and potential applications in various fields. We first, to the best of our knowledge, demonstrateda compact all-fiber structure, red wavelength, and random fiber laser (RFL) based on a double-clad Pr-doped ZBLAN fiber. The simple half-open cavity consists of a high-reflectivity fiber pigtail mirror and the Pr-doped ZBLAN fiber. The Pr-doped ZBLAN fiber not only served as a gain medium but also offered random backward scattering. We investigated the effects of different lengths on output power and slope efficiency of the RFL. For 21 m Pr-doped fiber, the RFL emitted a maximum output power of 208.50 mW with a slope efficiency of 11.09%. For 15 m Pr-doped fiber, the maximum power decreased to 120.18 mW with the slope efficiency of 7.27%. We are also numerically simulating the output power versus the pump power at different fiber lengths based on power steady-state light propagation equations. This novel RFL has the potential for broad applications in fields such as display technology, spectroscopy, biomedical imaging, and optical sensing due to its unique properties and simple all-fiber structure.

Engineering of Solid-State Nanoporous Laser through Dendrimer-Encapsulated Fluorophores.

Dendrimers─nanosized macromolecules that can function as hosts for encapsulation of guest molecules─provide new avenues to engineer gain media for lasing systems. In this context, this study investigates the interplay between the geometric features of a model porous scattering medium, nanoporous anodic alumina (NAA), and the chemical features of a model fluorophore-dendrimer encapsulation system to maximize random lasing. The inner surface of the NAA platforms is functionalized with fluorophore molecules encapsulated within dendrimers via an electrostatic interaction. The resulting solid-state composite structures emit well-resolved, intense random lasing when subjected to optical pumping. By engineering fluorophore-dendrimer and geometric features of scattering medium, we can precisely tune the characteristics of random lasing emissions. It is found that lasing structures with low porosity and thickness functionalized with fluorophore molecules encapsulated in second-generation dendrimers provide the best platforms for lasing generation, resulting in a strongly polarized laser at ∼594 nm that has a high quality-gain product of ∼1588 au, a polarization quality of ∼0.86, and a lasing threshold of ∼0.05 mJ pulse-1. Comparative analysis indicates that dendrimers achieve 2.5 times better random lasing than conventional surfactants due to improved encapsulation and minimization of photobleaching. Our results reveal the importance of the fluorophore encapsulation method and design of scattering media in the engineering of random lasing platforms for applications in optical and optoelectrical systems.

Enhancing frequency stability and mode control in a Brillouin random fiber laser with a strongly scattering disordered grating

Random fiber lasers (RFLs) with disordered scattering feedback media provide a range of functionalities and properties. The primary drawback with weak Rayleigh scattering (RS)-based RFLs is their large frequency drift and mode hopping, which are caused by the random walk of photons at different round trips. Here, we present a technique to control the mode propagation of RFLs by using a narrow gain bandwidth from stimulated Brillouin scattering and photon localization from a strongly scattering disordered grating. Multiple scattering of light within the disordered grating leads to photon localization and narrow reflection peaks, which suppresses frequency drift and reduces the number of modes. The compact Brillouin random fiber laser (BRFL) with a 200 m strongly scattering disordered grating enables single-mode lasing with an ultra-narrow linewidth of ∼650 Hz. The results of the real-time spectral evolution obtained by the heterodyne method demonstrate long-term stability of the lasing frequency, confirming the capability of the strongly scattering disordered grating to control mode propagation of the BRFL. The BRFL exhibits an ultra-high frequency stability of 0.48 MHz and mode-hop-free operation up to 120 s. This work provides a perspective on the development of RFLs with high coherence and stability.

Time-delay fourier transform spectrometer for high-speed spectral measurement

In the field of optics, there exist numerous chaotic processes like dissipative soliton dynamics, random laser generation, and laser scattering. It's very challenging to accurately capture the dynamics of these stochastic processes from the wavelength perspective with traditional spectrometers due to their slow signal integration speeds. Here, we propose a new approach, named time-delay Fourier transform spectrometer (TDFTS), to characterize the spectra of laser pulses with durations ranging from fs to ns with high speeds. Based on a fiber array with different lengths to impose frequency-dependent time delay, TDFTS efficiently maps the spectral distribution of light pulses to the temporal domain, and the spectrum can thus be detected with a photodiode and an oscilloscope. In experimental operation, the TDFTS provides spectral acquisition speeds up to 56 MHz frame rates and a bandwidth of tens of nanometers, while keeping comparable fidelity to traditional grating-scan spectrometers. While its spectral resolution of the current configuration is ∼0.1 nm, it can be further improved to 0.001 nm through optimizing the system. Based on its high speed, high spectral resolution, broad-bandwidth coverage, and compact configuration, TDFTS can be used to monitor nanosecond-scale spectral dynamics of non-repetitive optical processes.

Ultra-Broadband Visible Random Laser Generation via Hybrid SHG and SFG Processes

Ultra-Broadband Visible Random Laser Generation via Hybrid SHG and SFG Processes

Exploring Disordered Light Transport in Scattering Media to Optimize Random Lasers

Exploring Disordered Light Transport in Scattering Media to Optimize Random Lasers