Surface Plasmon Amplification By Stimulated Emission Of Radiation Research Articles

SPASER as Nanoprobe for Biological Applications: Current State and Opportunities

AbstractSince the concept of surface plasmon amplification by stimulated emission of radiation (SPASER) was proposed in 2003, great progresses have been made on two kinds of plasmonic nanolasers, namely SPASER device and SPASER nanoparticle. In comparison, SPASER nanoparticle, with ultra‐narrow emission line, small size, and good biocompatibility, is a kind of promising luminescent nanoprobe and has a bright application prospect in biomedical imaging and sensing. Hence, it is gradually becoming an attractive research hotspot in the world. However, as the research on SPASER nanoparticle is still in its infancy, there are still lots of problems to be solved before it is widely applied. In this paper, the latest research advances of SPASER nanoparticles and their biological applications are reviewed. Besides existing problems, challenges and opportunities of SPASER nanoparticles as next generation luminescent nanoprobes are discussed as well.

Developing a time-domain method for simulating statistical behavior of many-emitter systems in the presence of electromagnetic field.

In this paper, one of the major shortcomings of the conventional numerical approaches is alleviated by introducing the probabilistic nature of molecular transitions into the framework of classical computational electrodynamics. The main aim is to develop a numerical method which is capable of capturing the statistical attributes caused by the interactions between a group of spontaneous as well as stimulated emitters and the surrounding electromagnetic field. The electromagnetic field is governed by classical Maxwell's equations, while energy is absorbed from and emitted to the (surrounding) field according to the transitions occurring for the emitters, which are governed by time-dependent probability functions. These probabilities are principally consistent with quantum mechanics. In order to validate the proposed method, it is applied to three different test cases: directionality of fluorescent emission in a corrugated single-hole gold nanodisk, spatial and temporal coherence of fluorescent emission in a hybrid photonic-plasmonic crystal, and stimulated emission of a core-shell SPASER (surface plasmon amplification by stimulated emission of radiation). The results are shown to be closely comparable to the experimental results reported in the literature.

A multi-wavelength SPASER based on plasmonic tetramer cavity

Surface plasmon (SP) amplification by stimulated emission of radiation (SPASER) as nanoscale coherent light source has great applications in biomedical sensing, imaging, optical communications, and ultrafast spectroscopy. Shrinking coherent light sources to subwavelength regions can provide new insight into light-matter interactions. In this theoretical work, we utilize a multi-resonance plasmonic substrate as a cavity to design a multi-wavelength SPASER. The plasmonic substrate consists of four crisscrossed sub-elements with symmetric disposition, the tetramer can support multiple plasmonic resonance modes. With the appropriate gain layer, the different SPs modes can be stimulated, and SPASER with different wavelengths can be obtained.

Tunable spherical graphene surface plasmon amplification by stimulated emission of radiation

A structure is suggested for spasing. The presented surface plasmon amplification by stimulated emission of Radiation (SPASER) is made up of a graphene nanosphere, which supports localized surface plasmon modes, and a quantum dot array, acting as a gain medium. The gain medium is pumped by an external light source. Since all the plasmons are carried on a graphene platform, the structure features coherent surface plasmons with high confinement and large life time. All the structures are analyzed theoretically using full quantum mechanical description. The main advantage of the proposed SPASER is its simple tuning capability of changing graphene’s Fermi level, which is performed by either chemical doping in the manufacturing time or electrostatic gating. We suggest the utilization of the proposed SPASER for exciting coherent long-range surface plasmons on a graphene sheet. The near field of the SPASER couples to the surface plasmons on graphene sheet and compensates the large momentum mismatch between surface plasmons and photons.

Free electrons excited SPASER.

Surface plasmon amplification by stimulated emission of radiation (SPASER) is discovered and used for realizing lasers at nanometer scale. The conventional gain media that are applied in SPASER are solid materials, such as organic dye or semiconductor, which limits the frequency range of SPASER. The free electrons could be considered as a kind of gain medium for emitting radiation. Here, we investigate theoretically the SPASER, which is excited by free electrons. We also demonstrate the tunable, deep-ultraviolet, and ultracompact laser numerically by having free electrons interact with surface plasmon polariton mode supported on metal surface. The output power density could reach about 30 W/μm2 and the wavelength in deep ultraviolet could be widely tuned by varying the electron energy. This work offers a way of realizing integrated free electron laser in the ultraviolet frequency region.

Efficient surface plasmon amplification in gain-assisted silver nanotubes and associated dimers

SPASER (surface plasmon amplification by stimulated emission of radiation) properties in active SiO2–Ag nanotubes and associated dimers have been investigated by using the scattering theory and the finite element method. In the active Ag nanotube, as the gain coefficient of the core increases to a critical value, a super-resonance occurs. The SPASER phenomenon also can be found in the active Ag nanotube dimer. The strong couplings between two nanotubes lead to larger gain threshold for the active Ag nanotube dimer compared with the active Ag nanotube. At the super-resonance, the maximal surface enhanced Raman scattering factor at the “hot spot” in the active Ag nanotube dimer can achieve about 8 × 1018, which is large enough for single molecule detection. Furthermore, with increasing the separation between two Ag nanotubes, the gain threshold value for the super-resonance of the active Ag nanotube dimer decreases, while the corresponding super-resonance wavelength increases first and then decreases.

Room temperature plasmonic lasing in a continuous wave operation mode from an InGaN/GaN single nanorod with a low threshold.

It is crucial to fabricate nano photonic devices such as nanolasers in order to meet the requirements for the integration of photonic and electronic circuits on the nanometre scale. The great difficulty is to break down a bottleneck as a result of the diffraction limit of light. Nanolasers on a subwavelength scale could potentially be fabricated based on the principle of surface plasmon amplification by stimulated emission of radiation (SPASER). However, a number of technological challenges will have to be overcome in order to achieve a SPASER with a low threshold, allowing for a continuous wave (cw) operation at room temperature. We report a nano-SPASER with a record low threshold at room temperature, optically pumped by using a cw diode laser. Our nano-SPASER consists of a single InGaN/GaN nanorod on a thin SiO2 spacer layer on a silver film. The nanorod containing InGaN/GaN multi-quantum-wells is fabricated by means of a cost-effective post-growth fabrication approach. The geometry of the nanorod/dielectric spacer/plasmonic metal composite allows us to have accurate control of the surface plasmon coupling, offering an opportunity to determine the optimal thickness of the dielectric spacer. This approach will open up a route for further fabrication of electrically injected plasmonic lasers.

Dye-doped polystyrene-coated gold nanorods: towards wavelength tuneable SPASER

We present the synthesis and photophysical study of a new type of fluorescent gold core–polystyrene shell nanoparticles fabricated by emulsion polymerization at neutral pH. The thickness of the PS shell can be controlled by varying the synthesis conditions. Decrease in the fluorescence intensity and lifetime of Rhodamine 800 (Rh800) were observed, indicating energy transfer from Rh800 to gold nanorods. This study suggests the possibility of exploiting dye-doped polystyrene shells as a gain medium to compensate for the energy loss of longitudinal surface plasmon resonance of gold nanorods and paving the way for eventually realizing a SPASER (surface plasmon amplification by stimulated emission of radiation) optical source of tuneable wavelength.