Optical Bottle Research Articles

Airyprime beam: From the non-truncated case to truncated one

The present paper investigates the spatial proprieties of a novel beam introduced recently known as Airyprime beam, its on-axis and transverse intensities are studied numerically. It is shown that the focused Airyprime beam exhibits two focuses corresponding to two intensities maxima limiting an Optical Bottle Beam (OBB), the latter is characterized by its length where numerical examples show that we can adjust and change it by changing the scale parameter w0x which is related directly to the input width of the Airyprime beam. The spatial proprieties of the truncated Airyprime beam are also studied; by acting on the aperture diameter one can modify the on-axis intensity to choose between a mono focus beam and dual focus beam. Depending on the aperture diameter the Airyprime beam is transformed into other interesting laser beam patterns such as, a flattop beam, Gaussian beam, and tune Optical Bottle Beam. The Airyprime beam could be interesting tool of trapping and guiding microparticles.

Spatial characteristics of the truncated circular Airyprime beam

The circular Airyprime (CiAiP) beam is introduced in this paper. The spatial proprieties are well discussed and compared to the first order radial Laguerre–Gaussian beam LG10. The width, the divergence and the beam propagation factor are calculated based on the second order moments method, the latter is equal to M2 = 3.08. The free propagating CiAiP beam exhibits an unexpected non-diffracting character, it doesn’t spread through propagation. The on-axis intensity of the focused circular Airyprime beam is also explored, it exhibits a dual focus corresponding to two on-axis intensity maxima, it could be modified under diffraction using a hard circular aperture. The latter presents a cheap beam shaper, it is shown that a hard aperture could transform an input circular Airyprime beam into perfect ringed beam, a perfect Gaussian beam and a top hat beam. By combining the axial and the transversal behavior of a truncated circular Airyprime beam for a particular aperture diameter a perfect cylindrical optical bottle beam is obtained. The present work could be of big interest in the field of structured light.

Observation of microscale nonparaxial optical bottle beams.

We predict and experimentally observe three-dimensional microscale nonparaxial optical bottle beams based on the generation of a caustic surface under revolution. Such bottle beams exhibit high contrast between the surrounding surface and the effectively void interior. Via caustic engineering, we can precisely control the functional form of the high-intensity surface to achieve microscale bottle beams with longitudinal and transverse dimensions of the same order of magnitude. Although, in general, the phase profile at the input plane can be computed numerically, we find closed-form expressions for bottle beams with various types of surfaces both in the real and in the Fourier space.

Periodic abruptly autofocusing and autodefocusing behavior of circular Airy beams in parabolic optical potentials

In this paper, we investigate the propagation dynamics of circular Airy beams (CAB) in a medium with radial parabolic potential both analytically and numerically. Our results show that CAB will exhibit periodic abruptly autofocusing behavior under the action of radial parabolic potentials. Within every period, we interestingly observe a novel autodefocusing behavior, which manifests that optical peak intensity abruptly decreases by several orders of magnitude. In particular, such unique “autofocusing-to-autodefocusing” effect can lead to the formation of a series of elegant periodic optical bottles having paraboloidal shapes during the whole propagation process. Our findings indicate that CAB is expected to provide a unique tool in optical micromanipulation and optical trapping.

Generation of High-Power Bottle Beams and Autofocusing Beams

We propose and experimentally demonstrate an optical bottle beam (BB) and an abruptly autofocusing beam (AB), which were generated using a ring-Airy beam array. The method can form BB arrays with varying sizes during propagation; consequently, it can produce multiple optical traps. Additionally, the BB size and the AB focal position can be controlled by varying the array radius. The intensity of the resulting beams improved significantly with increasing array number, and the value abruptly increased 800 times at the focal position when array radius and number were 2 mm and 64, respectively. It is the lateral acceleration of Airy beams that causes this abrupt increase in intensity. Numerical simulations were consistent with experimental results. These advantages could be beneficial for potential applications, such as optical traps, laser ablation, and the ignition of nonlinear effect. (The caption of Graphic Abstract is generation of high-power BBs and ABs using a ring-Airy beam array.)

Conical Refraction Bottle Beams for Entrapment of Absorbing Droplets

Conical refraction (CR) optical bottle beams for photophoretic trapping of airborne absorbing droplets are introduced and experimentally demonstrated. CR describes the circular split-up of unpolarised light propagating along an optical axis in a biaxial crystal. The diverging and converging cones lend themselves to the construction of optical bottle beams with flexible entry points. The interaction of single inkjet droplets with an open or partly open bottle beam is shown implementing high-speed video microscopy in a dual-view configuration. Perpendicular image planes are visualized on a single camera chip to characterize the integral three-dimensional movement dynamics of droplets. We demonstrate how a partly opened optical bottle transversely confines liquid objects. Furthermore we observe and analyse transverse oscillations of absorbing droplets as they hit the inner walls and simultaneously measure both transverse and axial velocity components.

Optical frequency combs generated mechanically.

An elongated bottle microresonator with nanoscale parabolic effective radius variation can possess a series of dense equally spaced optical eigenfrequencies whose separation can match the eigenfrequency of its axially symmetric acoustic mode. It is shown that this acoustic mode can parametrically excite optical modes and give rise to a highly equidistant and moderately broadband optical frequency comb with the teeth spacing independent of the input laser power and the amplitude of mechanical vibrations.

Birefringent masks that are optimal for generating bottle fields.

An optical bottle field containing a three-dimensional intensity null at the focal point can be generated by placing a spatially inhomogeneous birefringent mask at the pupil of an aplanatic high-NA focusing system. We derive the optimal birefringence distribution for which a uniformly polarized input beam is converted into a bottle field with the sharpest possible null in intensity. We show that a stress engineered optical (SEO) window, which has a radially varying retardance, followed by a half-wave plate, performs nearly as well as the optimal solution. Experimental results corroborate that an SEO element can be used to generate a bottle field.

Optical bottle versus acoustic bottle and antibottle resonators.

The theory of slow acoustic modes propagating along the optical fiber and being controlled by the nanoscale variation of the effective fiber radius (analogous to the theory of slow optical whispering gallery modes) is developed. Surprisingly, it is shown that, in addition to acoustic bottle resonators (which are similar to optical bottle resonators), there exist antibottle resonators, the neck-shaped deformations of the fiber that can fully confine acoustic modes. It is also shown that an eigenfrequency of the mechanical vibrations of a silica parabolic bottle resonator can match the separation between the eigenfrequencies of a series of its optical modes, thereby enabling the resonant mechanical excitation of these series. The developed theory paves the groundwork for slow-mode optomechanics in an optical fiber.

Dual Abruptly Focus of Modulated Circular Airy Beams

In this paper, we propose a new kind of circular Airy beam whose spectrum is imposed an initial quadratic phase modulation (QPM). Unlike common abruptly autofocusing beams, we find that such modulated circular Airy beams (MCAB) at image plane, i.e., initial plane, may be morphed into conventional Airy patterns or Bessel-like patterns in spatial regime, depending on the magnitude of QPM. We further investigate the propagation characteristics of the MCAB both analytically and numerically. It is found that the focal intensity, as well as the size of focal spot, do not change with the QPM, but the latter greatly affects the focal trajectory and the focal position of MCAB. In particular, we show that, for the case of Airy pattern, MCAB will exhibit a dual abruptly focusing behaviors having the same focal intensity as well as size of focal spot, where there is one focus behind the image plane, and the another one is in front of it. On the other hand, for the case of Bessel-like pattern, the dual abruptly foci are simultaneously observed behind the image plane for positive QPM but in front of it for negative QPM, thus leading to the formation of an elegant optical bottle with paraboloidal shape. Such novel dual focusing behaviors are expected to be applied in the field of optical trapping and particle acceleration.

Bottle microresonator broadband and low-repetition-rate frequency comb generator.

We propose a new type of broadband and low repetition rate (RR) frequency comb generator that has the shape of an elongated and nanoscale-shallow optical bottle microresonator created at the surface of an optical fiber. The free spectral range (FSR) of the broadband azimuthal eigenfrequency series of this resonator is the exact multiple of the FSR of the dense and narrowband axial series. The effective radius variation of the microresonator is close to a parabola with a nanoscale height that is greater or equal to λ/2πn0. (Here λ is the characteristic radiation wavelength and n0 is the refractive index of the microresonator material.) Overall, the microresonator possesses a broadband, small FSR and accurately equidistant spectrum convenient for the generation of a broadband and low RR optical frequency comb. It is shown that this comb can be generated by pumping with a cw laser, with a radiation frequency that matches a single axial eigenfrequency of the microresonator or, alternatively, by pumping with a mode-locked laser, which generates a narrowband low RR comb matching a series of equidistant axial eigenfrequencies situated between adjacent azimuthal eigenfrequencies.

Conical refraction: fundamentals and applications

AbstractIn 1832 Hamilton predicted that a collimated light beam propagating through a biaxial crystal parallel to one of its optical axes refracts as a slanted cone within the crystal and emerges as a hollow light cylinder, this optical effect being named as conical refraction (CR). The diffractive solution of CR presented by Belsky and Khapalyuk in 1978 and the corresponding re‐formulation carried out by Berry in 2004 rekindled this old and almost forgotten phenomenon. In this article, we review the CR phenomenon following different approaches that allow understanding light propagation in biaxial crystals, including the case of multiple crystals in cascade. We then focus on the description of the singular properties of the CR beams, presenting some examples such as optical bottle beams and beams carrying orbital angular momentum. All these features are used to introduce some of the most appealing applications of CR in the fields of optical trapping, free‐space optical communications, polarization metrology, super‐resolution imaging, two‐photon polymerization, and lasers. image

Controllable light capsules employing modified Bessel-Gauss beams.

We report, in theory and experiment, on a novel class of controlled light capsules with nearly perfect darkness, directly employing intrinsic properties of modified Bessel-Gauss beams. These beams are able to naturally create three-dimensional bottle-shaped region during propagation as long as the parameters are properly chosen. Remarkably, the optical bottle can be controlled to demonstrate various geometries through tuning the beam parameters, thereby leading to an adjustable light capsule. We provide a detailed insight into the theoretical origin and characteristics of the light capsule derived from modified Bessel-Gauss beams. Moreover, a binary digital micromirror device (DMD) based scheme is first employed to shape the bottle beams by precise amplitude and phase manipulation. Further, we demonstrate their ability for optical trapping of core-shell magnetic microparticles, which play a particular role in biomedical research, with holographic optical tweezers. Therefore, our observations provide a new route for generating and controlling bottle beams and will widen the potentials for micromanipulation of absorbing particles, aerosols or even individual atoms.

Permanent matching of coupled optical bottle resonators with better than 0.16 GHz precision.

The fabrication precision is one of the most critical challenges to the creation of practical photonic circuits composed of coupled high Q-factor microresonators. While very accurate transient tuning of microresonators based on local heating has been reported, the record precision of permanent resonance positioning achieved by post-processing is still within 1 and 5 GHz. Here we demonstrate two coupled bottle microresonators fabricated at the fiber surface with resonances that are matched with a better than 0.16 GHz precision. This corresponds to a better than 0.17 Å precision in the effective fiber radius variation. The achieved fabrication precision is only limited by the resolution of our optical spectrum analyzer and can be potentially improved by an order of magnitude.

Transformation of a LG10 beam into an optical bottle beam

We have demonstrated that a simple diaphragm can play the role of a very cheap reconfigurable diffractive optical element allowing the generation of interesting laser beam patterns. For instance, a truncated Laguerre–Gauss LG10 beam (one peak surrounded by one ring) can be transformed in the focal plane of a lens into an optical bottle beam (OBB) which consists to a dark (or minimal intensity) region surrounded by higher intensity light in the three principal directions. Depending on the beam truncation, one can also observe a flat-top intensity profile.

Light capsules shaped by curvilinear meta-surfaces

We propose a simple yet efficient method for generating in-plane hollow beams with a nearly-full circular light shell without the contribution of backward propagating waves. The method relies on modulating the phase in the near field of a centro-symmetric optical wavefront, such as that from a high-numericalaperture focused wave field. We illustrate how beam acceleration may be carried out by using an ultranarrow non-flat meta-surface formed by engineered plasmonic nanoslits. A mirrorsymmetric, with respect to the optical axis, circular caustic surface is numerically demonstrated that can be used as an optical bottle.

Three-dimensional laser trapping on the base of binary radial diffractive optical element

A radially symmetric binary diffractive optical element to generate an optical bottle beam is designed, fabricated, and characterized. Analysis of the numerical simulation and experimental research results shows that the fabricated element is well suited for solving three-dimensional (3D) laser trapping problems.

自弯曲艾里光束阵列产生的可调局域空心光束

自弯曲艾里光束阵列产生的可调局域空心光束

Comparison between interferometric and diffractive laser beam shaping

We consider the transformation of a Gaussian laser beam into a flat-top intensity profile or into an optical bottle beam (OBB) by resorting to a diffractive or an interferometric method. The diffractive technique is based on the use of a diffractive optical element consisting in a π-plate, while the interferometric technique uses a Michelson interferometer (MI). The coaxial superposition of two coherent Gaussian beams yields to a flat-top or a OBB in the focal plane of a lens depending on the geometric characteristics of the MI. The performances of the two techniques are compared.

Surface charge effects on optical trapping of nanometer-sized lipid vesicles.

Optical trapping of nanometer-sized lipid vesicles has been challenging due to the low refractive index contrast of the thin lipid bilayer to the aqueous medium. Using an "optical bottle", a recently developed technique to measure interactions of nanoparticles trapped by an infrared laser, we report, for the first time, quantitative measurements of the trapping energy of charged lipid vesicles. We found that the trapping energy increases with the relative amount of anionic lipids (DOPG) to neutral lipids (DOPC) in vesicles. Moreover, as monovalent salt is added into the exterior solution of vesicles, the trapping energy rapidly approaches zero, and this decrease in trapping energy strongly depends on the amount of anionic lipids in vesicles. A simple model with our experimental observations explains that the trapping energy of charged lipid vesicles is highly correlated with the surface charge density and electric double layer. In addition, we demonstrated selective trapping of a binary mixture of vesicles in different mole fractions of charged lipids, a strategy that has potential implications on charge selective vesicle sorting for engineering applications.