Modern Optics Research Articles

11th International Symposium on Modern Optics and Its Applications (ISMOA)

PREFACEThe (11th) International Symposium on Modern Optics and Its Applications (ISMOA) is a bi-annual meeting held by the Indonesian Optical Society (InOS)/Himpunan Optika Indonesia (HOI). For 11 times, this symposium has been marked as the largest conference of the kind in Indonesia which not only gather modern optical scientists from all around Indonesia, but also from other regions around the world. ISMOA was initiated by two of the founders of The Indonesian Optical Society (InOS), Prof. Tjia and Dr. Alexander Iskandar in 2001 under the support of KNAW, The Royal Netherland Academy of Arts and Sciences and several colleagues from University of Twente. As time goes by, after the founding of InOS in 2011, ISMOA was co-organized by InOS in collaboration with ITB. For the first time, ISMOA is co-organized by InOS with another group not from ITB, of course still with strong support by InOS members from ITB.This time, the event was held at the IPB Baranang Siang Campus (Tutorial Session) and IPB International Convention Center (Symposium) in Bogor City West Java Indonesia from the 7th-10th August 2017. The value of this event is to enable scientific communication and interactions among regional scientists and distinguished scientists working in the rapidly growing field of modern optics and novel functional optical materials as well as the associated applications to information and communication technology (ICT), bio-medical sensing, imaging and biophotonics as well as applications to the development of sustainable green energy generation. This event is also designed to offer the opportunity of making direct contacts for the young Indonesian and ASEAN scientists and students with leading researchers abroad, thereby inspiring their research interest and fostering the existing research collaborations as well as extending international research networking for the future.

Extended discussion of “Metamaterial composed of different cells exhibiting a negative refraction property over multiple frequency bands”

Herein, an extended discussion of the paper published in Journal of Modern Optics, whose title is “Metamaterial composed of different cells exhibiting a negative refraction property over multiple frequency bands”, is performed. In order to realize the multiple negative passbands, different cells are chosen to stack in the x and y axes to form a two-layer or a three-layer metamaterial unit. Different multiple passbands are obtained by comparing with these units coupling cells in different directions.

Geometric metasurface enabling polarization independent beam splitting

A polarization independent holographic beam splitter that generates equal-intensity beams based on geometric metasurface is demonstrated. Although conventional geometric metasurfaces have the advantages of working over a broad frequency range and having intuitive design principles, geometric metasurfaces have the limitation that they only work for circular polarization. In this work, Fourier holography is used to overcome this limitation. A perfect overlap resulting from the origin-symmetry of the encoded image enables polarization independent operation of geometric metasurfaces. The designed metasurface beam splitter is experimentally demonstrated by using hydrogenated amorphous silicon, and the device performs consistent beam splitting regardless of incident polarizations as well as wavelengths. Our device can be applied to generate equal-intensity beams for entangled photon light sources in quantum optics, and the design approach provides a way to develop ultra-thin broadband polarization independent components for modern optics.

Review of several precision finishing processes for optics manufacturing

The ultrasmooth optical components with atomic-order surface roughness and nanometre-level shape accuracy are in immense demand with the rapid advancement of modern optical technology. In recent years, aspherical and free-form surfaces are gaining more interest for its favorable properties. Moreover, the new optical materials with immensely enhanced mechanical properties are being developed to meet the stringent requirements of modern optics. Fabrication of complex-shaped ultrasmooth optical components becomes a significant challenge as conventional finishing techniques are unable to machine aspherical or free-form surfaces precisely. This situation demands some highly deterministic finishing processes. Mostly, the optical components are fabricated by shaping or pre-finishing methods followed by final finishing processes. In the shaping or pre-finishing methods, the rigid abrasive tools are used to remove the material at an enhanced rate and near net shape of the elements can be attained. Surface finish and shape accuracy can also be improved to some extent. Owing to the presence of residual finishing marks generated by shaping methods, the application of the components is limited to the infrared (IR) optics. Final finishing processes include more deterministic and flexible polishing techniques that can achieve desired surface finish, figure accuracy and surface integrity to make it suitable for shorter wavelength applications. In recent years, single point diamond turning, precision grinding, plasma chemical vaporization machining and magnetorheological fluid-based finishing are widely used for fabricating ultrasmooth optics. In this article, principle, mechanism of material removal and applicability of the aforementioned precision finishing processes to different materials are discussed.

Real-time observation of dissipative soliton formation in nonlinear polarization rotation mode-locked fibre lasers

Formation of coherent structures and patterns from unstable uniform state or noise is a fundamental physical phenomenon that occurs in various areas of science ranging from biology to astrophysics. Understanding of the underlying mechanisms of such processes can both improve our general interdisciplinary knowledge about complex nonlinear systems and lead to new practical engineering techniques. Modern optics with its high precision measurements offers excellent test-beds for studying complex nonlinear dynamics, though capturing transient rapid formation of optical solitons is technically challenging. Here we unveil the build-up of dissipative soliton in mode-locked fibre lasers using dispersive Fourier transform to measure spectral dynamics and employing autocorrelation analysis to investigate temporal evolution. Numerical simulations corroborate experimental observations, and indicate an underlying universality in the pulse formation. Statistical analysis identifies correlations and dependencies during the build-up phase. Our study may open up possibilities for real-time observation of various nonlinear structures in photonic systems.

Metasurface Enabled Wide-Angle Fourier Lens.

Fourier optics, the principle of using Fourier transformation to understand the functionalities of optical elements, lies at the heart of modern optics, and it has been widely applied to optical information processing, imaging, holography, etc. While a simple thin lens is capable of resolving Fourier components of an arbitrary optical wavefront, its operation is limited to near normal light incidence, i.e., the paraxial approximation, which puts a severe constraint on the resolvable Fourier domain. As a result, high-order Fourier components are lost, resulting in extinction of high-resolution information of an image. Other high numerical aperture Fourier lenses usually suffer from the bulky size and costly designs. Here, a dielectric metasurface consisting of high-aspect-ratio silicon waveguide array is demonstrated experimentally, which is capable of performing 1D Fourier transform for a large incident angle range and a broad operating bandwidth. Thus, the device significantly expands the operational Fourier space, benefitting from the large numerical aperture and negligible angular dispersion at large incident angles. The Fourier metasurface will not only facilitate efficient manipulation of spatial spectrum of free-space optical wavefront, but also be readily integrated into micro-optical platforms due to its compact size.

Measurement Technology as Enabler for Modern Optics

Measurement Technology as Enabler for Modern Optics

Controlling the Laser Guide Star power density distribution at Sodium layer by combining Pre-correction and Beam-shaping

The Sodium laser guide star (LGS) plays a key role in modern astronomical Adaptive Optics Systems (AOSs). The spot size and photon return of the Sodium LGS depend strongly on the laser power density distribution at the Sodium layer and thus affect the performance of the AOS. The power density distribution is degraded by turbulence in the uplink path, launch system aberrations, the beam quality of the laser, and so forth. Even without any aberrations, the TE00 Gaussian type is still not the optimal power density distribution to obtain the best balance between the measurement error and temporal error. To optimize and control the LGS power density distribution at the Sodium layer to an expected distribution type, a method that combines pre-correction and beam-shaping is proposed. A typical result shows that under strong turbulence (Fried parameter (r0) of 5 cm) and for a quasi-continuous wave Sodium laser (power (P) of 15 W), in the best case, our method can effectively optimize the distribution from the Gaussian type to the “top-hat” type and enhance the photon return flux of the Sodium LGS; at the same time, the total error of the AOS is decreased by 36% with our technique for a high power laser and poor seeing.

Nondiffracting light beams carrying fractional orbital angular momentum.

We investigate a new class of nondiffracting optical beams carrying fractional orbital angular momentum (FOAM Bessel beams), which can be constructed by modifying the phase step of the spiral phase plate in a setup originally for the generation of traditional Bessel beams. The FOAM Bessel beams have entirely stable vortex structures, and form an infinite number of orthogonal and complete subsets for monochromatic scalar light in free space. With the advantages of structural stability and orthogonality-completeness, the FOAM Bessel beams are expected to be useful for study and application in various fields of modern optics.

How to understand the tunneling in attosecond experiment?: Bohr–Einstein photon box Gedanken experiment, tunneling time and the wave particle duality

The measurement of the tunneling time (T-time) in today’s attosecond and strong field (low-frequency) experiments, despite its controversial discussion, offers a fruitful opportunity to understand time measurement and the time in quantum mechanics. In addition, as we will see in this work, a related controversial issue is the particulate nature of the radiation. The T-time in attosecond experiment and its different aspects and models, is discussed in this work, especially in relation to my model of real T-time (Kullie, 2015), where a good agreement with the experiment and an intriguing similarity to the Bohr–Einstein photon box Gedanken experiment was found. The tunneling process itself is still not well understood, but I am arguing that a scattering mechanism (by the laser wave packet) offers a possibility to understand the tunneling process in the tunneling region. This is related to the question about the corpuscular nature of light which is widely discussed in modern quantum optics experiments.

Trapping and guiding of large-size particles in hollow beams produced by nonlinear crystals

Since 1970, the trapping of the small objects in space by optical radiation pressure, such as nano particles and other atomic living cells, has been successfully developed and used in the applied physics, life sciences and other fields. As the optical radiation pressure is very weak, the use of radiation pressure on the particle will be strictly limited by the particle size. Also, the manipulated particles can move particle with only hundreds of microns. Therefore, it is not suitable for trapping and long-distance transporting particles with large size (micron). In recent years, with the development of the manipulation technology for large particles, a new control force-photophotetic force has gradually entered into people's vision field. Compared with the optical radiation pressure, the photophoretic force is much large under the same light intensity. Therefore, the photophoretic force makes it possible to manipulate and trap the large particles. With the development of laser beam-shaping technology, the species of laser beams become more and more abundant, which makes it more attractive to study particle manipulation based on the photophoretic force. For example, a hollow beam is used to capture and guide carbon nanoclusters in the air. A tapered optical fiber is used to trap, migrate and separate SiO2 particles. A Bessel Gaussian beam is used to trap and manipulate magnetic particles. An airy beam is used to trap glass carbon particles of absorption type. In this paper, a trapping and guiding scheme for large-size particles by using the photophoretic force of the hollow beams generated by nonlinear ZnSe crystals is proposed and analyzed theoretically. Our calculated results can be concluded as follows. 1) For the cases of two-dimensional particle trapping and one-dimentional particle guiding using a hollow beam generated by a single nonlinear ZnSe crystal, the magnitude of the longitudianl optical force is proportional to the ratio between particle size and hollow beam size to the fourth power and is proportional to the power of the hollow beam, and the direction is the same as that of the beam propagation. The closer to the hollow beam size the particle size, the greater the transverse optical force is. The results show that the photophoretic force can achieve the two-dimensional trapping of large-size particles, and a long distance (in a meter region) guiding. 2) For the case of three-dimensional particle trapping using a localized hollow beam generated by two nonlinear ZnSe crystals, the dependence of transverse photophoretic forceand that of longitudinal photophoretic force on the system parameters are similar to the scenario for the particles trapping in the hollow beam produced by a single nonlinear crystal. The difference is that under this condition, the direction of the longitudinal photophoretic force points to the center of the beam. So this scheme can achieve the effective three-dimensional trapping of large-size particles. Above all, the hollow beams generated by nonlinear ZnSe crystals can be used as an effective noncontact controlling tool for large-size particels, and might have potential applications in modern optics and biomedicine.

Simulations of return flux of polychromatic laser guide stars based on Bloch equations

Sodium laser guide star (LGS) becomes an essential part in modern astronomical adaptive optics system, especially for the next generation extremely large ground based telescope. The LGS technology has experienced the developmental stages as natural guide star, Rayleigh LGS, sodium LGS and constellation of LGS. The sky coverage is still limited in that the LGS cannot not be used to detect the tip/tilt aberrations. While the polychromatic laser guide star (PLGS) is one of the most effective ways to enlarge the sky coverage to 100%. Previous simulation models are insufficient for the accurate calculation of the return flux, especially for the simulation model of PLGS which is generated by one-photon excitation of mesospheric sodium atoms. The simulation model based on Bloch equations proposed in this paper can be used to compute the return flux of one-photon excited PLGS precisely. Doppler broadening, beam atom exchanging, collisions and recoil are taken into account in the model. The return flux is validated by the return efficiency. The simulation results indicate that with one-photon excitation of sodium atoms, a return efficiency of 330 nm is minimum compared with those of other wavelengths; the saturation power density will decrease with recoil increasing and increase with collision rate increasing; an optimal line-width exists up to maximum the photon return efficiency. In the best case, when the power density is 10 W/m2 at the sodium layer, the maximum return efficiency at 330 nm is 0.907 photons/s/sr/atom/(W/m2) with an optimal laser line-width of 18 MHz.

A. Mark Smith, From Sight to Light: The Passage from Ancient to Modern Optics. Chicago: University of Chicago Press, 2015, 2017, 480 pp., 41 halftones, 58 line drawings.

“Blessed are your eyes, for they see…” (Matt. 13: 16).

Fabrication of anti-reflective surfaces by 3-DOF fast tool servo diamond turning

Surface reflection existed in most optical elements that reduce the light transmission quality and bring down the optical system performance. Freeform optics is the key element in modern optics that it is strongly necessary to improve the anti-reflective performance. Therefore, the design and fabrication of anti-reflective freeform surfaces attract many researchers’ attention, and this paper proposed a 3-DOF pseudo random turning method for the fabrication. The core idea is that three-processed random signal is coupled to freeform surface normal turning toolpath, and the new toolpath takes the diamond tool do micro-vibration in three directions in the turning process to break down the periodic tool mark residual structure. This method is implemented by a 3-DOF fast tool servo (FTS) system. The cutting results show that the new toolpath can disrupt the periodic turning residual structures which have the anti-reflective property, and higher hardness material is conductive to the formation of surfaces microstructure. Better anti-reflective surfaces can be obtained by optimizing tool geometric parameters and cutting parameters.

Microfiber-coupled superconducting nanowire single-photon detector for near-infrared wavelengths.

High-performance superconducting nanowire single-photon detectors (SNSPDs) have facilitated numerous experiments and applications, particularly in the fields of modern quantum optics and quantum communication. Two kinds of optical coupling methods have thus far been developed for SNSPDs: one produces standard fiber-coupled SNSPDs in which the fibers vertically illuminate the meandered nanowires; the other produces waveguide-coupled SNSPDs in which nanowires are fabricated on the surface of a waveguide that guides photons, and the fibers are coupled to the waveguide. In this paper, we report on first experimental demonstration of a new type of SNSPD that is coupled with a microfiber (MF). Photons are guided by the MF and are evanescently absorbed by the nanowires of the SNSPD when the MF is placed on top of superconducting NbN nanowires. Room-temperature optical experiments indicated that this device has a coupling efficiency of up to 90% when a 1.3 μm-diameter MF is used for light with wavelength of 1550 nm. We were also able to demonstrate that our MF-coupled detector achieved system detection efficiencies of 50% and 20% at incident wavelengths of 1064 and 1550 nm, respectively, for a 2 μm-diameter MF at 2.2K. We expect that MF-coupled SNSPDs may show both high efficiency and broadband characteristics upon optimization and will be used for various novel applications, such as micro/nano-fiber optics.

Self-assembling peptide semiconductors.

Semiconductors are central to the modern electronics and optics industries. Conventional semiconductive materials bear inherent limitations, especially in emerging fields such as interfacing with biological systems and bottom-up fabrication. A promising candidate for bioinspired and durable nanoscale semiconductors is the family of self-assembled nanostructures comprising short peptides. The highly ordered and directional intermolecular π-π interactions and hydrogen-bonding network allow the formation of quantum confined structures within the peptide self-assemblies, thus decreasing the band gaps of the superstructures into semiconductor regions. As a result of the diverse architectures and ease of modification of peptide self-assemblies, their semiconductivity can be readily tuned, doped, and functionalized. Therefore, this family of electroactive supramolecular materials may bridge the gap between the inorganic semiconductor world and biological systems.

White light Sagnac interferometer—a common (path) tale of light

White or polychromatic light sources are vastly abundant in nature and lie in our most basic understanding of the theory of light, beginning from stars like our Sun and extending to every common household light bulb or street lamp. In this paper, I present concepts of white light interferometery using a common-path Sagnac interferometer, manifested in a straightforward laboratory experiment. I further show the use of this as a Fourier transform spectrometer while presenting a basic overview of the theoretical concepts and spectrum of different light sources obtained experimentally. This work, both experimentally and analytically, is suitable for upper-level undergraduate physics or engineering courses where electromagnetic theory and optics are discussed. The experiment and theory presents important deep concepts and aspects in modern optics and physics that every science student should acquire.

Design of metasurface polarizers based on two-dimensional cold atomic arrays.

Engineering light-matter interaction using cold atomic arrays is one of the central topics in modern optics. Here we have demonstrated the capability of two-dimensional asymmetric cold atomic arrays as microscopic metasurfaces for controlling polarization states of light. The designed linear polarizer can lead to an extinction ratio over 20dB as well as a high transmittance over 0.8 for the permitted polarization at zero detuning. For detuned driving light, changing lattice constants can also achieve high performance linear polarizers. We have also accomplished a circular polarizer by manipulating the phases of transmitted light. A theoretical analysis based on Bloch theorem shows the underlying mechanism for this performance is actually attributed to cooperative effects in periodic lattices. Finally, we discuss in detail the effects of system size, lattice imperfection and nonzero driving light linewidth in practical implementation. The present study paves a way to design extremely miniaturized metasurfaces using cold atoms and other two-level systems, showing great potential in quantum information and quantum metrology sciences as well as the fundamental physics of light-matter interaction.

Simple method for efficient reconfigurable optical vortex beam splitting.

In recent years, singular light beams with orbital angular momentum are one of the most striking examples of structured light that have been widely applied in modern science. The transition from the generation of a single vortex beam to the generation of multiple such beams progressed the development of singular optics. This paper presents a new efficient method of vortex laser beam splitting using a two-level pure-phase diffractive optical element. The proposed compact element, which can be easily implemented with a low-cost binary spatial light modulator or fabricated by electron beam lithography or photolithography, is a useful tool for the reconfigurable generation of multiple closed-packed vortex beams. Furthermore, the proposed splitter can efficiently operate in the wavelength range of approximately 8% of the central wavelength, thus providing an efficient method to generate optical vortex arrays with various potential applications in modern optics and photonics.

Q-switched Erbium-doped Fiber Laser with a Black Phosphorus Saturable Absorber

A passively Q-switched Erbium-doped fiber laser (EDFL) is demonstrated using a black phosphorus saturable absorber as the Q-switcher. The laser generates a stable pulse operating at a wavelength of 1562.35 nm within a pump power region from 7.2 mW to 42.3 mW. At 980 nm pump power of 42.3 mW, the EDFL generates an optical pulse train with a repetition rate of 44.72 kHz and pulse width of 9.8 us. The maximum pulse energy of 81.5 nJ is obtained at a pump power of 35.2 mW. A higher performance Q-switched EDFL is expected to be achieved with the optimization of the saturable absorber and laser cavity. Full Text: PDF ReferencesR. Mas-Balleste, C. Gomez-Navarro, J. Gomez-Herrero and F. Zamora, "2D materials: to graphene and beyond", Nanoscale 3, 20 (2011). CrossRef Z. Sun, T. Hasan, F. Torrisi, D. Popa, G. Privitera, F. Wang, F. Bonaccorso, D. M. Basko and A. C. Ferrari, "Graphene Mode-Locked Ultrafast Laser", ACS nano 4, 803 (2010) CrossRef F. Xia, H. Wang and Y. Jia, "Rediscovering black phosphorus as an anisotropic layered material for optoelectronics and electronics.", Nat Commun 5 (2014). CrossRef G. Sobon, "Mode-locking of fiber lasers using novel two-dimensional nanomaterials: graphene and topological insulators [Invited]", Photonics Research 3, A56 (2015). CrossRef Y. Chen, G. Jiang, S. Chen, Z. Guo, X. Yu, C. Zhao, H. Zhang, Q. Bao, S. Wen and D. Tang, "Mechanically exfoliated black phosphorus as a new saturable absorber for both Q-switching and Mode-locking laser operation", Optics express 23, 12823 (2015). CrossRef M. Hisyam, M. Rusdi, A. Latiff and S. Harun, "Generation of Mode-Locked Ytterbium Doped Fiber Ring Laser Using Few-Layer Black Phosphorus as a Saturable Absorber", IEEE Journal of Selected Topics in Quantum Electronics 23, 39 (2017). CrossRef S. Sugai and I. Shirotani, "Raman and infrared reflection spectroscopy in black phosphorus", Solid state communications 53, 753 (1985). CrossRef Z.-C. Luo, M. Liu, Z.-N. Guo, X.-F. Jiang, A.-P. Luo, C.-J. Zhao, X.-F. Yu, W.-C. Xu and H. Zhang, "Microfiber-based few-layer black phosphorus saturable absorber for ultra-fast fiber laser", Optics express 23, 20030 (2015). CrossRef A. Latiff, M. Rusdi, M. Hisyam, H. Ahmad and S. Harun, "A generation of 2 um Q-switched thulium-doped fibre laser based on anatase titanium(IV) oxide film saturable absorber", Journal of Modern Optics 64, 187 (2017). CrossRef J. Bogusławski, G. Soboń, K. Tarnowski, R. Zybała, K. Mars, A. Mikuła, K. M. Abramski and J. Sotor, "All-polarization-maintaining-fiber laser Q-switched by evanescent field interaction with Sb2Te3 saturable absorber", Optical Engineering 55, 081316 (2016). CrossRef Z. Wang, Y. Xu, S. C. Dhanabalan, J. Sophia, C. Zhao, C. Xu, Y. Xiang, J. Li, and H. Zhang, "Black Phosphorus Quantum Dots as an Efficient Saturable Absorber for Bound Soliton Operation in an Erbium Doped Fiber Laser," IEEE Photonics Journal 8, 1 (2016). CrossRef