One-dimensional Photonic Structures Research Articles

Photon-pair generation in nonlinear metal-dielectric one-dimensional photonic structures

Nonlinear metal-dielectric layered structures are shown to be able to efficiently generate entangled photon pairs using spontaneous parametric down-conversion. Increase of electric-field amplitudes in these structures enhanced by the presence of metal layers is sufficient to compensate for losses inside thin metal layers. As an example, photon pairs emitted from a structure composed of alternating nonlinear dielectric GaN layers and metal Ag layers are analyzed in spectral, temporal, as well as spatial domains. Also, correlations and entanglement between two photons in a pair are determined. Very narrow photon-pair spectra together with strong directionality of photon-pair emission are observed making the photons suitable for photon-atom interactions. Highly enhanced electric-field amplitudes provide high photon-pair generation efficiencies.

Theoretical demonstration of GaAs/AlAs optically confined double photonic structure for THz generation

We theoretically propose GaAs/AlAs composite double photonic structures for widely tunable THz generation with efficient power, on the basis of difference frequency generation. The wide tunability is achieved by using form birefringence of the one-dimensional photonic structure, where we demonstrate tunability with 0.5–1.4, 1.5–2.4, or 5.4–6.5 THz. The estimated THz powers can reach the order of µW in the entire frequency region. The proposed scheme will be a powerful candidate for realizing a THz source for high-resolution spectroscopic systems.

Fluorescence excitation enhancement by Bloch surface wave in all-polymer one-dimensional photonic structure

We demonstrate photoluminescence excitation enhancement in an all-polymer flexible one-dimensional photonic crystal structure capped with a fluorescent organic ultrathin film. When optical matching conditions between the excitation beam and the Bloch Surface Wave mode supported by the photonic structure are achieved, a ten times enhancement of the photoluminescence is observed. We notice that in these systems luminescence signal reinforcement is achieved by increasing the pump efficiency with no need of spectral resonance to the emission of the chosen fluorophore. All these features make these systems suitable candidates for easy, flexible, and cheap fluorescent sensing.

Tunable omni-directional mirror based on one-dimensional photonic structure using twisted nematic liquid crystal: the anchoring effects

We present the tunability of the omnidirectional band gap (OBG) in a one-dimensional photonic structure consisting of N nematic liquid-crystal slabs in a twisted configuration. It is alternated by N isotropic dielectric layers by a dc electric field aligned along the periodicity axis. We consider the general case for which arbitrary anchoring of the nematic at the boundaries is taken into account. The threshold electric field for which the OBG is created decreases as the anchoring strength diminishes. The width of this band gets larger as the electric field increases and its center frequency is modified slightly.

Ultralow-threshold single-mode lasing based on a one-dimensional asymmetric photonic bandgap structure with liquid crystal as a defect layer.

In this Letter, we propose defect-mode lasing from a one-dimensional asymmetric photonic structure with dye-doped nematic liquid crystal as a central defect layer. The local field intensity of the distinguished single defect mode at the overlapped photonic band edges is drastically enhanced by the asymmetric structure consisting of two distinct multilayer photonic crystals. With high density of states of photons, effective output lasing emission and maximum input excitation are ensured. As a result, the single-mode lasing with a low excitation threshold of 0.2 μJ/pulse is achieved due to the combination of the defect layer and the photonic band edge effect.

Asymmetric bistable reflection and polarization switching in a magnetic nonlinear multilayer structure

Optical properties of one-dimensional photonic structures consisting of Kerr-type nonlinear and magnetic layers under the action of an external static magnetic field in the Faraday geometry are investigated. The structure is a periodic arrangement of alternating nonlinear and magnetic layers (a one-dimensional photonic crystal) with one of the layers doubled to create a defect where periodicity is violated. Strong enhancement of nonreciprocity is observed at the frequencies of the defect modes, where linearly polarized light incident from one side of the structure undergoes polarization rotation upon reflection, while light reflected from the other side has its polarization unchanged. Using the nonlinear transfer matrix calculations in the frequency domain, it is demonstrated that defect resonances in the nonlinear reflection spectra undergo bending, resulting in polarization bistability of reflected light. This bistability is shown to result in abrupt switching between linear polarization of the output reflected light when the input intensity is varied. This switching is confirmed in finite-difference time-domain simulations, and its hysteresis character is established.

One-dimensional photonic structure with multilayer random defect

A photonic structure composed of two dielectric mirrors with a random multilayer defect embedded is presented. Simulating the transmission spectra of 30,028 permutations of the random defect with the transfer matrix method, we have observed defect lines in the photonic bad gap region, with intensity and spectral position depending on the different permutations. We have compared their optical properties with the ones of two types of structures: (i) conventional defect and (ii) periodic multilayer defect photonic structures. We have noticed that about 15% of the random defect structures, showing very intense defect peaks in the photonic band gap region, exhibit total light transmission in such range of wavelengths that is higher with respect to the other structures. Moreover, random defect structures can show two defect lines with relatively high transmission maxima, in spite of the only one defect line or the two weak defect lines of the other multilayer sequences. These results can be interesting for the fabrication of one- or two-colour photonic crystal defect lasers, with an appropriate choice of random defect sequences and emitting media.

Defect modes properties in self-similar fractal multilayer structures containing lossless single negative metamaterials

Transfer matrix method is used to investigate the electromagnetic transmission spectra of a one-dimensional photonic fractal multilayer structure composed of single-negative metamaterial when common positive dielectric defect layers of are introduced. It is found that the frequency of the resonance defect modes can be tuned independently by varying the defect layer thicknesses. It is also found that by increasing the value of refractive index of defect layers and the number of periods, the full width half maximum of defect modes will be narrowed and shifted to lower frequencies. Also, our investigations show that for both TE and TM polarizations moving away from normal incidence to oblique incidence shows that the defect modes shift to upper frequencies. In other words, the defect modes inside the band gap depend on the incident angle and polarization. More interesting, for angles of incidence greater than 55° the defect modes for TE polarization (unlike to TM polarization) are eliminated. Moreover, the electromagnetic fields in the defect layers are strongly localized, and they can be excite independently. We believe that the proposed fractal structures can be useful in designing tunable independently high-Q filters with specific channels by adjusting their structural parameters.

Microstructure, optimum pigment content and low infrared emissivity of polyurethane/Ag composite coatings

Polyurethane (PU)/Ag composite coatings with low infrared emissivity were successfully prepared by using PU and flaky Ag powders as adhesives and pigments, respectively. The infrared emissivity and microstructure of as-prepared products were systematically investigated by infrared emissometer and scanning electron microscopy, respectively. Infrared emissivity measurement shows that the emissivity of the coatings approaches the lowest value of 0.082 at the wavelength of 8–14µm when the Ag content is about 20wt%. Microstructure observation shows that the coatings have similar one-dimensional photonic structural characteristics. According to the structural characteristics, a simulation method for optimum pigment content and the cause of low infrared emissivity of the coatings were successfully obtained and discussed by using the theories of one-dimensional photonic structure, respectively. The results indicate that the low infrared emissivity of PU/Ag composite coatings is derived from the similar one-dimensional photonic structure in the coatings, and the calculated optimum Ag content is in good agreement with the experimental value, which reveals that it is a practical simulation method for optimum pigment content of low infrared emissivity composite coatings.

Theoretical demonstration of highly efficient cw THz generation by using composite photonic-structure elements

We theoretically propose one-dimensional composite photonic structures for high-resolution THz spectroanalysis. We compare the performance of two GaAs/AlAs composite photonic-structure devices, one with usual 1/4-wavelength layers of distributed Bragg reflectors (DBRs), and the other with the designed DBRs. The device with designed DBRs shows the optical-to-terahertz conversion efficiency up to 10−5 and wide frequency tunability ranging from sub-THz to 3 THz. We found that the composite photonic structure allows us to control photonic modes with a high degree of freedom by flexible structure designs. This device achieve a cw THz source with a highly narrow bandwidth operating at room temperature.

Study of highly broadening Photonic band gaps extension in onedimensional Metallo-organic multilayer Photonic structure

In this paper, we show theoretically that the reflectance spectra of one dimensional multilayer metal- organic periodic structure (1D MOPS) can be enhanced due to the addition of the organic constituents. We have used simple transfer matrix method to calculate the absorption, transmittance and reflectance of the 1D MOPS systems. The organic component like N,N'-bis-(1-naphthyl)-N,N'diphenyl-1; 1biphenyl-4; 4diamine (NPB) absorbs the light in ultra-violet, visible and infrared electromagnetic region and the structure with Ag- metal also having the tendency to absorb the light by the plasmaonic action and their refractive can be calculated from Drude equation. The reflectance spectra of multilayer 1D MOPS containing a variable number periodic of Ag/N,N'-bis-(1-naphthyl)-N,N'diphenyl-1; 1biphenyl-4; 4diamine (NPB) structure are calculated taking optical constant of NPB and Ag. The optical band gap and reflectance spectra of 1D MOPS of the considered structure is obtained in the visible and near infrared regions either with the variation of the metal layer thickness or thickness of the organic layer. From the results under investigation through TMM, tunability in the optical band gap was observed either change in thickness of the other layer 1/ or 2 or the angle of the incident. Due to optical absorption of the light in the different region of electromagnetic spectrum due to either N,N'-bis-(1-naphthyl)-N,N'diphenyl-1; 1biphenyl-4; 4diamine (NPB) or silver metal, the optical band gap of 1DMOPS shows the shift of band edges of λL and λR from ultra-violet to visible and the infrared with change the optical constant. Keywords - Photonic crystals, Dielectric and organic layer, TE and TM mode

Nacre biomimetic design—A possible approach to prepare low infrared emissivity composite coatings

Mimicking the highly organized brick-and-mortar structure of nacre, a kind of nacre-like organic–inorganic composite material of polyurethane (PU)/flaky bronze composite coatings with low infrared emissivity was successfully designed and prepared by using PU and flaky bronze powders as adhesives and pigments, respectively. The infrared emissivity and microstructure of the coatings were systematically investigated by infrared emissometer and scanning electron microscopy, respectively, and the cause of low infrared emissivity of the coatings was discussed by using the theories of one-dimensional photonic structure. The results show that the infrared emissivity of the nacre-like PU/flaky bronze composite coatings can be as low as 0.206 at the bronze content of 60wt. %, and it is significantly lower than the value of PU/sphere bronze composite coatings. Microstructure observation illustrated that the nacre-like PU/flaky bronze composite coatings have similar one-dimensional photonic structural characteristics. The low infrared emissivity of PU/flaky bronze composite coatings is derived from the similar one-dimensional photonic structure in the coatings.

Omnidirectional band gaps in quasiperiodic photonic crystals in the THz region

In this work we calculate the emittance spectra of the electromagnetic radiation normally and obliquely incident (s- and p-polarized modes) on a one-dimensional multilayer quasiperiodic photonic structure made up by layered system of positive (SiO2) and negative (LiTaO3) refractive index materials organized in a quasiperiodic (Fibonacci-like) fashion. We model the negative refractive index material by an effective medium, whose electric permittivity ϵ(ω) is characterized by a phonon-polariton frequency dependent dielectric function, while for the magnetic permeability μ(ω) we have a Drude-like frequency-dependent function. The emittance spectra are determined by means of a well known theoretical model based on Kirchoff’s second law, together with a transfer matrix formalism. Our results shows that the omnidirectional band gaps appear in the THz regime, in well defined frequency intervals independently of the electromagnetic radiation’s polarized modes.

Study of the omnidirectional photonic bandgap for dielectric mirrors based on porous silicon: effect of optical and physical thickness

We report the theoretical comparison of the omnidirectional photonic bandgap (OPBG) of one-dimensional dielectric photonic structures, using three different refractive index profiles: sinusoidal, Gaussian, and Bragg. For different values of physical thickness (PT) and optical thickness (OT), the tunability of the OPBG of each profile is shown to depend on the maximum/minimum refractive indices. With an increase in the value of the maximum refractive index, the structures with the same PT showed a linear increment of the OPBG, in contrast to the structures with the same OT, showing an optimal combination of refractive indices for each structure to generate the maximum OPBG. An experimental verification was carried out with a multilayered dielectric porous silicon structure for all the three profiles.

Carrier dynamics of the intermediate state in InAs/GaAs quantum dots coupled in a photonic cavity under two-photon excitation

We have studied the time-resolved intraband transition from the intermediate state to the continuum state of the conduction band in InAs/GaAs self-assembled quantum dots (QDs) embedded in a one-dimensional photonic cavity structure using two-color photoexcitation spectroscopy. The resonant energy of the photonic cavity was tuned to enhance the intraband transition with an energy smaller than the interband transition energy between the intermediate state and the quantized hole states. The interband photoluminescence intensity was observed to be drastically reduced due to the pumping out of carriers in the intermediate state using near-infrared laser light. We proposed a model describing the carrier relaxation process in the InAs/GaAs QD system, where the two-photon absorption and the Pauli blocking in QDs are considered.

Electric Field Controlled Optical and Magneto-Optical Effects at Light Transmission Through a One-Dimensional Magnetic Photonic Structure with Complex Defect Layer

One-dimensional magnetic photonic crystal with electro-optic and magneto-optic defect layers has been studied. The influence of the defect layers position inside a photonic crystal, as well as an action of a DC external electric field on the transmittivity spectra and Faraday rotation is investigated theoretically, taking into account the frequency dispersion of the system permittivities.

Omnidirectional photonic bangap in dielectric mirrors: a comparative study

We report the theoretical comparison of the omnidirectional photonic band gap (OPBG) of one-dimensional dielectric photonic structures, using three different refractive index profiles: sinusoidal, Gaussian and Bragg. For different values of optical thickness, the tunability of the OPBG of each profile is shown to depend on the maximum, minimum and the difference of the refractive indices. An experimental verification was carried out with a multilayered dielectric porous silicon structure for all the three profiles. The optimal combination of refractive indices for each structure which generates the maximum OPBG has also been calculated. Such study can be useful to design the required OPBG structures for photonic applications.

Multiple narrow bandpass optical filters based on one-dimensional rugate photonic structures of two periodicities

A theoretical analysis of a design of multiple narrow bandpass filters based on one-dimensional (1D) rugate photonic structures with a period jump defect is presented. The optical properties, including transmittance and energy density distributions, are numerically calculated using the propagation matrix method. Our results show that multiple resonance transmission modes are produced when the period jump defect is introduced into the 1D rugate film. Both blueshift and redshift of the stop band of the rugate structure and wavelengths of resonant modes are observed, depending on the change of period jump. The number, the wavelengths, the band intervals, and the intensities of multiple resonance transmission modes are tunable by adjusting structure parameters of the rugate structure. Experimental feasibility of the proposed multiple narrow bandpass optical filters using the technique of glancing angle deposition is also discussed.

PHASE SHIFT DEFECT MODES IN ONE-DIMENSIONAL ASYMMETRICAL PHOTONIC STRUCTURES CONSISTING OF TWO RUGATE SEGMENTS WITH DIFFERENT PERIODICITIES

A theoretical study of optical properties of phase shift defects in one-dimensional asymmetrical photonic structures consisting of two rugate segments with difierent periodicities at both normal and oblique incidence is presented. Using the propagation matrix method we numerically calculated transmittance spectra, defect wavelengths, energy density distributions, and group velocities for TE and TM waves, respectively. Our study shows that by adjusting the periodicity of one rugate segment, the defect wavelengths can be shifted toward either a shorter wavelength or a longer wavelength. The difierences of the energy density distributions of TE and TM waves at difierent angles of incidence are explained with the help of group velocity. Efiects of the change of the period of one rugate segment on the peak energy densities of defect modes and minimum group velocities at difierent angles of incidence are also investigated.

PROPERTIES OF PHASE SHIFT DEFECTS IN ONE-DIMENSIONAL RUGATE PHOTONIC STRUCTURES

We theoretically investigated optical properties of phase shift defects in one-dimensional rugate photonic structures at oblique incidence. Transmission spectra and energy density distributions of such continuous gradient-index structures with phase shift defects were numerically calculated for TE and TM waves using the propagation matrix method. The study shows that when the angle of incidence increases, (1) the wavelength of the defect mode shifts to a shorter wavelength, (2) the stop band of the rugate structure moves toward a shorter wavelength region, (3) the bandwidth is enlarged for TE wave, but it is shortened for TM wave, (4) the full width at half maximum (FWHM) of the defect mode decreases for TE wave but it increases for TM wave, (5) the peak energy density increases and then drops for TE wave, while it always decreases for TM wave. The efiect of number of periods of rugate structures on the energy density distribution was also examined.