Frequency Of Incident Light Research Articles

Two-plasmon-decay instability in the non-eigenmode regime in laser–plasma interaction

It is shown theoretically that the two-plasmon-decay instability (TPD) in laser–plasma interaction can be excited in the non-eigenmode regime, where the plasma density is larger than the quarter critical density. This appears when the laser amplitude is larger than a certain threshold value, which is found to increase with the plasma density. In this regime, the excited electrostatic modes have a constant frequency around half of the incident light frequency. The theoretical model is validated by particle-in-cell simulations. The simulation results show that the non-eigenmode TPD has a higher threshold amplitude for the pump laser than the non-eigenmode stimulated Raman scattering (SRS) excited in the plasma above the quarter critical density. In inhomogeneous plasma, competition between non-eigenmode TPD and non-eigenmode SRS occurs since the excitation of the former is normally accompanied by the latter.

Distribution of Single-Particle Resonances Determines the Plasmonic Response of Disordered Nanoparticle Ensembles.

Understanding how colloidal soft materials interact with light is crucial to the rational design of optical metamaterials. Electromagnetic simulations are computationally expensive and have primarily been limited to model systems described by a small number of particles-dimers, small clusters, and small periodic unit cells of superlattices. In this work we study the optical properties of bulk, disordered materials comprising a large number of plasmonic colloidal nanoparticles using Brownian dynamics simulations and the mutual polarization method. We investigate the far-field and near-field optical properties of both colloidal fluids and gels, which require thousands of nanoparticles to describe statistically. We show that these disordered materials exhibit a distribution of particle-level plasmonic resonance frequencies that determines their ensemble optical response. Nanoparticles with similar resonant frequencies form anisotropic and oriented clusters embedded within the otherwise isotropic and disordered microstructures. These collectively resonating morphologies can be tuned with the frequency and polarization of incident light. Knowledge of particle resonant distributions may help to interpret and compare the optical responses of different colloidal structures, correlate and predict optical properties, and rationally design soft materials for applications harnessing light.

External electric field assisted energy band gap modulation and optical properties of SiGe/AsSb heterobilayers

In this work, first-principle calculations within Density Functional Theory (DFT) were performed to study the structural, electronic, and optical properties of eight different bilayer van der Waals (vdW) heterostructures composed of SiGe and AsSb monolayers. These heterobilayers exhibit large energy bandgap (90 meV–459 meV) with linear energy–momentum relationship, implying high charge carrier mobility. Application of external vertical electric field can effectively modulate the energy bandgap of these heterobilayers from 64 meV to 459 meV, depending on stacking orders. Our study shows that a moderate amount of electric field can almost linearly tune the energy bandgap, however, semiconductor to metal transition occurs beyond a certain limit. The mechanism of energy bandgap tuning by the external electric field was examined by studying differential charge density. The optical properties such as complex dielectric function, electron energy loss function, complex refractive index, reflectivity, absorption coefficient, and optical conductivity of these SiGe/AsSb heterobilayers are studied for parallelly and perpendicularly polarized incident light. Our research demonstrates that these heterostructures exhibit variable plasma frequency depending on the stacking order of the heterostructures, anisotropic reflectivity i.e., birefringence properties in response to the incident light's polarization. Also, they exhibit high refractive indices (∼3) and absorption coefficients (∼105 cm−1) from visible to ultraviolet incident light frequencies. Our study proposes several SiGe/AsSb heterobilayers with unique electronic and optical properties which may have potential applications in nanoscale electronic and optoelectronic applications.

Nonlinear Photodetector Based on InSe p–n Homojunction for Improving Spatial Imaging Resolution

AbstractAn efficient nonlinear photodetector (NLPD) is demonstrated with quadratic response based on a few‐layer InSe p–n homojunction, which is beneficial from the strong second harmonic generation (SHG) process in InSe and effective harvest of photocarriers actuated by the high‐quality homojunction. The NLPD can sense light with photon energy smaller than InSe's electronic bandgap because the SHG process in InSe doubles the frequency of incident light, extending InSe's photodetection wavelength range to 1750 nm. The InSe p–n homojunction, which is electrostatically doped by two split back gates, presents a rectification ratio exceeding 106 with a dark current down to 2 pA and a high normalized responsivity of 0.534 A W−2 for the telecom‐band pulsed light at 1550 nm. The photocurrents of the SHG‐assisted photodetection have a quadratic dependence on the optical powers, making the NLPD highly sensitive to light intensity variation with improved spatial resolution. As examples, the NLPD is employed to precisely determine the localization point of a focused laser beam waist and implement spatial imaging with an improved resolution compared with the linear photodetector. These features highlight the potential of the proposed NLPD in developing advanced optical sensing and imaging systems.

Artificial Retina Based on Organic Heterojunction Transistors for Mobile Recognition.

The flicker frequency of incident light constitutes a critical determinant in biology. Nevertheless, the exploration of methods to simulate external light stimuli with varying frequencies and develop artificial retinal neurons capable of responsive behavior remains an open question. This study presents an artificial neuron comprising organic phototransistors. The triggering properties of neurons are modulated by optical input, enabling them to execute rudimentary synaptic functions, emulating the biological characteristics of retinal neurons. The artificial retinal neuron exhibits varying responses to incoming light frequencies, allowing it to replicate the persistent visual behavior of the human eye and facilitating image discrimination. Additionally, through seamless integration with circuitry, it can execute motion recognition on a machine cart, preventing collisions with high-speed obstacles. The artificial retinal neuron offers a cost-effective and energy-efficient route for future mobile robot processors.

Controlling the propagation asymmetry of hyperbolic shear polaritons in beta-gallium oxide

Structural anisotropy in crystals is crucial for controlling light propagation, particularly in the infrared spectral regime where optical frequencies overlap with crystalline lattice resonances, enabling light-matter coupled quasiparticles called phonon polaritons (PhPs). Exploring PhPs in anisotropic materials like hBN and MoO3 has led to advancements in light confinement and manipulation. In a recent study, PhPs in the monoclinic crystal β-Ga2O3 (bGO) were shown to exhibit strongly asymmetric propagation with a frequency dispersive optical axis. Here, using scanning near-field optical microscopy (s-SNOM), we directly image the symmetry-broken propagation of hyperbolic shear polaritons in bGO. Further, we demonstrate the control and enhancement of shear-induced propagation asymmetry by varying the incident laser orientation and polariton momentum using different sizes of nano-antennas. Finally, we observe significant rotation of the hyperbola axis by changing the frequency of incident light. Our findings lay the groundwork for the widespread utilization and implementation of polaritons in low-symmetry crystals.

Electronic band structures and optical properties of 2D XOF (X = Ga or In) oxyfluoride monolayers using density functional theory and GW approximation

The class of two-dimensional oxyfluoride monolayers is currently considered one of the most attractive nanomaterials for enhancing design and pushing the limits of different cutting-edge technologies. Two-dimensional semiconductor materials are the most promising systems for various applications in optoelectronic devices because they have a unique optical properties. We continue in this way by investigating the GW band structures and optical properties of unique 2D XOF (X = Ga or In) oxyfluoride monolayers, involving absorption, conductivity, refractive index, and dielectric function. We find no imaginary frequencies in the computed phonon spectra, indicating that these systems are dynamically stable. Furthermore, GaOF and InOF stay stable for temperatures T ≤ 840 K. The band gap of GaOF obtained with the single shot (G0W0) is larger than the band gap energy Eg of InOF. Where the direct band gap energies of GaOF and InOF are 6.1 eV and 4.8 eV, respectively. Our GW(PBE) numerical simulations demonstrate that the GaOF monolayer moves transparent once the frequency of the incoming light exceeds the plasma frequency (35.00 eV). Furthermore, InOF switches transparently once the incident light frequency exceeds the plasma frequency ∼ 35.00 eV. Interestingly, we obtain that these 2D sheets have a strong absorption coefficient in the range of ∼ 3.00–60.00 eV. They are emerging as a potential for the building blocks of the nano-size and ultra-thin optoelectronics of the future since they productively emit and absorb light.

Energy transport and relaxation of phonon polaritons in two-dimensional polar crystals

Energy transport and relaxation of phonon polaritons (PhPs) are studied, based on a macroscopic phonon model, for atomic layers of hexagonal boron nitride (hBN) and transition metal dichalcogenides (TMDs). The velocity of the energy flow (energy velocity) is derived from the energy flow and density; it equals the group velocity, similar to the results of bulk and surface PhPs. In electrostatic approximation, valid once the frequency is slightly above ω0 (e.g., ω>1.002ω0∼224cm−1 for pentalayer MoTe2; ω0 is the zone-center optical-phonon frequency), simple formulas are obtained for the energy velocity and relaxation rate (ERR). While the energy velocity increases proportionally with the number of layers N, the ERR is independent of N. The ERR equals the phonon damping rate in freestanding layers, but it is slightly decreased in SiO2-supported layers and has a non-monotonic frequency dependence (the decrease is smaller than 5.4% for hBN layers and negligible for TMD layers). The energy velocity decreases significantly with frequency in both freestanding and supported layers. Near ω0, however, the PhP properties should be calculated rigorously, and they all depend on N as well as the dielectric environment. High-frequency screening should be included to study the energy transport. The energy velocity can be engineered by varying N and the dielectric environment; it also can be tuned together with the propagation quality factor by the incident light frequency. The MoTe2 layers should be exploited for a far-infrared PhP material (wavelengths 43–45 μm); this is just an example of application of the proposed model to the considered materials.

Focusing of Hyperbolic Phonon Polaritons by Bent Metal Nanowires and Their Polarization Dependence

Manipulating in-plane hyperbolic phonon polaritons on biaxial van der Waals crystals provides an opportunity for the development of planar photonic devices. Recent studies show that nanometal disks constructed on the surface of hyperbolic media can focus phonon polaritons, which is a remarkable breakthrough in planar photonics. Here, we demonstrate that using bent metal nanowires made by strain engineering not only produces the focusing of hyperbolic phonon polaritons but also introduces a new modulation factor, the polarization of incident light, which shows a clear affection on focusing. In this study, we investigate the operating mechanism and applicability of this nanolens from the perspective of device size, incident light frequency, and polarization, where the effect of polarization is unprecedented for this type of surface engineering. With the support of super-resolution technology, the foci with high confinement are clearly observed and the focal length from 0.7 to 2.01 μm is achieved. Moreover, the angle between the in-plane polarization direction and the axial direction of the nanowires directly affects the intensity of the local field. This approach provides a new idea to control electromagnetic fields in a two-dimensional plane, which is beneficial to further promote the design of planar optical functional devices.

Optomechanical Heating and Cooling via Tip-Enhanced Raman Scattering in Epsilon-Near-Zero Medium

Media with the dielectric permittivityclose to zero (epsilon-near-zero or ENZ) maintain conditions for enhanced light-matter interactions. In this paper, we propose to use these media to enhance the optomechanical coupling of vibrational excitations of the medium with the optical near-field of the nanoantenna. It is shown that the ENZ medium significantly increases the optically induced decay rate of a vibration, which can be used for cooling (when the incident light frequency is less than the ENZ frequency) or heating (when the incident light frequency is greater than the ENZ frequency). Due to the proximity of the refractive index to zero as well, oscillations of the polarization of the medium are coherent, which further enhances the optomechanical effects. Analytical expressions are obtained for the optical shift of the resonance and the induced decay rate.

Near-perfect wide-band absorbers based onone-dimensional photonic crystal structures in1-20 THz frequencies.

This paper investigates the absorption behavior of one-dimensional (1D) photonic crystal (PhC) structures in the 1-20THz region. The structures are analyzed by the transfer matrix method to achieve accurate results quickly with ordinary simulation facilities. The simulation results indicate a strong dependence of the absorber performance on the thickness and material of the PhC layers, as well as the frequency and angle of incident light. The combination of silica and titanium (Ti) materials as dielectric and metal layers presents a great choice for broadband high-absorption applications so that this structure can absorb, on average, more than 80% of the normal incident radiation in the studied frequency range. Additionally, this absorber has the lowest dependence on incident light with the angle varying from 0° to 80° compared to identical absorbers with silver, aluminum, gold, chromium, nickel, and tungsten metals. The excellent absorption feature of the Ti-based absorber compared to the other absorbers is attributed to the lower permittivity of Ti (in both real and imaginary parts) in comparison with the other metals. In addition to owning simple and fabrication-friendly structures, 1D PhCs can pave the way to achieve various absorption spectra proportional to the needs of photonics, communications, and aerospace applications.

First-principles study of electronic and optical properties of novel 2D TiOS monolayer and bilayer—Dimensionality reduction opens up a band gap in TiOS

The finding of advanced functional materials with superior properties to existing ones to develop cutting-edge technologies for societal advancement is indispensable. We identify a new two-dimensional (2D) TiOS, which opens up a band gap due to the lowering of the dimensionality employing first-principles computations within the framework of density functional theory (DFT) and beyond. Electronic structure estimations reveal that bulk TiOS is metal whereas the 2D-TiOS possesses a band gap of ∼4.5 eV within GW approximation, which is higher than the band gap of 2D-InOF and 2D transition metal dichalcogenides. The computed phonon dispersion curves show that the 2D-TiOS is dynamically stable. The 2D-TiOS has a very high absorption coefficient in the 0–50 eV. Third-order elastic constants (TOECs) of this 2D-TiOS are achieved using DFT and within the adiabatic-connection fluctuation–dissipation theorem in the random phase approximation. Surprisingly, we find a band overlap, indicating that TiOS/TiOS bilayer is a metal. If the incident light frequency surpasses the plasma frequency (60.00 eV), and then the bilayer turns out to be transparent. Our findings suggest that this 2D sheet is a promising alternative for nanotechnology and optoelectronic devices.

Planar peristrophic multiplexing metasurfaces

As a promising counterpart of two-dimensional metamaterials, metasurfaces enable to arbitrarily control the wavefront of light at subwavelength scale and hold promise for planar holography and applicable multiplexing devices. Nevertheless, the degrees of freedom (DoF) to orthogonally multiplex data have been almost exhausted. Compared with state-of-the-art methods that extensively employ the orthogonal basis such as wavelength, polarization or orbital angular momentum, we propose an unprecedented method of peristrophic multiplexing by combining the spatial frequency orthogonality with the subwavelength detour phase principle. The orthogonal relationship between the spatial frequency of incident light and the locally shifted building blocks of metasurfaces can be regarded as an additional DoF. We experimentally demonstrate the viability of the multiplexed holograms. Moreover, this newly-explored orthogonality is compatible with conventional DoFs. Our findings will contribute to the development of multiplexing metasurfaces and provide a novel solution to nanophotonics, such as large-capacity chip-scale devices and highly integrated communication.

Anapole states and scattering deflection effects in anisotropic van der Waals nanoparticles

Transition metal dichalcogenides (TMDCs), belonging to the class of van der Waals materials, are promising materials for optoelectronics and photonics. In particular, their giant optical anisotropy may enable important optical effects when employed in nanostructures with finite thickness. In this paper, we theoretically and numerically study light scattering behavior from anisotropic MoS2 nanocylinders, and highlight its distinct features advantageous over the response of conventional silicon particles of the same shape. We establish two remarkable phenomena, appearing in the same MoS2 particle with optimized geometry. The first one is a pure magnetic dipole scattering associated with the excitation of the electric-dipole anapole states. Previously reported in core-shell hybrid (metal/dielectric) systems only, it is now demonstrated in an all-dielectric particle. The second phenomenon is the super-deflection in the far field: the maximum scattering may occur over a wide range of directions, including forward-, backward- and side-scattering depending on the mutual orientation of the MoS2 nanocylinder and the incident wave. In contrast to the well-known Kerker and anti-Kerker effects, which appear in nanoparticles at different frequencies, the super-deflection can be achieved by rotating the particle at a constant frequency of incident light. Our results facilitate the development of functional optical devices incorporating nanostructured anisotropic TMDCs and may encourage further research in meta-optics based on highly anisotropic materials.

Operando Raman Spectroscopy of Phase Changes in Nanocrystalline Metal Oxide Lithium-Ion Battery Electrodes

As the demands for clean electricity, transport and highly functional portable electronics grow faster than ever, energy storage remains the main roadblock to progression. Electrochemical devices such as lithium-ion batteries (LIBs), have been the source of most success in overcoming this roadblock. The primary issue with these devices is lifetime decay due primarily to the degradation of the electrodes within the battery. Nanocrystalline materials are often chosen,1 which enhance battery performance by reducing ion diffusion lengths and thus improving rate capabilities. However, structural changes prove difficult to monitor due to their dimensions. The electrochemical processes which cause these changes are also difficult to probe because of their metastability and lifetimes, which can be of nanosecond to sub nanosecond time domains.2 Consequently, the development of methods to capture these processes proves challenging, requiring state-of-the-art techniques. Our work demonstrates that the processes which lead to electrode degradation can in fact be captured by using novel cell designs that provide the ability to adapt analytical techniques to probe battery systems in real time.Raman spectroscopy is particularly useful for multi-layered materials such as the porous metal oxides often used in battery electrodes.3 Information can be revealed on crystal structure, electronic structure, lattice vibrations and flake thickness of layered materials, and can be used to probe the strain, stability, charge transfer, stoichiometry, and stacking order.4 The correlation between the capacity of intercalation in an electrode to the degree of disorder in the material can also be determined.5 Such analysis can be performed during cycling, once the cell is modified to enable light penetration. A pathway is usually provided in the form of an optical window, allowing measurements to be obtained non-destructively in real-time.6 The window material must be transparent to the frequency of incident light chosen for measurements.7 These constitute spectroelectrochemical cells, providing the ability to perform electrochemical and optical measurements simultaneously.Here, we demonstrate a non-destructive approach to monitoring battery degradation in operando. Access for Raman spectroscopy during cycling is provided by a novel cell design. Sapphire is employed as window material, transparent to the 532 nm laser beam used for our Raman measurements. We describe the process applied to a lithium-ion battery based on a metal oxide inverse opals8,9 where the interconnected order porous structure is known to facilitate stable and long term cycling in the absence of binders and conductive additives11-17. However, the same methodology can be extended to any electrode materials with Raman active phase changes at the electrode-electrolyte interface.10 This work provides information on structural and phase changes to the electrode which are compared to microscopy and electrochemical data. References 1 C. Zhu, R. E. Usiskin, Y. Yu, and J. Maier, Science 358, eaao2808 (2017). 2 O. Pecher, J. Carretero-González, K. J. Griffith, and C. P. Grey, Chemistry of Materials 29, 213 (2017). 3 S. Fang, D. Bresser, and S. Passerini, Advanced Energy Materials 10, 1902485 (2020). 4 J.-B. Wu, M.-L. Lin, X. Cong, H.-N. Liu, and P.-H. Tan, Chemical Society Reviews 47, 1822 (2018). 5 K. Kirshenbaum, D. Bock, C.-Y. Lee, Z. Zhong, K. Takeuchi, A. Marschilok, and E. Takeuchi, Science 347, 149 (2015). 6 E. Armstrong, D. McNulty, H. Geaney, and C. O’Dwyer, ACS Applied Materials & Interfaces 7, 27006 (2015). 7 L. Mai, Y. Dong, L. Xu, and C. Han, Nano Letters 10, 4273 (2010). 8 A. Lonergan, D. McNulty, and C. O'Dwyer, Journal of Applied Physics 124, 095106 (2018). 9 J. Yu, J. Lei, L. Wang, J. Zhang, and Y. Liu, Journal of Alloys and Compounds 769, 740 (2018). 10 C. Julien and A. Mauger, AIMS Materials Science 5, 650 (2018). 11 S. O'Hanon, D. McNulty, R. Tian, J. Coleman, and C. O'Dwyer, J. Electrochem. Soc. 167, 140532 (2020). 12 D. McNulty, H. Geaney, Q. Ramasse, and C. O'Dwyer, 2005073 (2020). 13 D. McNulty, H. Geaney, D. Buckley, and C. O'Dwyer, Nano Energy 43, 11 (2018). 14 D. McNulty, E. Carroll, and C. O'Dwyer, Adv. Energy Mater. 7, 1602291 (2017). 15 D. McNulty, A. Lonergan, S. O'Hanlon, and C. O'Dwyer, Solid State Ionics 314, 195 (2018). 16 S. O'Hanlon, D. McNulty, and C. O'Dwyer, J. Electrochem. Soc. 164, D111 (2017). 17 C. O'Dwyer, Adv. Mater. 28, 5681 (2016).

Feedback-based wavefront shaping for weak light with lock-in beat frequency detection.

Feedback-based wavefront shaping is a promising and versatile technique for enhancing the contrast of a target signal through highly scattering media. However, this technique can fail for low optical signals such as fluorescence and Raman signals or in a reflection setup because the trend in weak feedback signals can be easily overwhelmed by noise. To address this challenge, we develop a technique based on a single acousto-optic deflector (AOD) to create a signal with a selected beat frequency from optical signals that can serve as feedback, in which the phase distribution of various radio frequency components of the driving signal for the AOD is optimized for wavefront shaping. By shifting incident light frequency with the AOD, the feedback signal at a selected beat frequency can be measured with a high signal-to-noise ratio (SNR) by a lock-in amplifier, thus enabling the enhancement of weak target signals through highly scattering media. It is found that the method of lock-in beat frequency detection can significantly improve fluorescence imaging and Raman spectral measurements in a reflection setup, and thus could be potentially used for in vivo measurements.

Imbert–Fedorov shift at black phosphorus-coated surfaces

In this work, the Imbert–Fedorov (IF) shift is systematically investigated when a light beam is incident on black phosphorus. Using the angular spectrum theory, we obtain the analytical expressions of IF shifts for a p-polarized and s-polarized beam. Based on the theoretical analysis, numerical calculations are performed. The results indicate that the IF shifts depend on the incident angle, polarization and frequency of incident light, as well as the optical axis angle and electron concentration of black phosphorus. These characteristics make it possible to accurately measure the physical parameters of two-dimensional atomic materials based on IF shifts.

Brillouin frequency shift error estimation formula for distributed optical fiber sensing technology based on Brillouin scattering.

In this work, the problems in the existing Brillouin frequency shift (BFS) error estimation formulas for distributed optical fiber sensing technology based on Brillouin scattering are discussed. Based on the analysis, a new, to the best of our knowledge, BFS error estimation formula is proposed. To validate the proposed formula, a large number of Brillouin spectra with different frequency sweep spans, signal-to-noise ratios, linewidths, and frequency steps are numerically generated, and at the same time, Brillouin spectra with different values of incident light pulse widths and frequency sweep spans are measured with a Brillouin optical time domain reflectometer. Based on those Brillouin spectra, the errors of the proposed formula and existing formulas are systematically compared. The results reveal that the proposed formula generally has a higher accuracy than the existing typical formulas, especially when the frequency sweep span or incident light pulse width is large. Therefore, it has a much wider application range.

Electronic, Optical, and Elastic Properties of CaFI Monolayer and Acoustic Phonon Dispersion at Hypersonic Frequencies Using Density Functional Theory and beyond with Random Phase Approximation and Bethe-Salpeter Equation.

The extraordinary properties of graphene have motivated us to investigate a novel 2D compound. In this framework, we study the structural, vibrational, electronic, optical, and elastic properties of a new two-dimensional CaFI monolayer, using DFT, GW, RPA, and BSE methodologies. The phonon dispersion curve of the CaFI monolayer exhibited no unstable phonon modes, confirming that this 2D sheet is dynamically stable. Our GW calculations show that the indirect bandgap energy value of CaFI is 6.52 eV. Interestingly, the bandgap rapidly decreased by improving the electric field value. Our BSE computations indicate that this monolayer becomes translucent when the incident light frequency exceeds the plasma frequency (6.50 eV). Also, we have computed the second and third elastic constants of CaFI by combining the DFT and RPA approaches with the homogeneous deformation method. Additionally, the longitudinal acoustic phonon dispersion of CaFI was studied. We have determined that the longitudinal acoustic wave velocity in our sheet is higher than the LA wave velocity of germanium measured using Brillouin or ultrasonic techniques.

Two-dimensional phonon polaritons in multilayers of hexagonal boron nitride from a macroscopic phonon model

Phonon polaritons (PHPs) in freestanding and supported multilayers of hexagonal boron nitride are systematically studied using a macroscopic optical-phonon model. The PHP properties such as confinement, group velocity, propagation quality factor (PQF), and wavelength scaling are studied. Owing to high-frequency screening, there is an upper frequency limit making the two-dimensional (2D) PHPs have a frequency band and also a maximum PQF occurs near the center frequency. The substrate’s dielectric response should be included to accurately calculate the PHP properties. While the simple electrostatic approximation (ESA) is valid for PHPs with frequencies ω above ω0 (e.g., ω>1.03ω0 for the 30-layers; ω0 is the Γ point optical-phonon frequency), it fails to describe the PHP properties near ω0 and the effect of retardation should be included for a proper description. The PHP wavelength vs layer thickness near ω0 deviates significantly from a linear scaling law given by the ESA due to strong coupling of photons and longitudinal optical phonons. The calculated PHP dispersion and scaling are compared with experimental data of a number of spectroscopic studies and found to be in good agreement for most of the results. While the frequency of incident light should be near the center frequency to maximize the PQF, the PHP wavelength, confinement, and propagation length can be engineered by varying the multilayer thickness and its dielectric environment.