All-optical Phase Modulation Research Articles

Effect of Sn nanoparticles on the optical properties of PEDOT:PSS thin films

Introduction: In this study, we focus on enhancing the optical properties of PEDOT:PSS thin films by incorporating pure Sn nanoparticles (NPs) synthesized using the ultrasonic ablation technique. The objective is to investigate the impact of Sn concentration on the optical characteristics of the films, with a specific emphasis on applications in organic solar cells.Methods: We systematically varied the concentrations of Sn in PEDOT:PSS thin films and characterized their optical properties. The index of refraction (n) and extinction coefficient (k) were precisely determined by analyzing the transmission and reflection spectra of the films. Additionally, Sellmeier’s dispersal model was employed to elucidate the obtained results of n, and dispersive factors were calculated and interpreted.Results: The incorporation of Sn nanoparticles led to improvements in the energy bandgap (Eg) values of PEDOT:PSS films. Notably, as the concentration of Sn increased, the n values decreased, indicating enhanced suitability for organic solar cell applications. The study also unveiled a decrease in the dielectric constant of PEDOT:PSS/Sn films with increasing Sn content, resulting in improved transmittance velocity and enhanced efficacy of microelectronic devices. This, in turn, promotes the development of large-frequency and large-velocity stretchy circuit boards.Discussion: The comprehensive assessment of optical and dielectric parameters, including complex dielectric constant, complex optical conductance, and nonlinear optical constants, provides valuable insights into the potential applications of PEDOT:PSS/Sn films. The larger nonlinear optical constants observed in the present films suggest their suitability for diverse applications such as all-optical switching, limiting, phase modulation, and frequency conversion. Overall, our findings highlight the promising potential of Sn-incorporated PEDOT:PSS thin films in advancing the field of optoelectronics and microelectronics.

Integrated Fabry–Perot interferometer based on Er/Yb co-doped fiber for all-optical phase modulation

Integrated Fabry–Perot interferometer based on Er/Yb co-doped fiber for all-optical phase modulation

Ultra-sensitive all-optical phase modulation based on a fiber optic interferometer combined with Ti3C2Tx MXene-incorporated PDMS.

This study proposes an all-optical phase modulator based on a compact fiber optic interferometer combined with Ti3C2Tx MXene-incorporated PDMS. Due to the high photothermal conversion efficiency of MXene and the high thermo-optic coefficient of PDMS, changes in pump power can be effectively converted into refractive index (RI) variations in the PDMS. Then, by employing a fiber optic interferometer with a high RI response, ultra-sensitive all-optical phase modulation can be realized. The experimental results demonstrate that the resonant wavelength shift of the modulator with MXene-incorporated PDMS is 126 times higher than that of a modulator with single MXene deposition. Also, a maximum wavelength sensitivity of 14.57 nm/mW is achieved (equivalent to a phase sensitivity of 0.33π/mW); this excellent modulation performance is a great improvement on that of a previously reported fiber-based all-optical phase modulator. Furthermore, PDMS is also employed as a packaging layer to strengthen the device structure and restrict the heat in an enclosed space, which improves the heat utilization efficiency. The proposed device shows great potential in optical communication, optical filtering, sensing, and modulation applications.

Archimedean spiral waveguide as efficient all-optical phase modulator for space laser beam pointing

Silicon nanophotonics is contributing to the development of devices with small dimensions and low energy consumption. In optical systems for space applications, whether in large or small satellites, such as CubeSat, the demand for photonic devices has been a necessity, mainly in the communication subsystem, due to limitations in the conventional optical beam pointing subsystems. Silicon nanophotonics can be a solution in this case as it allows for the construction of an optical beam pointing system without moving parts, such as optical phased array antennas, in which the component responsible for the pointing functionality is the optical phase modulator. With this objective, we propose an efficient non-resonant all-optical modulator based on an Archimedean spiral waveguide topology by means of the indirect thermo-optical effect. Computational results are presented and discussed.

Mid-infrared all-optical modulators based on an acetylene-filled hollow-core fiber

We report all-optical mid-infrared phase and intensity modulators based on the photo-thermal effect in an acetylene-filled anti-resonant hollow-core fiber. Optical absorption of the control beam promotes the gas molecules to a higher energy level, which induces localized heating through non-radiative relaxation and modulates the refractive index of the gas material and hence the accumulated phase of the signal beam propagating through the hollow-core fiber. By modulating the intensity of the control beam, the phase of the signal beam is modulated accordingly. By use of a 1.53 µm near-infrared control beam, all-optical phase modulation up to 2.2π rad is experimentally demonstrated at the signal wavelength of 3.35 µm. With the phase modulator placed in one arm of a Mach-Zehnder interferometer, intensity modulation with on-off ratio of 25 dB is achieved. The gas-filled hollow-core-fiber modulators could operate over an ultra-broad wavelength band from near- to mid-infrared and have promising application in mid-infrared photonic systems.

Graphdiyne-deposited microfiber structure all-optical modulator at the telecommunication band.

All-optical modulator is a crucial device in next generation of all-optical communications, interconnects, and signal processing. Here, we demonstrate an all-optical phase modulator with graphdiyne (GDY)-deposited microfiber structure. The phase shift of the signal light can be readily controlled by pump light by thermo-optic effect. This all-optical modulator can achieve a phase shift slope of 0.0296 π·mW-1 and a rising time of 5.48 ms at 25 Hz (3 ms, 50 Hz). Modes distributions in GDY-deposited microfiber at different wavelength are numerical analyzed and the normalized phase conversion efficiency of GDY are calculated. The results show that GDY has a considerable normalized phase conversion efficiency of 0.1644 π·mW-1·mm-1, which is higher than that of graphene, MXene and WS2 based all-optical modulators. This work proves the potential of GDY in all-optical modulator device at telecommunication band and provides a support to all-optical signal processing systems.

Synchronization and Phase Shaping of Single Photons with High-Efficiency Quantum MemorySupported by the National Key Research and Development Program of China (Grant No. 2020YFA0309500), the Key-Area Research and Development Program of Guangdong Province (Grant No. 2019B030330001), the Key Project of Science and Technology of Guangzhou (Grant No. 2019050001), and the National Natural Science Foundation of China (Grant Nos. 11822403, 62005082,

Time synchronization and phase shaping of single photons both play fundamental roles in quantum information applications that rely on multi-photon quantum interference. Phase shaping typically requires separate modulators with extra insertion losses. Here, we develop an all-optical built-in phase modulator for single photons using a quantum memory. The fast phase modulation of a single photon in both step and linear manner are verified by observing the efficient quantum-memory-assisted Hong–Ou–Mandel interference between two single photons, where the anti-coalescence effect of bosonic photon pairs is demonstrated. The developed phase modulator may push forward the practical quantum information applications.

Optical Microfiber All-Optical Phase Modulator for Fiber Optic Hydrophone.

In order to meet the needs of phase generated carrier (PGC) demodulation technology for interferometric fiber optic hydrophones, we proposed an optical microfiber all-optical phase modulator (OMAOPM) based on the photo-induced thermal phase shift effect, which can be used as a phase carrier generation component, so as to make the modulation efficiency and working bandwidth of this type of modulator satisfy the requirements of underwater acoustic signal demodulation applications. We analyzed the modulation principle of this modulator and optimized the structural parameters of the optical microfiber (OM) when the waist length and waist diameter of OM are 15 mm and 1.4 μm, respectively. The modulation amplitude of the modulator can reach 1 rad, which can meet the requirements of sensing applications. On this basis, the fiber optical hydrophone PGC-Atan demodulation system was constructed, and the simulated underwater acoustic signal test demodulation research was carried out. Experimental results showed that the system can demodulate underwater acoustic signals below 1 kHz.

Enhancing SiN waveguide optical nonlinearity via hybrid GaS integration

Silicon nitride (SiN) has been demonstrated as an exceptional low-loss platform for integrated photonics, however, its relatively small nonlinear refractive index limits its full potential in applications such as all-optical phase modulation, supercontinuum generation, and frequency combs. Here, we demonstrate that through hybrid integration with wide-bandgap 2D materials such as gallium sulfide (GaS), the nonlinear refractive index of the hybrid waveguide can be greatly increased (by five-fold in our experiment). We fabricate high quality factor SiN/GaS microring resonators, with low two-photon absorption at telecom wavelengths, to demonstrate enhanced all-optical modulation. We show that the hybrid platform is suitable for assessing the nonlinear properties of 2D materials, and we have used it to quantify, for the first time, the nonlinear refractive index (n 2) of GaS. For GaS, n 2 = , which is ten times larger than that of SiN.

Wavelength conversion using fiber cross-phase modulation driven by two pump waves.

Wavelength conversion using all-optical phase modulation in a fiber driven by two pump waves is investigated. The operation features are analyzed using an all-optical phase modulation model with two parallel-/cross-polarized pump waves to generate a phase-preserving copy of the optical signal at an exact frequency up-/down-shifted by the two-pump detuning. The conversion efficiency is experimentally verified using a 300-m highly-nonlinear fiber. The results agree well with a theoretical prediction. The conversion bandwidth over 4 THz is achieved and error-free wavelength conversion for a 32-GBd polarization-division multiplexed 16QAM signal is demonstrated. The technique's applicability to a large-capacity wavelength-division multiplexed signals is also discussed.

Thermal stress-induced all-optical modulation in MXene-coated polarization maintaining fiber

All-optical modulation has attracted increasing attention in photonics and optoelectronics for its great potential in all-optical communication, interconnects and signal processing. In this paper, an all-optical modulator based on MXene’s strong photo-thermal effect is proposed. The microfiber stereo structure enhances the light–matter interaction length, and the polarization maintaining fiber improves the environmental stability of the modulator. The all-optical modulation was successfully used to realize all-optical phase modulation and intensity modulation. For phase modulation, a free spectral range of 1.3 nm and an extinction ratio of ~20 dB were obtained with excellent stability. For intensity modulation, the rising/falling time was 0.6/0.3 s. This stable and multifunctional all-fiber modulator is intrinsically compatible with the fiber system and has potential application in all-optical information processing.

A bismuthene-based multifunctional all-optical phase and intensity modulator enabled by photothermal effect

Based on the excellent photothermal effect in few-layer bismuthene, an all-optical phase and intensity modulator has been designed and successfully verified with multifunctional properties, including phase shifting, wavelength tuning, intensity modulating and information loading.

All-optical spatial phase modulation in films of dye-doped DNA biopolymer

The deoxyribonucleic acid (DNA) is a new “green” photonic material with promising applications in organic photonics. In this paper we report the results obtained in an experimental study of the spatial phase modulation induced by light in DNA – cetyltrimethyl-ammonium chloride (CTMA) – Disperse Red (DR1) films. Using a pump-probe interferometric method, recently introduced by us, the spatial distribution of the optical phase change, its magnitude and its dependence on the incident pump intensity are determined in the investigated DNA-CTMA-DR1 films. Processes responsible for the light-induced phase modulation in DNA-CTMA-DR1 film are briefly discussed and their contribution to the overall phase modulation is estimated. The results are important for nonlinear photonics in applications based on all-optical spatial light modulation.

Light-addressable liquid crystal polymer dispersed liquid crystal

Scattering-free liquid crystal polymer-dispersed liquid crystal polymer (LCPDLC) films are fabricated by combining a room temperature polymerizable liquid crystal (LC) monomer with a mesogenic photosensitive LC. The morphological and photosensitive properties of the system are analysed with polarized optical microscopy and high resolution scanning and transmission electron microscopy. A two-phase morphology comprised of oriented fibril-like polymeric structures interwoven with nanoscale domains of phase separated LC exists. The nanoscale of the structures enables an absence of scattering which allows imaging through the LCPDLC sample without optical distortion. The use of a mesogenic monomer enables much smaller phase separated domains as compared to non-mesogenic systems. All-optical experiments show that the transmitted intensity, measured through parallel polarizers, can be modulated by the low power density radiation (31 mW/cm2) of a suitable wavelength (532 nm). The reversible and repeatable transmission change is due to the photoinduced trans-cis photoisomerization process. The birefringence variation (0.01) obtained by optically pumping the LCPDLC films allow their use as an all-optical phase modulator.

All-optical Polarization Phase Modulation in Coupled Quantum Dots

We have considered optical nonlinearities of coupled quantum dots theoretically, where an exciton dipole-dipole interaction is mediated between the adjacent large and small quantum dots. For increasing a pump pulse area in resonance with the large quantum dot exciton the induced nonlinear refractive index of the small quantum dot exciton has been obtained. As the exciton dipole-dipole interaction depends on the relative orientation of two exciton dipoles, the optical nonlinearities for the directions parallel and perpendicular to the coupling axis of the two quantum dots are compared. The directional imbalance of optical nonlinearities in coupled quantum dots can be utilized for a polarization phase modulator by controlling a pump pulse area and propagation length.

基于微纳光纤全光相位调制器的PGC解调系统

基于微纳光纤全光相位调制器的PGC解调系统

Linear readout of integrated interferometric biosensors using a periodic wavelength modulation

An all-optical phase modulation method for the linear readout of integrated interferometric biosensors is demonstrated, merging simple intensity detection with the advantages offered by spectral interrogation. The phase modulation is introduced in a simple and cost-effective way by tuning a few nanometers the emission wavelength of commercial laser diodes, taking advantage of their well-known drawback of power–wavelength dependence. The method is applied to the case of a bimodal waveguide (BiMW) interferometric biosensor, fabricated with standard silicon technology and operated at visible wavelengths, rendering a detection limit of 4 × 10 − 7 refractive index units for bulk sensing. The biosensing capabilities of the phase-linearized BiMW device are assessed through the quantitative immunoassay of C-reactive protein, a key protein in inflammatory processes. This method can be applied to any modal interferometer.

OOK-to-QPSK modulation-format conversion based on two gain-transparent SOAs

In this paper, the system scheme of on–off keying (OOK) to quadrature phase-shift keying (QPSK) format conversion is proposed, which is based on two gain-transparent semiconductor optical amplifiers (GT-SOA). GT-SOA is used as a simple all-optical phase modulator, which is no effects of cross gain modulation and four-wave mixing existing in conventional SOA. The assistant light is used to speed up the SOA carrier recovery time. The principles of OOK to QPSK format conversion are expounded. The influences of the assistant light power and signal light power on the conversions are numerically analyzed. The OOK signal can still be exactly converted to the QPSK signal with the power of OOK signal being changed within a certain range.

Amplified all-optical polarization phase modulator assisted by a local surface plasmon in Au-hybrid CdSe quantum dots

We propose an amplified all-optical polarization phase modulator assisted by a local surface plasmon in Au-hybrid CdSe quantum dots. When the local surface plasmon of a spherical Au quantum dot is in resonance with the exciton energy level of a CdSe quantum dot, a significant enhancement of the linear and nonlinear refractive index is found in both the real and imaginary terms via the interaction with the dipole field of the local surface plasmon. Given a gating pulse intensity, an elliptical polarization induced by the phase retardation is described in terms of elliptical and rotational angles. In the case that a larger excitation than the bleaching intensity is applied, the signal light can be amplified due to the presence of gain in the CdSe quantum dot. This enables a longer propagation of the signal light relative to the metal loss, resulting in more feasible polarization modulation.

All-optical phase modulation for integrated interferometric biosensors

We present the theoretical and the experimental implementation of an all-optical phase modulation system in integrated Mach-Zehnder Interferometers to solve the drawbacks related to the periodic nature of the interferometric signal. Sensor phase is tuned by modulating the emission wavelength of low-cost commercial laser diodes by changing their output power. FFT deconvolution of the signal allows for direct phase readout, immune to sensitivity variations and to light intensity fluctuations. This simple phase modulation scheme increases the signal-to-noise ratio of the measurements in one order of magnitude, rendering in a sensor with a detection limit of 1.9·10⁻⁷ RIU. The viability of the all-optical modulation approach is demonstrated with an immunoassay detection as a biosensing proof of concept.