Laser shaping and optical power limiting of pulsed Laguerre–Gaussian laser beams of high-order radial modes in fullerene C60

We study the strong nonlinear optical dynamics of nanosecond pulsed Laguerre–Gaussian laser beams of high-order radial modes with zero orbital angular momentum propagating in the fullerene C60molecular medium. It is found that the spatiotemporal profile of the incident pulsed Laguerre–Gaussian laser beam is strongly reshaped during its propagation in the C60molecular medium. The centrosymmetric temporal profile of the incident pulse gradually evolves into a noncentrosymmetric meniscus shape, and the on-axis pulse duration is clearly depressed. Furthermore, the field intensity is distinctly attenuated due to the field-intensity-dependent reverse saturable absorption, and clear optical power limiting behavior is observed for different orders of the input pulsed Laguerre–Gaussian laser beams before the takeover of the saturation effect;the lower the order of the Laguerre–Gaussian beam, the lower the energy transmittance.

Instantaneous frequency measurement using two parallel I/Q modulators based on optical power monitoring

A scheme for instantaneous frequency measurement(IFM)using two parallel I/Q modulators based on optical power monitoring is proposed.The amplitude comparison function(ACF)can be constructed to establish the relationship between the frequency of radio frequency(RF)signal and the power ratio of two optical signals output by two I/Q modulators.The frequency of RF signal can be derived by measuring the optical power of the optical signals output by two I/Q modulators.The measurement range and measurement error can be adjusted by controlling the delay amount of the electrical delay line.The feasibility of the scheme is verified,and the corresponding measurement range and measurement error of the system under different delay amounts of the electrical delay line are given.Compared with previous IFM schemes,the structure of this scheme is simple.Polarization devices,a photodetector and an electrical power meter are not used,which reduces the impact of the environmental disturbance on the system and the cost of the system.In simulation,the measurement range can reach 0 GHz-24.5 GHz by adjusting the delay amount of the electrical delay lineτ=20 ps.The measurement error of the scheme is better at low frequency,and the measurement error of low frequency 0 GHz-9.6 GHz can reach-0.1 GHz to+0.05 GHz.

Optical engineering of infrared PbS CQD photovoltaic cells for wireless optical power transfer systems

Infrared photovoltaic cells(IRPCs)have attracted considerable attention for potential applications in wireless optical power transfer(WOPT)systems.As an efcient fber-integrated WOPT system typically uses a 1550 nm laser beam,it is essential to tune the peak conversion efciency of IRPCs to this wavelength.However,IRPCs based on lead sulfde(PbS)colloidal quantum dots(CQDs)with an excitonic peak of 1550 nm exhibit low short circuit current(Jsc)due to insufcient absorption under monochromatic light illumination.Here,we propose comprehensive optical engineering to optimize the device structure of IRPCs based on PbS CQDs,for 1550 nm WOPT systems.The absorption by the device is enhanced by improving the transmittance of tin-doped indium oxide(ITO)in the infrared region and by utilizing the optical resonance efect in the device.Therefore,the optimized device exhibited a high short circuit current density of 37.65 mA/cm^(2)under 1 sun(AM 1.5G)solar illumination and 11.91 mA/cm^(2)under 1550 nm illumination 17.3 mW/cm^(2).Furthermore,the champion device achieved a record high power conversion efciency(PCE)of 7.17%under 1 sun illumination and 10.29%under 1550 nm illumination.The PbS CQDs IRPCs under 1550 nm illumination can even light up a liquid crystal display(LCD),demonstrating application prospects in the future.

Study on K^+-Na^+ Ion-Exchange Multimode Interference Optical Power Splitter

The principle of weak-confined Multimode Interference is studied, and then a 1×8 K+-Na+ ion-exchange multimode interference optical power splitter is designed and fabricated.

Compact Hybrid Subsystem of 16 Channel Optical Demultiplexer, 2x2 Switches, Optical Power Monitors and Control Circuit

A compact hybrid subsystem of 16channel optical demultiplexer, 2x2 switches, optical power monitors and control circuit board is developed. The subsystem is able to add or drop arbitrary optical channels and monitor the optical power level by software commands. The size of the subsystem is 170x200x30(mm).

MMI Double-Wavelength Optical Power Splitter

An MMI double-wavelength optical power splitter for both 1.55μm and 1.3μm is presented in this paper. Analysis shows that it can divide power equally for both 1.55μ m and 1.3μm.

Quantum cascade lasers grown by MOCVD

Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,medical diagnosis,and defense applications.Metalorganic chemical vapor deposition(MOCVD)is an important technology for growing high quality semiconductor materials,and has achieved great success in the semiconductor industry due to its advantages of high efficiency,short maintenance cycles,and high stability and repeatability.The utilization of MOCVD for the growth of QCL materials holds a significant meaning for promoting the large batch production and industrial application of QCL devices.This review summarizes the recent progress of QCLs grown by MOCVD.Material quality and the structure design together determine the device performance.Research progress on the performance improvement of MOCVD-grown QCLs based on the optimization of material quality and active region structure are mainly reviewed.

A comprehensive review of optical wireless power transfer technology

Ground-breaking optical wireless power transfer(OWPT)techniques have gained significant attention from both academia and industry in recent decades.Powering remote systems through laser diodes(LDs)to either operate devices or recharge batteries offers several benefits.Remote LDs can remove the burden of carrying extra batteries and can reduce mission time by removing battery swap-time and charging.Apart from its appealing benefits,laser power transfer(LPT)is still a challenging task due to its low transfer efficiency.In this paper,we discuss the necessity and feasibility of OWPT and discuss several projects,working principle,system design,and components.In addition,we show that OWPT is an essential element to supply power to Internet-of-Things(IoT)terminals.We also highlight the impacts of dynamic OWPT.We outline several OWPT techniques including optical beamforming,distributed laser charging(DLC),adaptive-DLC(ADLC),simultaneous lightwave information and power transfer(SLIPT),Thing-to-Thing(T2T)OWPT,and high intensity laser power beaming(HILPB).We also deal with laser selection,hazard analysis,and received photovoltaic(PV)cell selection for OWPT systems.Finally,we discuss a range of open challenges and counter measures.We believe that this review will be helpful in integrating research and eliminating technical uncertainties,thereby promoting progress and innovation in the development of OWPT technologies.

Characterization of Blue-Green Light Non-Line-of-Sight Transmission in Seawater

The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve communication in non-line-of-sight (NLOS) transmission mode. Compared to line-of-sight (LOS) transmission, NLOS transmission does not require alignment and can be adapted to various underwater environments. The scattering coefficients of seawater at different depths are different, which makes the scattering of light in different depths of seawater different. In this paper, the received optical power and bit error rate (BER) of the photodetector (PD) were calculated when the scattering coefficients of blue-green light in seawater vary from large to small with increasing depth for NLOS transmission. The results show that blue-green light in different depths of seawater in the same way NLOS communication at the same distance, the received optical power and BER at the receiver are different, and the received optical power of green light is greater than that of blue light. Increasing the forward scattering coverage of the laser will suppress the received optical power of the PD, so when performing NLOS communication, appropriate trade-offs should be made between the forward scattering coverage of the laser and the received optical power.

Optimization of optical wireless power transfer using near-infrared laser diodes

We experimentally demonstrated optical wireless power transfer(OWPT)using a near-infrared laser diode(LD)as the optical power transmitter.We considered a photovoltaic(PV)cell and a photodiode(PD)as the optical power receivers.We investigated the characteristics of the LD,PD,and PV cell in order to determine the optimum operating condition from the viewpoint of transfer efficiency.We also experimentally demonstrated a whole system optimization process to maximize the DC-to-DC transfer efficiency of the OWPT.Our experimental results showed that the optimization process can improve the OWPT efficiency by up to 48%.

Prediction-based dynamic routing intelligent algorithm in power optical communication network

New energy power generation equipment has the characteristics of diurnal, perturbative, seasonal, and periodic power generation, which makes new power optical communication network(POCN) more dynamic and changeable. This is directly reflected in the dynamics of the link risk and service importance of the POCN. In this paper, aiming at the problem of the dynamic importance of service in POCN, and the resulting power optical communication network reliability decline problem, a new energy POCN dynamic routing intelligence algorithm based on service importance prediction is proposed. Based on the short-term power generation of new energy power station, the importance of each service and the risk degree of each link are predicted. Link weights are dynamically adjusted, and k-shortest path(KSP) algorithm is used to calculate route results. When network resources are insufficient, low-importance services can give way to prevent a large number of high-importance services from being blocked. Simulation results show that compared with the traditional KSP algorithm, the prediction-based dynamic routing intelligent(P-DRI) algorithm can reduce the service blocking probability by 55.59%, and reduce the average importance of blocking services by 44.77% at the cost of about 6.17% of the calculation delay.

Numerical Simulation for FWM Power Evaluation in Optical Fiber Transmission Systems

In order to realize reliable and fast simulation of FWM power evaluation, USSD (Uniform Step-Size Distribution) method is modified and its corresponding simulation results of FWM efficiency and computational time are presented.

Hybrid optical wavelength demultiplexer and power combiner for TWDM PON

In this paper,we have proposed a hybrid optical wavelength demultiplexer and power combiner for a hybrid timeand wavelength-division multiplexing(TWDM)passive optical network(PON),i.e.,a single passive optical device that functions as a 1×N wavelength demultiplexer for distributing the downstream signal in multiple wavelengths from the optical line terminal(OLT)to the N optical network units(ONUs),and simultaneously as an N×1 power combiner for collecting the upstream signal in the same wavelength from the N ONUs to the OLT.Through a design example of a 32 channel hybrid optical wavelength demultiplexer and power combiner on the silicon-on-insulator platform,our numerical simulation result shows that the insertion loss and adjacent channel crosstalk of the downstream wavelength demultiplexer are as low as 4.6 and-16.3 dB,respectively,while the insertion loss and channel non-uniformity of the upstream power combiner can reach 3.5 and 2.1 dB,respectively.The proposed structure can readily be extended to other material platforms such as the silica-based planar lightwave circuit.Its fabrication process is fully compatible with standard clean-room technologies such as photolithography and etching,without any complicated and/or costly approach involved.

Co‑packaged optics(CPO):status,challenges,and solutions

Due to the rise of 5G,IoT,AI,and high-performance computing applications,datacenter trafc has grown at a compound annual growth rate of nearly 30%.Furthermore,nearly three-fourths of the datacenter trafc resides within datacenters.The conventional pluggable optics increases at a much slower rate than that of datacenter trafc.The gap between application requirements and the capability of conventional pluggable optics keeps increasing,a trend that is unsustainable.Copackaged optics(CPO)is a disruptive approach to increasing the interconnecting bandwidth density and energy efciency by dramatically shortening the electrical link length through advanced packaging and co-optimization of electronics and photonics.CPO is widely regarded as a promising solution for future datacenter interconnections,and silicon platform is the most promising platform for large-scale integration.Leading international companies(e.g.,Intel,Broadcom and IBM)have heavily investigated in CPO technology,an inter-disciplinary research feld that involves photonic devices,integrated circuits design,packaging,photonic device modeling,electronic-photonic co-simulation,applications,and standardization.This review aims to provide the readers a comprehensive overview of the state-of-the-art progress of CPO in silicon platform,identify the key challenges,and point out the potential solutions,hoping to encourage collaboration between diferent research felds to accelerate the development of CPO technology.