We propose a theoretical model of reflective modulators for seeded dense wavelength-division multiplexing (DWDM) system based on amplified spontaneous emission light. A travelling-wave amplifier is modified to take into account the finite front-facet reflectivity. The net gain and phase shift are updated at every round trip cavity have complex injected field. With proposed model, we calculate side-mode suppression ratio, gain, relative intensity noise as function injection power, wavelength...

Abundant available spectral resources in terahertz (THz) bands enables opportunities to develop next-generation mobile communications. However, devices with large operating bandwidths are required exploit the benefits offered by THz band, which significantly increases cost and complexity of implementation. In addition, frequencies experience a relatively propagation loss, inevitably reduces network coverage; thus, numerous antenna sites provide reliable services. Therefore, implementing...

We investigate the feasibility of pulse amplitude modulation-N (PAM-N) signal transmission over a photonics-based cost-effective THz wireless link. A direct detection-based link was established by using commercialized optical and electrical components designed for WR 3.4 frequency band (220-330 GHz). At transmitter, uni-traveling carrier photodiode (UTC-PD) used as photomixer. The maximum output power UTC-PD ~47 μW when it supplied with +17 dBm power. receiver, Schottky barrier diode...

We propose an indoor network with a sub-terahertz- band wireless link for 6G applications. In our proposed network, optical hub unit (OHU) that controls the entire system is optically linked to THz remote nodes (RNs) over distribution fibers. The RNs communicate user equipment through sub-THz link. function of provide interface between and For downlink transmission, photonics-based sub-THz-band signal generation method adopted take advantage broadband characteristics components. An...

Coherent terahertz (THz) wireless communication using silicon photonics technology provides critical solutions for achieving high-capacity transmission beyond 5G and 6G networks seamless connectivity with fiber-based backbone networks. However, high-quality THz signal generation noise-robust detection remain challenging owing to the presence of inter-channel crosstalk additive noise in environments. Here, we report coherent a photonic integrated circuit that includes dual-parallel...

Anion exchange membrane water electrolyzer (AEM electrolyzer) is an advanced technology for converting electrical energy into hydrogen with high efficiency and low cost. However, its advantages are diminished by...

Correction for ‘Yolk–shell structured microspheres consisting of CoO/CoP hetero-interfaced nanocomposites as highly active hydrogen evolution reaction electrocatalysts AEM electrolyzer stacks’ by In Tae Kim et al. , J. Mater. Chem. A 2025, https://doi.org/10.1039/D4TA07211A.

Large bandwidths at terahertz (THz) frequencies higher than 100 GHz have been garnering significant attention as key enablers for future wireless networks to provide data rates in the range of terabits per second, which is approximately one hundred times transmission rate millimeter systems. To fully utilize merits THz frequencies, devices with large operating are highly desired. From this perspective, promising choices photonic developed fiber-optic communications, commonly used since early...

All-fiber 6-mode multiplexer composed of two consecutive LP11-mode selective couplers (MSC), LP21-MSCs and an LP02-MSC is fully characterized by wavelength-swept interferometer technique. The MSCs are fabricated polished-type fiber coupling LP01 mode a single into higher-order few fiber. A pair the multiplexers has minimum dependent loss 4 dB high group selectivity over 15 dB. Mode division multiplexed transmission enabled all-fiber demonstrated spans 117 km employing in-line multi-mode...

The telecommunication society is paving the way toward ultra-high frequency regions, including millimeter wave (mmWave) and sub-terahertz (sub-THz) bands. Such high-frequency electromagnetic waves induce a variety of physical constraints when they are used in wireless communications. Inevitably, fiber-optic network deeply embedded mobile to resolve such challenges. In particular, radio-over-fiber (RoF)-based distributed antenna system (DAS) can enhance accessibility next-generation networks....

We propose a DSP scheme with soft-output maximum likelihood sequence equalizer (sMLSE) and low-overhead (8.51%) low density parity check (LDPC) code for C-band PAM-4 transmission. In order to apply LDPC in conjunction MLSE, the conventional hard-output MLSE is modified have value by using Max-log BCJR algorithm. The feasibility of this approach experimentally investigated 56 Gb/s system. investigate advantages proposed scheme, we compare performance sMLSE-LDPC that MLSE-RS code. Relatively,...

We experimentally demonstrate the use of silicon photonics circuit (SPC) in simple and cost-effective photonics-aided Terahertz (THz) wireless transmission system. perform theoretical investigation (with experimental confirmation) to understand that system performance is more sensitive free space path loss (FSPL) at THz link than SPC's insertion loss. The SPC, we design fabricate, combines two incident optical carriers different wavelengths modulates one with data transfer, consequently...

We propose an automatic wavelength control method using Rayleigh backscattering in a feeder fiber for tunable lasers employed wavelength-division multiplexing passive optical network. demonstrate two realization methods, maximizing backscattered power and the second harmonic component with modulation. analyze their limiting factors impacts on system performance. use VCSEL as low-cost light source.

We demonstrate and characterize 800 Gb/s capacity WDM-PON with an ASE injection seeding. Required total seed power at central office to feeder fiber is 16 dBm for 20 km upstream transmission of 80 channels. investigate the maximum length according The limited 39.7 by intra-channel crosstalk induced Rayleigh back-scattering, provided that dispersion compensated. Also, we allowable differential path evaluate flexibility system.

We demonstrate a 400-Gb/s ASE injection seeded WDM-PON. A cost-effective SOA-REAM and FEC were utilized to enhance the BER performance. required total seed power at OLT was 8.6 dBm with 2nd generation FEC.

Sub-terahertz (THz)-band communication system has drawn much attention as a promising technology to provide future-proof high data rate services. In photonics-based sub-THz system, the generation of THz wave using free running lasers enables us make simple, cost effective and frequency tunable implementation. On other hand, commercially available have relatively broader linewidth large carrier offset (CFO). To mitigate performance degradations due phase noise CFO, recovery digital signal...

We demonstrate a 25 GHz-channel-spaced DWDM-PON based on ASE injection seeding. A 60 km transmission at 1.25 Gb/s per channel is available with 2nd generation FEC. The major limiting factor the optical back reflection induced penalty. Thus high gain reflective modulator and/or relocation of seed light increase length. demonstrated 90 relocated to remote node.

We demonstrate an automatic wavelength control method using Rayleigh backscattering and modulation for tunable lasers in a WDM-PON. By measuring the spectrum of backscattered light, we identified tracked allocated wavelength.

We present a cost-effective photonics-based THz wireless delivery system using directly modulated distributed feedback laser diode (DFB-LD). A DFB-LD with non-return to zero (NRZ) modulation up 25 Gbps and uni-traveling-carrier photodiode (UTC-PD) horn antenna is employed transmit wave into free space in the signal transmitter. Schottky barrier (SBD) used detect from at receiver. To achieve best bit error rate performance, we varied optimal carrier frequency system. After optimization, rates...

Flexible polymer waveguide with a Bragg reflection grating is incorporated to form an external cavity laser wide tuning range, and it evaluated as tunable light source for wavelength division multiplexing optical communication systems. The highly elastic property of materials makes them suitable producing reflector controlled by imposed strain. flexible installed on compact moving stage 6 connected piezoelectric motor. By applying total strain 60680 με (6.07%), 82 nm achieved side-mode...

In this letter, a soft-decision Viterbi algorithm (SOVA) combined with low-density parity check is investigated to achieve high chromatic dispersion tolerance and alleviate the optical signal-to-noise ratio (OSNR) requirement in pulse amplitude modulation 4-level (PAM-4) systems. To reduce complexity increase over maximum likelihood sequence equalizer, we propose non-binary SOVA combining conventional hard decision VA. low complexity, only one competing path state time index used update...

We designed and realized real-time pulse amplitude modulation-4 (PAM-4) digital signal processing (DSP) including forward error correction (FEC) for a C-band inter-datacenter network. The PAM-4 DSP is intended to compensate chromatic dispersion provide tolerance. A decision feedback equalizer (DFE) maximum likelihood sequence (MLSE) were employed the compensation. low-density parity check (LDPC) code was used increase coding gain. soft-decision Viterbi algorithm (SOVA) adopted probabilistic...