Ion-Implanted Erbium in X-cut Thin-film Lithium Niobate: Luminescence and Low-Temperature Response

Authors: Daniel Blight, Mason Adshead, Alessandro Prencipe, Mayam Sanaee, Katia Gallo, Richard J Curry

Published: November 6, 2025

This study presents a method for deterministic Er3+ doping of x-cut TFLN
using focused ion beam (FIB) implantation with sub-100 nm spatial precision,
enabling seamless integration of active rare-earth ions into this
technologically relevant platform for lithium niobate integrated nanophotonics.
Photoluminescence (PL) measurements from implanted regions reveal Stark-split
4f-4f transitions consistent with bulk Er-doped lithium niobate, indicating
similar lattice occupation. Temperature-dependent PL measurements from 300 K to
5 K exhibit conventional behaviour down to approximately 50 K, followed by a
marked decrease in the emission intensity and lifetime. This anomaly is
attributed to a suppression of the pyroelectric response in LiNbO3 at low
temperatures, which affects local electric fields and, consequently, Er3+
emission. The sensitivity of the PL response to the modulation frequency and
polarization of the 980 nm excitation light is also consistent with possible
mechanisms linking thermal effects and internal fields arising in the thin
film. The results demonstrate a method for the targeted doping with Er3+ ions
into the most widely used cut of TFLN for integrated photonic devices and
provide further important considerations for their exploitation in cryogenic
quantum devices.

Watt-level ultrafast 1.75 μm laser system based on thulium-doped core and terbium-doped cladding fluoride fibers

Authors: Dina Grace Banguilan, Yuto Iye, Kazuhiko Ogawa, Eiji Kajikawa, Takao Fuji

Published: November 6, 2025

We report watt-level femtosecond pulses in the 1.75 $\mu$m region using a
thulium-doped core, terbium-doped cladding fluoride (Tm:Tb:ZBLAN) fiber laser
system. The seed pulse is generated through stimulated Raman scattering in a
silica fiber pumped by an erbium-doped fiber laser. The soliton is subsequently
amplified through a multi-stage Tm:Tb:ZBLAN amplifier. The tunability of our
chirped fiber Bragg grating stretcher, matched with a Treacy compressor,
compresses the pulse to 217 fs. Our system generates ~250 nJ of single-pulse
energy, with a corresponding average power of ~1 W at a 4 MHz repetition rate.
The laser system is suitable for multiphoton microscopy.

Cost Reducing Adiabatic Compressed Air Energy Storage for Long Duration Energy Storage Applications

Authors: Danlei Yang, Yang Wang, Jihong Wang, Zhenhua Rui, Wei He

Published: November 5, 2025

Long-duration energy storage (LDES) is vital for decarbonizing the energy
system but faces economic challenges, including high upfront costs, low trading
frequency, and limited revenue in current electricity markets. Compressed Air
Energy Storage (CAES) is a promising LDES solution, though its economic
viability, especially for long storage durations beyond lithium-ion battery
capabilities, remains unclear. To address this, here we compiled and analyzed a
global emerging adiabatic CAES cost database, showing a continuous cost
reduction with an experience rate of 15% as capacities scaled from 10MW to
100MW. Our lifecycle discounted cash flow analysis suggests that adiabatic CAES
could achieve economic viability for 10-100 hour storage durations,
particularly with optimal geological siting to lower storage costs. This
economically viable LDES option will enable large-scale grid balancing and
support renewable integration over multi-day periods, making it a valuable
asset for advancing deep decarbonization of energy systems.

Ultrafast Reconfigurable Topological Photonic Processing Accelerator

Authors: Wenfeng Zhou, Xin Wang, Xun Zhang, Yuqi Chen, Min Sun, Jingchi Li, Xiong Ni, Yahui Zhu, Qingqing Han, Jungan Wang, Chen Yang, Bin Li, Feng Qiu, Yikai Su, Yong Zhang

Published: November 5, 2025

The rise of artificial intelligence has triggered exponential growth in data
volume, demanding rapid and efficient processing. High-speed, energy-efficient,
and parallel-scalable computing hardware is thus increasingly critical. We
demonstrate a wafer-scale non-volatile topological photonic computing chip
using topological modulators. Leveraging the GHz-speed electro-optic response
and nonvolatility of ferroelectric lead zirconate titanate (PZT) thin films via
topological photonic confinement, Our chip enables thousand-fold faster
reconfiguration, zero-static-power operation, and a computational density of
266 trillion operations per second per square millimeter . This density
surpasses that of silicon photonic reconfigurable computing chips by two orders
of magnitude and thin-film lithium niobate platforms by four orders of
magnitude. A 16-channel wavelength-space multiplexed chip delivers 1.92 TOPS
throughput with 95.64% digit-recognition accuracy and 94.5% precision for
solving time-varying partial differential equations. Additionally, the chip
supports functional reconfiguration for high bandwidth density optical I/O.
This work establishes ferroelectric topological photonics for efficient
high-speed photonic tensor processing.

Lithium Niobate Vertical Cavity Electro-Optic Modulator

Authors: Jikun Liu, Weiye Liu, Wei Wu, Ziang Guo, Changrui Zhu, Lun Qu, Pengfei Zhu, Yiting Zhang, Zhihao Chen, Qinglian Li, Dahuai Zheng, Hongde Liu, Shaowei Wang, Wei Cai, Mengxin Ren, Jingjun Xu

Published: November 4, 2025

Electro-optic modulators (EOMs) are vital for optical imaging and information
processing, with free-space devices enabling LiDAR and beam control. Lithium
niobate (LN), powered by the strong Pockels effect and scalable LN-on-insulator
(LNOI) platform, has become a leading material for high-performance EOMs. Here
we realize a vertical-cavity EOM in which an LN membrane is sandwiched between
two photonic crystal (PhC) mirrors with integrated electrodes. The cavity
supports sharp defect-mode resonances that shift efficiently under the Pockels
effect, enabling strong modulation of transmission. Experiments show a depth of
43 % at 50 V and a bandwidth of 5 MHz. This architecture combines free-space
compatibility with fabrication simplicity, opening new routes to compact
electro-optic platforms for ranging, holography, and beam steering.

Topological Soliton Frequency Comb in Nanophotonic Lithium Niobate

Authors: Nicolas Englebert, Robert M. Gray, Luis Ledezma, Ryoto Sekine, Thomas Zacharias, Rithvik Ramesh, Benjamin K. Gutierrez, Pedro Parra-Rivas, Alireza Marandi

Published: November 3, 2025

Frequency combs have revolutionized metrology, ranging, and optical clocks,
which have motivated substantial efforts on the development of chip-scale comb
sources. The on-chip comb sources are currently based on electro-optic
modulation, mode-locked lasers, quantum cascade lasers, or soliton formation
via Kerr nonlinearity. However, the widespread deployment of on-chip comb
sources has remained elusive as they still require RF sources, high-Q
resonators, or complex stabilization schemes while facing efficiency
challenges. Here, we demonstrate an on-chip source of frequency comb based on
the integration of a lithium niobate nanophotonic circuit with a semiconductor
laser that can alleviate these challenges. For the first time, we show the
formation of temporal topological solitons in a on-chip nanophotonic parametric
oscillator with quadratic nonlinearity and low finesse. These solitons,
independent of the dispersion regime, consist of phase defects separating two
$\pi$-out-of-phase continuous wave solutions at the signal frequency, which is
at half the input pump frequency. We use on-chip cross-correlation for temporal
measurements and confirm formation of topological solitons as short as 60 fs
around 2 $\mu$m, in agreement with a generalized parametrically forced
Ginzburg-Landau theory. Moreover, we demonstrate a proof-of-concept turn-key
operation of a hybrid-integrated source of topological frequency comb.
Topological solitons offer a new paradigm for integrated comb sources, which
are dispersion-sign agnostic and do not require high-Q resonators or high-speed
modulators and can provide access to hard-to-access spectral regions, including
mid-infrared.

Directional atomic layer etching of lithium niobate using Br-based plasma

Authors: Ivy I. Chen, Mariya Ezzy, Emily Hsue-Chi Shi, Clifford F. Frez, Suraj, Lin Yi, Mahmood Bagheri, James R. Renzas, Alireza Marandi, Frank Greer, Austin J. Minnich

Published: November 3, 2025

Lithium niobate (LiNbO$_3$, LN) is a nonlinear optical material of high
interest for integrated photonics with applications ranging from optical
communications to quantum information processing. The performance of on-chip
devices based on thin-film lithium niobate (TFLN) is presently limited by
fabrication imperfections such as sidewall surface roughness and geometry
inhomogeneities over the chip. Atomic layer etching (ALE) could potentially be
used to overcome these difficulties. Although an isotropic ALE process for LN
has been reported, performing LN fabrication completely with ALE faces several
challenges, including the lack of a directional ALE process for pattern
transfer and the redeposition of involatile compounds. Here, we report a
directional ALE process for LN consisting of sequential exposures of
HBr/BCl$_3$/Ar plasma for surface modification and Ar plasma for removal. The
HBr chemistry is found to decrease redeposition compared to F- and Cl-based
plasmas, which we attribute to the higher vapor pressures of Br-based products.
A grating pattern etched entirely by the process (total etch depth of 220 nm)
exhibits no aspect ratio dependent etching (ARDE) down to the smallest tested
gap of 150 nm, in contrast to ion milling in which ARDE manifests even at 300
nm gaps for the same etch depth. The HBr plasma chemistry is also found to
support an isotropic process consisting of sequential exposures of H$_2$ plasma
and HBr/BCl$_3$/Ar plasma. These processes could be used together to perform
the complete fabrication process for TFLN devices, eliminating imperfections
arising from ion milling.

Detailed spectroscopic and photometric analysis of the remarkable planet-hosting wide binary system HD 202772A/B

Authors: Emiliano Jofré, Yilen Gómez Maqueo Chew, Romina Petrucci, Carlos Saffe, Jhon Yana Galarza, Paula Miquelarena, María Paula Ronco, Matías Cerioni, Camila Zuloaga, Eder Martioli, Francesca Faedi, Cintia Martínez, Leila Saker, Jorge Meléndez, Matías Flores Trivigno, Leslie Hebb, Rodrigo Díaz, Luciano García

Published: November 3, 2025

We conducted a detailed spectroscopic and photometric characterization of the
planet-hosting wide binary HD 202772A/B. No planet has been detected around HD
202772B, whereas HD 202772A, more evolved than its companion and near the end
of its main-sequence (MS) phase, hosts a transiting hot Jupiter. The system has
one of the hottest components ($T_{\mathrm{eff}; A} \sim 6440$ K) and one of
the largest surface gravity differences between components ($\Delta\log g_{A-B}
\sim 0.4$ dex) among MS planet-hosting wide binaries. Using a global fit
including our stellar parameters, radial velocities, and new TESS data, we
derive refined properties of the planet orbiting HD 202772A, finding it to be
the most irradiated hot Jupiter known in a wide binary. We also constrain the
presence of additional transiting planets around HD 202772A and new transiting
planets around HD 202772B using TESS photometry. We derive high-precision,
strictly differential abundances for 27 species based on Gemini-GRACES spectra.
HD 202772A shows lower lithium abundance (by 0.45 dex) relative to B,
consistent with their stellar parameter differences. We also detect a small but
significant enhancement in refractory elements in HD 202772A, particularly
those with condensation temperatures above 1400 K (+0.018 $\pm$ 0.004 dex). We
explored several scenarios to explain the observed chemical anomalies. Our
analysis suggests that rocky planet engulfment, primordial inhomogeneities, and
$\delta$ Scuti-related effects are unlikely to fully account for the chemical
pattern. Instead, the differences observed in certain refractory elements might
support atomic diffusion as the most plausible explanation.

Multiplexed Catheter-Integrated Pressure Sensing System for Endoluminal Interventions

Authors: Xiaotong Guo, Qindong Zheng, Jinshi Zhao, Bing Li, Eric Morgan Yeatman

Published: November 2, 2025

Advances in flexible catheters pave the way for minimally invasive diagnosis
and treatment of luminal organs and tubular structures through endoluminal
interventions. A key challenge is in establishing non-constraining pressure
monitoring at the interfaces between medical catheters and intraluminal anatomy
exhibiting curvilinear contours, structural variability, and time-dependent
physiological motion. This work presents a scalable and multi-purpose pressure
sensing system for multidirectional monitoring of tissue interactions,
establishing a robust solution for deploying diagnostic and therapeutic
instruments in various types of endoluminal interventions. This approach
provides an integrated system encompassing pressure sensors, catheters, and
signal acquisition devices. A poly (vinylidene fluoride-co-trifluoroethylene)
(P(VDF-TrFE)) film is miniaturized and configured into a multiplexed
piezoelectric-based pressure sensor, providing flexibility and scalability in
conforming to medical catheters with curved surfaces. The catheter is
fabricated with a cost-effective and highly scalable fiber drawing technology,
establishing a means of fast prototyping catheters with bespoke structures for
sensor integration and medical instrument integration. The system achieves
enhanced pressure detection sensitivity and a comparable sensing range,
compared with state-of-the-art catheter-integrated sensors. Through in-vitro
phantom studies, the system performs precise multi-directional sensing within
various clinical endoluminal scenarios, showing its potential in digitalizing
tissue interactions during endoluminal interventions.

Altermagnetism and Anomalous Transport in Ag$^{2+}$ Fluorides: KAgF$_3$ and K$_2$AgF$_4$

Authors: Xiao Nan Chen, Sining Zhang, Zhengxuan Wang, Minping Zhang, Guangtao Wang

Published: November 1, 2025

Compounds containing Ag$^{2+}$ ion with 4d$^9$ configuration will cause
significant Jahn-Teller distortions and orbital ordering. Such orbital order is
closely related to the magnetic coupling, according to Goodenough-Kanamori
Ruels. Our first-principles calculations reveal that the ground state of
KAgF$_3$ exhibits collinear A-type antiferromagnetic (A-AFM) ordering
accompanied by C-type orbital ordering. In contrast, K$_2$AgF$_4$ adopts a
collinear intralayer antiferromagnetic configuration coupled with ferromagnetic
orbital ordering. The A-AFM KAgF$_3$ presents distinct altermagnetic responses,
including: (i) prominent anomalous transport effects, such as anomalous Hall
conductivity (AHC), anomalous Nernst conductivity (ANC), and thermal anomalous
Hall conductivity (TAHC); and (ii) strong magneto-optical responses, manifested
through pronounced Kerr and Faraday effects. On the other hand, K$_2$AgF$_4$
behaves as a conventional collinear antiferromagnet preserving $\mathcal{PT}$
symmetry, hence precluding the emergence of an anomalous Hall response.