View by Category

3D-printed immersion micro optics
Marco Wende, Kathrin Doth, Michael Heymann, Andrea Toulouse
Published Published online: 25 March 2025 , doi: 10.37188/lam.2025.019

Femtosecond 3D-printing offers tantalizing avenues for miniaturization and integration of micro optical systems. Available photoresists, however, restrain their utility in liquid immersion, especially in media with refractive indices larger than n = 1.33, such as glues or biomedical fluids. We present monolithic 3D-printed immersion optics, equipped with compact microfluidic sealing to protect the micro optical device from intrusion of liquid immersion media. We experimentally demonstrate diffraction limited performance in water, silicone-, and immersion oil, for a tailored aspherical-spherical doublet with a numerical aperture of NA = 0.625 and a footprint as small as a single mode optical fiber. Such compact monolithic immersion micro optics yield high potential to advance miniaturization for in situ biomedical sensing and robust coupling between fibers and photonic integrated circuits.

A universal high-resolution micro-patterning technique for solution-processed materials
John Leo Velpugonda, Naresh Varnakavi, Matthew Yerich, Lih Y Lin
Published Published online: 19 March 2025 , doi: 10.37188/lam.2025.015
A universal method of micro-patterning thin quantum dot films is highly desired by industry to enable the integration of quantum dot materials with optoelectronic devices. Many of the methods reported so far, including specially engineered photoresist or ink-jet printing, are either of poor yield, resolution limited, difficult to scale for mass production, overly expensive, or sacrificing some optical quality of the quantum dots. In our previous work, we presented a dry photolithographic lift-off method for pixelization of solution-processed materials and demonstrated its application in patterning perovskite quantum dot pixels, 10 µm in diameter, to construct a static micro-display. This report presents further development of this method and demonstrates high-resolution patterning (~1 µm diameter), full-scale processing on a 100 mm wafer, and multi-color integration of two different varieties of quantum dots. Perovskite and cadmium-selenide quantum dots were adopted for the experimentation, but the method can be applied to other types of solution-processed materials. We also demonstrate the viability of this method for constructing high-resolution micro-arrays of quantum dot color-convertors by fabricating patterned films directly on top of a blue gallium-nitride LED substrate. The green perovskite quantum dots used for fabrication were synthesized via the room-temperature ligand-assisted reprecipitation method developed by our research group, yielding a photoluminescent quantum yield of 93.6% and full-width half-maximum emission linewidth less than 20 nm. Our results demonstrate the viability of this method for use in scalable manufacturing of high-resolution micro-displays paving the way for improved optoelectronic applications.
Improvement of the perovskite photodiodes performance via advanced interface engineering with polymer dielectric
Andrey P. Morozov, Lev O. Luchnikov, Sergey Yu. Yurchuk, Artur R. Ishteev, Pavel A. Gostishchev, et al.
Published Published online: 18 March 2025 , doi: 10.37188/lam.2025.024
Halide perovskite-based photodiodes are promising for efficient detection across a broad spectral range. Perovskite absorber thin-films have a microcrystalline morphology, characterized by a high density of surface states and defects at inter-grain interfaces. In this work, we used dielectric/ferroelectric poly(vinylidene-fluoride-trifluoroethylene) (P(VDF-TrFE)) to modify the bulk interfaces and electron transport junction in p-i-n perovskite photodiodes. Our complex work demonstrates that interface engineering with P(VDF-TrFE) induces significant Fermi level pinning, reducing from 4.85 eV for intrinsic perovskite to 4.28 eV for the configuration with dielectric interlayers. Modifying the interfaces in the devices resulted in an increase in the key characteristics of photodiodes compared to pristine devices. The integration of P(VDF-TrFE) into the perovskite film didn’t affect the morphology and crystal structure, but significantly changed the charge transport and device performance. IV curve analysis and 2-diode model calculations showed enhanced shunt properties, a decreased non-ideality factor, and reduced saturation dark current. We have shown that the complex introduction of P(VDF-TrFE) into the absorber’s bulk and on its surface is essential to reduce the impact of the trapping processes. For P(VDF-TrFE) containing devices, we increased the specific detectivity from 1011 to ~1012 Jones, expanded the linear dynamic range up to 100 dB, and reduced the equivalent noise power to 10−13 W·Hz−1/2. Reducing non-radiative recombination contributions significantly enhanced device performance, improving rise/fall times from 6.3/10.9 µs to 4.6/6.5 µs, and achieved photo-response dynamics competitive with state-of-the-art analogs. The cut-off frequency (3dB) increased from 64.8 kHz to 74.8 kHz following the introduction of the dielectric. We also demonstrated long-term stabilization of PPD performance under heat-stress. These results provide new insights into the use of organic dielectrics and an improved understanding of trap-states/ion defect compensation for detectors based on perovskite heterostructures.
Early detection of lithium battery leakage using a highly sensitive in situ ZIF-8 membrane-coated micro-nano optical fibre
Shunfeng Sheng, Hao Li, Yi Zhang, Liangye Li, Kai Xiao, et al.
Published Published online: 12 March 2025 , doi: 10.37188/lam.2025.014

Detecting electrolyte leakage is an effective early warning approach for abnormal faults in lithium-ion batteries (LIBs) and can help mitigate safety risks such as fires and explosions. However, detecting electrolyte leakage in the early stages of LIB faults presents a significant challenge, as leaks in LIBs produce volatile organic compounds (VOCs) at parts per million levels that are difficult to detect using conventional VOC sensors. Here, an effective LIB VOC sensor using micro-nano optical fibres (MNFs) has been developed for the first time, coated with an in situ self-assembled zeolitic imidazolate framework-8 (ZIF-8) membrane as an electrolyte-sensitive layer. The abundance of pores in ZIF-8 is excellent for adsorbing a variety of VOCs, including diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, and propylene carbonate. The MNFs possess high refractive index sensitivity, enhancing the online monitoring of electrolytes. MNFs with a diameter of approximately 7 μm were assembled with four-cycle ZIF-8 of approximately 500 nm thickness, as the fabricated sensor. Through wavelength demodulation, the LIB sensor demonstrated high sensitivity, detecting 43.6 pm/ppm of VOCs and exhibiting rapid response and recovery times of typically within 10 min and 23 s, respectively, as well as a low theoretical detection limit of 2.65 ppm for dimethyl carbonate vapor with excellent reversibility. The first on-site verification of online LIB leakage monitoring demonstrated that the sensor achieved a 35 h early warning prior to full-load leakage, thus exhibiting promising prospects for applications in scenarios such as car batteries.

Integrated structure and sensorless feedback control of unimorph piezoelectric deformable mirrors
Dapeng Tian, Jian Chen, Ping Jia
Published Published online: 12 March 2025 , doi: 10.37188/lam.2025.025

Deformable mirrors are essential dynamic wavefront compensation. Among the various types of deformable mirrors with different actuation mechanisms, the unimorph piezoelectric deformable mirror (UPDM) offers distinct advantages owing to its compact size and low cost. The two most critical challenges in UPDM are electrode fabrication and deformation control. This study proposes an integrated electrode fabrication and sensorless feedback control scheme for UPDM, which simplifies the manufacturing process and enhances its performance. The electrode array is created using silkscreen printing combined with flexible printed circuit board technology, integrating electrode fabrication and electrical connection into a single step. The desired mirror deformation is achieved by introducing a closed-loop direct deformation control method based on piezoelectric self-sensing. The feedback mechanism utilizes the local strain-induced charge generated by the piezoelectric plate, effectively addressing the nonlinear behavior of the piezoelectric material. Experimental results confirm the feasibility and effectiveness of the proposed method, with the maximum relative error in the steady state phase remaining below 2%.

A comparative study of plasmonic nanoparticles for targeted photothermal therapy of melanoma tumors using various irradiation modes
Lidia Mikhailova, Elizaveta Vysotina, Maria Timofeeva, Elena Kopoleva, Van Gulinyan, et al.
Published Published online: 11 March 2025 , doi: 10.37188/lam.2025.005

Melanoma, a highly malignant and complex form of cancer, has increased in global incidence, with a growing number of new cases annually. Active targeting strategies, such as leveraging the α-melanocyte-stimulating hormone (αMSH) and its interaction with the melanocortin 1 receptor (MC1R) overexpressed in melanoma cells, enhance the concentration of therapeutic agents at tumor sites. For instance, targeted delivery of plasmonic light-sensitive agents and precise hyperthermia management provide an effective, minimally invasive treatment for tumors. In this work, we present a comparative study on targeted photothermal therapy (PTT) using plasmonic gold nanorods (Au NRs) as a robust and safe nanotool to reveal how key treatment parameters affect therapy outcomes. Using an animal model (B16-F10) of melanoma tumors, we compare the targeting abilities of Au NRs modified with two different MC1R agonists, either closely mimicking the αMSH sequence or providing a superior functionalization extent of Au NRs (4.5% (w/w) versus 1.8% (w/w)), revealing 1.6 times better intratumoral localization. Following theoretical and experimental assessments of the heating capabilities of the developed Au NRs under laser irradiation in either the femtosecond (FS)- or nanosecond (NS)- pulsed regime, we perform targeted PTT employing two types of peptide-modified Au NRs and compare therapeutic outcomes revealing the most appropriate PTT conditions. Our investigation reveals greater heat release from Au NRs under irradiation with FS laser, due to the relaxation rates of the electron and phonon temperatures dissipating in the surrounding, which correlates with a more pronounced 17.6 times inhibition of tumor growth when using FS-pulsed regime.

A Non-volatile Switchable Infrared Stealth Metafilm with GST
Cong Quan, Song Gu, Tingzhao Fu, Ping Liu, Wei Xu, et al.
Published Published online: 08 March 2025 , doi: 10.37188/lam.2025.016

In this paper, we experimentally demonstrate a non-volatile switchable infrared stealth metafilm based on high temperature resistant metal Molybdenum (Mo) and phase change material Ge2Sb2Te5(GST). By controlling the phase state of GST, the switch between the infrared stealth and the non-stealth states can be realized. Specifically, when the GST is in the amorphous state, the emissivity of the film in the 3−5 μm and 8−14 μm atmospheric window band is suppressed and can realize infrared stealth, together with a high absorption peak of 94% at 6.08 μm, which enables radiative heat dissipation; While for the crystalline state of the GST, the average emissivity is more than 0.7 in the band of 8−14 μm, and the infrared stealth function cannot be realized. When the background temperature is 100°C, the temperature difference between the two samples reaches as high as 28°C under an infrared thermal imager. Therefore, our proposed metafilm can flexibly regulate the infrared thermal radiation of the target so as to realize the switch between the infrared stealth and non-stealth state. We have fabricated the metafilm on both hard and flexible substrates. Our work holds profound significance for the study of dynamic thermal radiation control and it is set to pave the way for the practical implementation of intelligent infrared stealth technology.

Glycerol-assisted grain modulation in femtosecond-laser-induced photochemical synthesis of patterned ZnO nanomaterials
Yingchen Wang, Songyan Xue, Yinuo Xu, Jing Long, Binzhang Jiao, et al.
Published Published online: 07 March 2025 , doi: 10.37188/lam.2025.007

ZnO nanomaterials have become appealing for next-generation micro/nanodevices owing to their remarkable functionality and outstanding performance. However, in-situ, one-step, patterned synthesis of ZnO nanomaterials with small grain sizes and high specific surface areas remains challenging. While breakthroughs in laser-based synthesis techniques have enabled simultaneous growth and patterning of these materials, device integration restrictions owing to pre-prepared laser-absorbing layers remain a severe issue. Herein, we report a single-step femtosecond laser direct writing (FsLDW) method for fabricating ZnO nanomaterial micropatterns with a minimum linewidth of less than 1 μm without requiring laser-absorbing layers. Furthermore, utilizing the grain-size modulation effect of glycerol, we successfully reduced the grain size and addressed the challenges of discontinuity and non-uniform product formation during FsLDW. Using this technique, we successfully fabricated a series of micro-photodetectors with exceptional performance, a switching ratio of 105, and a responsivity of 102 A/W. Notably, the devices exhibited an ultralow dark current of less than 10 pA, more than one order of magnitude lower than the dark current of ZnO photodetectors under the same bias voltage—crucial for enhancing the signal-to-noise ratio and reducing the power consumption of photodetectors. The proposed method could be extended to preparing other metal-oxide nanomaterials and devices, thus providing new opportunities for developing customized, miniaturized, and integrated functional devices.

Miniature optical fiber accelerometer based on an in-situ 3D microprinted ferrule-top Fabry–Pérot microinterferometer
Peng Wang, Taige Li, Htein Lin, Pengcheng Zhao, Shangming Liu, et al.
Published Published online: 07 March 2025 , doi: 10.37188/lam.2025.018

Accelerometers are crucial sensors that measure acceleration resulting from motion or vibration. Compared with their electromechanical counterparts, optical accelerometers are widely regarded as the most promising technology for high-requirement applications. However, compact integration of various optical and mechanical components to create a miniature optomechanical microsystem for acceleration sensing remains a challenge. In this study, we present a miniature optical fiber accelerometer based on a 3D microprinted ferrule-top Fabry–Pérot (FP) microinterferometer. In-situ 3D microprinting technology was developed to directly print a sub-millimeter-scale 3D proof mass/thin-film reflector-integrated FP microinterferometer on the inherently light-coupled end face of a fiber optic ferrule. Experimental results demonstrate that the optical fiber accelerometer has a flat response over a bandwidth of 2 to 3 kHz and its noise equivalent acceleration is 62.45 μg/Hz under 1-g acceleration at 2 kHz. This ultracompact optical fiber interferometric accelerometer offers several distinct advantages, including immunity to electromagnetic interference, remote-sensing capability, and high customizability, making it highly promising for a variety of stringent acceleration-monitoring applications.

Colloidal quantum dots on macroscale perovskite single crystal with perfect lattice matching
Yu-Hao Deng, Yun-Gang Sang, Xiao-Wei Zhang, Yi-Fei Mao, Ren-Min Ma
Published Published online: 07 March 2025 , doi: 10.37188/lam.2025.009

Quantum dots, semiconductor crystals with nanometer-scale dimensions, exhibit adjustable chemical, electrical, and optical characteristics owing to the quantum confinement effect. However, achieving high-quality quantum dots necessitates simultaneous attainment of crystalline integrity within their cores, uniformity in size and shape, as well as effective surface passivation with charge transport functionality—challenges persist regardless of the chosen method. Here, we introduce a novel approach for synthesizing quantum-dot/perovskite heterocrystals: the Colloidal Quantum Dot-Oriented Attachment to Perovskite Single Crystal (CQD-OA-PSC) method. This method involves optimizing quantum dot growth through chemical colloidal synthesis methods, followed by their oriented attachment onto macroscopic perovskite single crystals with impeccable lattice alignment. Consequently, the CQD-OA-PSC method amalgamates the strengths of wet chemical colloidal synthesis methods and solution-based epitaxial growth, offering precise control over quantum dot size, morphology, and structure while leveraging charge transport functionality conferred by the matrix crystal. High-resolution transmission electron microscopy confirms matched lattice orientations between the perovskite matrix and quantum dots. This approach promises to yield high-quality quantum dots perovskite heterocrystals with controlled size, morphology, and optoelectronic properties, thereby holding significant potential for advancing the development of efficient optoelectronic devices.

  • First
  • Prev
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • Last
  • Total:15
  • To
  • Go