Chia-Chin Chiang

The increasing bandwidth demand of artificial-intelligence computing and data-center interconnects has driven silicon photonic optical engines toward higher capacity, compact packaging, and improved scalability. This work presents the packaging design and characterization of a completed 16-channel silicon photonic transmitter module for a 1.6 Tb/s-class optical engine. The module integrates an IMEC-fabricated silicon photonic chip, fiber-array edge-coupling interfaces, wire-bond submounts, PAM4 driver circuits, per-channel MZM heaters, and module-level thermoelectric cooling. A custom submount reduced the highly nonuniform wire-bond distance of 255.98–1788.48 μm to approximately 275.26 μm and provided a simulated packaged-path −3 dB bandwidth of approximately 32 GHz. Fiber-array monitor-port scans showed transverse alignment tolerances of approximately 4–6 μm; after accounting for the nominal 1% monitoring tap and a separately calibrated 4 dB grating-coupler-to-MMF path, the effective packaged input-coupling estimate at 1310 nm was approximately 3.77 dB. All 16 channels were independently verified at 53.125 GBaud PAM4, corresponding to 106.25 Gb/s per lane, and the completed module supports concurrent activation of all lanes. Because the Keysight N1000A optical sampling oscilloscope (Keysight Technologies, Inc., Santa Rosa, CA, USA) accepts one optical input at a time, the eye diagrams and metrics were acquired by sequentially selecting the observed channel and do not constitute a simultaneous 16-channel crosstalk measurement. Across the 16 channels, the measured optical power, OMA, ER, TDECQ, and RLM ranged from −0.09 to 0.30 dBm, 1.141 to 1.267 dBm, 3.037 to 3.055 dB, 3.09 to 3.18 dB, and 0.956 to 0.981, respectively. The measured module-level TEC power was 1.2 W. Using the same nominal 1.6 Tb/s data-rate denominator, the estimated energy consumption is 3.95 pJ/bit for the transmitter electronics excluding the external lasers and TEC and 7.83 pJ/bit when the external laser operating power and measured module-level TEC power are included. These results demonstrate a practical package-level proof of concept for scalable 1.6 Tb/s-class silicon photonic transmitters.

A phosphor-in-glass film on sapphire (PiGoS) structure was fabricated by electrostatic spraying as a low-porosity, thickness-controllable color-conversion layer for LED fog-lamp applications. YAG:Ce ³⁺ phosphor and borosilicate glass powders were mixed at a weight ratio of 7:3, deposited onto 100-µm-thick sapphire substrates, sintered at 740 °C, and polished to thicknesses of 150–250 µm. Structural and optical analyses confirmed that the YAG:Ce ³⁺ crystalline phase and characteristic Ce ³⁺ emission were preserved after fabrication. Micro-CT results showed that the pore-volume fraction decreased from 8.7% in conventional PiG to 2.3% in PiGoS. The optimized 150 µm PiGoS achieved the highest luminous efficacy of 109.4 ± 3 lm/W, representing an approximately 8% improvement over the 150 µm PiG reference, with a 6.3% quantum-efficiency enhancement. As the PiGoS thickness increased from 150 to 250 µm, the calculated pore volume increased from 9.32 to 27.96 mm ³ , while the luminous efficacy decreased to 94.8 ± 3 lm/W. Wafer-level mapping further confirmed stable optical uniformity across diced PiGoS chips. These results demonstrate that electrostatically sprayed PiGoS is a promising wafer-scalable phosphor-conversion platform for high-efficiency LED fog lights.

This study presents a dual-mode strain gauge integrated with Fiber Bragg Grating (FBG) technology for simultaneous measurement of tensile and compressive strains. A flexible hinge-bridge structure is employed to amplify longitudinal deformation into transverse strain, enhancing sensitivity and enabling real-time temperature compensation through a paired-FBG configuration. The sensor was designed and optimized using Finite Element Method (FEM) analysis, fabricated from AISI 304 stainless steel via laser cutting, and experimentally validated under controlled loading. The results demonstrate high sensitivities of 8.08 pm/με (tension) and 26.56 pm/με (compression) with excellent linearity (R² up to 0.987) and FEM–experiment agreement within 3.5% deviation. The proposed sensor achieves high repeatability, temperature stability, and bidirectional operation, offering a compact and reusable solution for precision strain and structural health-monitoring applications.

Polarization-diversified loop-based fiber comb filters have required at least two wave plates per birefringence element for polarization interference to achieve continuous wavelength tunability in high-order comb spectra, including flat-top or narrowband comb spectra. By incorporating variable wave plates (VWPs) whose orientation and retardance can be arbitrarily modified, we propose a continuously wavelength-tunable flat-top polarization-diversified fiber loop (PDFL) filter that utilizes one wave plate per polarization-maintaining fiber (PMF) segment used as a birefringence element to generate polarization interference. The proposed PDFL filter consists of a fiber-pigtailed polarizing beam splitter (PBS) to form the PDFL, two PMF segments, and two VWPs, each of which is located in front of each PMF segment. The slow-axis orientation of the PMF segment directly connected to the PBS is set at 22.5° with respect to the horizontal axis of the PBS to ensure optimal visibility of the comb spectrum. Based on the Jones calculus, we theoretically derived the filter transmittance, and the orientation angle (OA) and retardance sets of the two VWPs, which can introduce continuous extra phase shifts from 0° to 360° in the flat-top transmittance function, were found from the filter transmittance. The theoretical flat-top comb spectra calculated from these OA and retardance sets could corroborate the continuous wavelength tunability of the proposed filter. In particular, the wavelength tunability was also confirmed by experimental verification.

This study presents a glucose concentration detection system based on a microfluidic chip integrated with a Fabry-Perot interferometer optical fiber sensor (FPIOFS). The Fabry-Perot resonator is positioned on the bottom plate of the detection area, where a silver (Ag) thin film with high reflectivity in the infrared range is sputtered, in conjunction with a single-mode fiber end face, to generate the Fabry-Perot resonance effect, thereby enhancing measurement sensitivity. The microfluidic chip was fabricated using a laser cutting machine and thermal pressing method, allowing easy and rapid production. The system exhibits high signal stability, repeatability, and linearity in glucose concentration measurements. The detection range spans from 2 mg/dL to 1000 mg/dL, with a sensitivity of 4.655x10^-3 nm/(mg/dL) and a high linearity of 0.905. The combination of optical fiber sensing and microfluidics presents a promising approach for non-invasive and efficient biomedical analysis, offering new possibilities for point-of-care diagnostics and personalized medicine.

Achieving high luminous efficacy and spectral uniformity in full-spectrum white LEDs (FS-WLEDs) remains challenging due to phosphor sedimentation during encapsulant curing. This study introduces an SiO₂ aerogel-doped composite that provides direct evidence of sedimentation suppression via Ce-line scan EPMA. Incorporating 1.0 wt% SiO₂ aerogel into a four-phosphor InGaN-based FS-WLED package not only mitigated phosphor precipitation but also enhanced light conversion efficiency, leading to a 7.8% increase in luminous efficacy (110 lm/W), an average color rendering index improvement from 91 to 95, and a 194 K reduction in angular color temperature deviation. Long-term tests (1008 h at 150°C) confirmed its stability. This scalable, low-cost approach combines sedimentation control, material savings, and proven reliability for next-generation solid-state lighting.

This study presents a hybrid approach to enhance the optical performance of phosphor-in-glass (PiG) structures for white light-emitting diodes (WLEDs) by integrating laser-fabricated microlens arrays (MLAs) onto the phosphor surface. The MLA structures were directly patterned using laser direct writing and drilling, offering precise photon redirection without compromising the thermal or mechanical stability of the PiG material. By varying the microlens spacing (100, 105, 120, and 135 μm), the effect of structural parameters on light extraction and angular emission was systematically investigated. Experimental results show that the sample with 120 μm spacing achieves optimal performance, increasing the emission angle from 80° to 120° and enhancing luminous efficacy by 12.5%. The scattering ratio improves from 51.4% to 80.3%, while the color conversion efficiency increases from 64.7% to 74.6%. Ray-tracing simulations based on geometric optics confirm the observed improvements and reveal the underlying mechanisms of enhanced light scattering and reduced internal reflection. The proposed fabrication method is scalable, maskless, and compatible with high-power LED packaging. These findings demonstrate a practical and effective strategy for improving both angular distribution and luminous efficiency in next-generation WLEDs, particularly for automotive and solid-state lighting applications.

This study introduces a novel plastic optical fiber probe for detecting mercury ions in solution. The sensor is designed to be cost-effective and enhance sensing capabilities by applying a layer of nanocomposite film to the end face of the plastic optical fiber. This film is composed of silver nanoparticles (AgNPs) molecularly imprinted with sodium alginate (SA) and embedded in polyvinyl alcohol (PVA). The research reveals a strong correlation between the thickness of the coated film and the sensor's sensitivity. The results demonstrate that with a film thickness of 5.2 μm, the probe exhibits a wavelength sensitivity of 303.825 a.u./ppm and a high linearity of 0.955 within the mercury ion concentration range of 0.01 ppm to 10 ppm. Furthermore, the study discovers a highly linear relationship between film thickness and sensitivity, reaching a value of 0.975. This research is consistent with development of Nations Sustainable Development Goal SDG 3.