Photonics Spectra Preview for December 2025

Semiconductor Lasers

Periodic photonic structures are fundamental to semiconductor optoelectronic devices like DFB lasers, VCSELs, and photonic crystal surface-emitting lasers (PCSELs). In these devices, the periodic designs dictate critical device performance, such as mode selection, polarization control and surface emission. The manufacturing of these sub-wavelength structures requires cost-effective, high resolution, and high-quality patterning techniques for large-volume production. This article reviews Displacement Talbot Lithography (DTL), an innovative optical lithography method, particularly suited for this purpose. DTL uniquely integrates a large wafer-scale exposure field, superior pitch accuracy, and robust reproducibility with an effectively unlimited depth of focus. These capabilities are well-suited for patterning DFB lasers and can readily accommodate phase-shifts designs that enhance single-mode stability. For VCSELs and PCSELs, DTL can be combined with a secondary exposure to define device area boundaries. Its compatibility with existing semiconductor infrastructure established DTL as a robust, scalable, and cost-effective solution for manufacturing optoelectronic devices.

Thermal Imaging and Thermal Sensors

Last year, the US National Highway Traffic Safety Administration (NHTSA) issued a rule that requires essentially all cars starting with model year 2029 to include Pedestrian Automatic Emergency Braking (PAEB) systems that operate day and night, all year, even in bad weather. The rule, which aligns with recent industry efforts to optimize the size, weight, power, and cost (SWaP-C) metric as it relates to thermal imaging systems, has served to heighten focus on the development of these systems, which have long been established in defense operations. OWL AI overviews the current need to apply SWaP-C to thermal cameras with sufficient performance to support the NHTSA requirements, so that thermal imaging can be successfully applied to automotive systems. System operating requirements are discussed, as are considerations to the image sensor design, thermal resolution, device and implementation costs, and camera optics.

Low-Light Imaging

CMOS sensors are used throughout digital cameras, telescopes, automotive sensors, and semiconductor manufacturing, and are widely utilized in/for standard applications requiring image acquisition in low-light applications. As CMOS sensors continue to evolve, with broad-based performance improvements and miniaturization, distinct advances in backside illumination, stacked CMOS architectures, and scientific CMOS (sCMOS) are proving critical in low-light environments. The result is more cost effective, more powerful imaging solutions. This article overviews these points of progress, the applications that are benefitting, and existing hurdles.

Polymer Optics

This article challenges the common assumption that aspheric surfaces are inherently more expensive than spherical ones. While this holds true for conventionally polished glass optics, it doesn’t apply to injection-molded polymer lenses. With diamond-turned mold inserts, both spherical and aspheric surfaces cost the same to produce. From a practical technical perspective, this article looks at how and why aspheres are, effectively, “free” in polymer optics — and why designers should fully leverage this advantage for their applications. The article will further explore the shift in manufacturing, the expanded design freedom, and the system-level performance improvements this enables.

Cleaning Optics

Cleaning optical components is about more than maintaining aesthetics. In high-precision systems, particularly those involving lasers, even minor contamination of the optics can lead to component failure. While contaminants — either on a coating or at the interface with the substrate — can absorb laser energy and degrade the coating or substrate surface, the presence of dust, streaks, and/or stains scatter light, which reduces the overall functionality of the laser optic. At the same time, the process of laser optics cleaning is multifaceted; it necessitates consideration of more than just the condition of the optic in question and the target application. Understanding a range of techniques, approaches to handling, and best-practices for the many distinct optical materials in use today is essential to maintaining superior performance of laser optics.

Photonic MEMS

This article examines existing technologies used in the fabrication of large aperture optical switches and introduces a novel approach that utilizes micromachining manufacturing technology, originally developed to make linear array light valves. The MEMS-based fabrication builds on conventional light valve technology to deliver a high performing optical switch, particularly suited for IR imaging, lithography, and other applications demanding high-speed switching. Generally, mechanical switches are thought of as robust but slow, which will become slower as aperture increases. In this case, Teledyne MEMS shows aperture switching rivaling solid state switching speeds fabricated from the robust materials that laser mirrors are made from. The approach could offer a cost-effective alternative to acousto-optic modulators and electronic shutters for a wide variety of applications and wavelengths.