The hottest Photonics Substack posts right now

A true laser needs three things: a gain medium for stimulated emission, a pump that creates a population inversion, and a cavity that gives feedback so one wavelength is amplified. Stimulated emission makes identical photons so the light can cascade into a coherent beam.
Almost anything with suitable electronic states and some feedback can be made to lase if you pump it hard enough — people have made lasers from dyed jell‑O, peacock feathers, biological tissue, edible microlasers, and even parts of planetary atmospheres.
Practical and fundamental limits stop some things from lasing: losses that grow with pump power and the rapidly shrinking upper‑state lifetime at high frequencies mean materials like silicon and very high‑energy ranges (UV, X‑ray, gamma) are effectively impossible to lase with realistic pumps.

Co-packaged optics (CPO) is moving from labs to shipping products and will be the key way to scale high-bandwidth, low-latency AI scale-up networks because it offers much higher bandwidth density and longer reach than copper.
CPO cuts or removes power-hungry DSPs and long-reach SerDes, unlocking big energy and density gains by integrating optical engines near the chip and using enablers like TSMC COUPE, modulators (MRM/MZM/EAM), WDM, and FAUs.
Wide adoption still faces real hurdles — supply chain, manufacturability, reliability, serviceability and standards — so early wins will be limited, but hyperscaler commitments and compelling scale-up economics should drive a larger ramp later this decade.

Science is developing organ perfusion systems that can keep organs alive outside the body for much longer, which could turn transplants into scheduled procedures, increase usable donations, and enable organ banking or swapping.
Self-experiments with high-dose psilocybin showed rapid improvements in mental health, brain plasticity, metabolic control, and inflammation. These results suggest psychedelics might become part of longevity strategies for some people, though risks remain.
Researchers are 3D-printing tiny helix structures that manipulate terahertz waves, unlocking a hard-to-reach part of the electromagnetic spectrum for telecom, sensing, and even polarization-encoded data. A year-end scientific review also highlights wide-ranging, high-impact advances across many fields, signaling rapid progress.

The semiconductor industry is shifting from making transistors smaller to using specialized chiplets that connect more easily. This means the focus is on improving system-level architecture rather than just the size of chips.
Glass is being considered as a better material than silicon for chip packaging because it maintains its shape when heated and allows for better integration of photonic components. This could help simplify the manufacturing process and improve performance.
Both quantum and classical computing share similar needs for efficient data transfer, which is leading to exciting new developments in the use of photonics. Companies that master these photonic connections may gain a significant advantage in the future of computing.

Human brain uses less energy than computers for similar tasks like running neural networks
Silicon photonics can improve energy efficiency in running neural networks by replacing electrical connections with light-based ones
Photonic meshes have potential for great power efficiency, but face challenges in accuracy and scalability

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Gallium nitride (GaN) could be better for photonics than silicon. It can generate light directly on the chip, while silicon needs separate lasers, making it less efficient.
The constraints of using specific wavelengths for light transmission are starting to disappear. In short-distance connections, like inside data centers, it's possible to use a wider range of wavelengths.
There's no perfect material for every need. Using different materials for different tasks could lead to better solutions in fields like quantum computing and RF photonics, making the industry more versatile.

Optical computing uses light particles instead of electrons for computations, promising faster processing speeds and energy efficiency.
Opto-electronic computing is close to commercialization, combining optical and electronic functions to leverage speed and bandwidth advantages.
Optical computing faces challenges in adoption due to the need for changing components and manufacturing processes, but has potential for high-performance tasks like AI training.

Light is much faster than electricity and creates less heat, which is great for computers. However, using light instead of electricity in all parts of computers is really hard to do.
One big challenge is that we don't have good ways to store information using only light yet. Current storage methods wear out too quickly, making them less reliable.
Companies are focusing more on using light for connecting computers instead of for thinking tasks. This shift allows them to sell products now while working on more complex uses in the future.