Samsung Patents a Pixel That Bounces Light Back Instead of Letting It Escape

By Patentlyze Team · Updated Jun 19, 2026

Samsung is patenting a pixel design that essentially bounces light back through the sensor's detector instead of letting it escape — a way to squeeze more signal out of the same amount of incoming light.

What Samsung's light-bouncing pixel design actually does

Imagine shining a flashlight through a window and most of the light just passes straight through without doing anything useful. That's roughly what happens inside a standard image sensor: light enters, the detector catches some of it, but a portion slips past without being recorded. Samsung's patent addresses that waste.

The design adds two thin layers around the photodiode — the tiny component that converts light into an electrical signal. A special optical layer on the front slightly tweaks the phase of the light (think of it like adjusting the timing of a wave), and a reflective layer on the back acts like a mirror, bouncing uncaptured light back for a second chance at being detected.

The result is that the same pixel captures more light without physically getting bigger. This is especially useful for near-infrared light, the invisible wavelengths used in Face ID-style sensors, night-vision cameras, and depth-sensing systems.

How the phase-shift layer and mirror work together

The patent describes a redesigned image sensor pixel built around three main additions to a standard photodiode:

• An optical phase-modifying layer on the front (light-receiving) side. This thin film has a lower refractive index than the photodiode material itself, which causes a so-called unidirectional π phase shift — essentially a half-wavelength timing flip — specifically tuned to near-infrared wavelengths. That shift is what makes reflected light constructively interfere (reinforce itself) inside the detector rather than cancel out.
• A passivation layer sandwiched between the phase-modifying layer and the photodiode. Passivation layers are standard in chip manufacturing — they protect the semiconductor surface from contamination and electrical defects.
• A reflective layer on the back side of the photodiode. The patent allows this to be a simple metal mirror, a thin-film stack, or a Distributed Bragg Reflector (a precisely engineered multilayer mirror that reflects only specific wavelengths very efficiently).

The combined effect is a resonant cavity: light that passes through the photodiode without being absorbed hits the back mirror, bounces forward, gets phase-adjusted by the front layer, and constructively reinforces itself on the next pass — giving the detector multiple chances to absorb each photon. The patent also references metasurfaces (ultra-thin engineered surfaces that control light at the nanoscale) as a potential variation on the same concept.

What this means for low-light and infrared photography

Near-infrared sensitivity is becoming increasingly important in smartphone and wearable cameras. Face unlock, gesture recognition, heart-rate sensors, and LiDAR-style depth mapping all depend on capturing infrared light accurately. Silicon — the standard material for image sensors — is naturally inefficient at absorbing near-infrared wavelengths, which means manufacturers either accept lower performance or use thicker, more expensive sensor materials.

Samsung's approach is an on-chip optical fix: no exotic materials, just carefully engineered thin films added during normal chip fabrication. If it works as described, future Samsung sensors could deliver better low-light and infrared performance without increasing sensor size or cost. That has obvious implications for Galaxy phone cameras and any device using Samsung's ISOCELL sensor family.

Editorial commentary on a publicly published patent application. Not legal advice.