Physicist · Thin-film optics · AI × code

Light into possibility.

I’m yElixir, a physicist specializing in thin-film optics. I study how light behaves — and how carefully designed layers can shape it. The same curiosity drives the software I build with AI.

Start a conversation Explore the lab

01 Light — a different wavelength

Light reveals possibility.

A starting point for curiosity.

Light carries information about the world. I approach it as a physicist: observing what happens, asking why, and looking for principles that make a complex system understandable.

A single beam reveals a spectrum of possibilities.
1.1 Wave propagation
$E (z, t) = E_{0} \cos (k z - ω t)$
A monochromatic plane wave; k = 2πn / λ₀.
Different wavelengths respond differently to the same material.
1.2 Refraction
$n_{1} \sin θ_{1} = n_{2} \sin θ_{2}$
Snell’s law relates propagation angles at an interface.
Understanding begins by noticing what others might overlook.
1.3 Material dispersion
$n = n (λ)$
A wavelength-dependent index separates the components of light.

02 Optics — physics is the foundation

Think in waves.

Patterns, not just appearances.

Optics is the study of how light travels and interacts with matter. Phase, amplitude, and wavelength explain why waves reinforce or cancel one another — and why the same light can produce very different outcomes.

Two waves can occupy the same space.
2.1 Field superposition
$E = E_{1} + E_{2}$
Fields add; intensity depends on the squared field amplitude.
Their relative phase determines how they combine.
2.2 Coherent interference
$I = I_{1} + I_{2} + 2 \sqrt{I_{1} I_{2}} \cos Δ φ$
For mutually coherent waves with the same polarization.
Interference turns an invisible relationship into a visible pattern.
2.3 Optical path difference
$Δ φ = \frac{2 π Δ OPL}{λ_{0}}$
Propagation phase difference; interface phase shifts are additional.

03 Thin films — my field of specialization

Thin films. Precise control.

Small layers. Deliberate effects.

Thin-film optics is my core specialty. Layer thickness and refractive index shape the phase of reflected and transmitted light. By understanding these interactions, optical coatings can be designed around a desired spectral response.

Every boundary reflects and transmits part of the incoming light.
3.1 Phase thickness
$δ_{j} = \frac{2 π n_{j} d_{j} \cos θ_{j}}{λ_{0}}$
Optical thickness governs the phase accumulated in a layer.
Optical thickness changes the phase accumulated within a layer.
3.2 Layer characteristic matrix
$M_{j} = [\begin{matrix} \cos δ_{j} & i \sin δ_{j} / η_{j} \\ i η_{j} \sin δ_{j} & \cos δ_{j} \end{matrix}]$
ηⱼ is optical admittance; the imaginary signs follow the chosen field convention.
The response comes from the layers working together.
3.3 Stack response
$M = M_{1} M_{2} \dots M_{N} R = {| r |}^{2}$
Layer order and boundary admittances determine the amplitude reflection coefficient r.

04 AI × code — from a question to a working tool

Ideas become software.

Scientific thinking, applied.

I also develop software with AI and provide consulting support. I use it to explore approaches, build prototypes, and refine practical tools — while keeping the problem, assumptions, and evaluation in view.

Start by defining the problem and what a useful result looks like.
4.1 From parameters to predictions
$p = (d_{1}, \dots, d_{N}) \to R (λ; p)$
An example of turning a physical model into a computational tool.
Build with AI, then inspect the assumptions and implementation.
4.2 Define an objective
$L (p) = \sum_{k} w_{k} {[R (λ_{k}; p) - R_{k}^{*}]}^{2}$
A weighted error compares a predicted spectrum with a target.
Test, learn, and refine. A working result matters more than a demo.
4.3 Evaluate sensitivity
$Δ R \approx \sum_{j} \frac{\partial R}{\partial d_{j}} Δ d_{j}$
First-order sensitivity connects parameter changes to optical performance.

05 Possibility — the thread that connects it all

Stay curious. Make it real.

One perspective. Many directions.

Physics gives me a method: ask clearly, examine assumptions, and follow the evidence. I bring that same reasoning to optics, software, education, and business consulting. Different fields, one disciplined approach to making things work.

Start with pieces: a question, a principle, an idea.
5.1 Physical foundations
$\nabla \times E = - \frac{\partial B}{\partial t}$
Faraday’s law: changing magnetic fields and electric fields are linked.
Sound reasoning carries across disciplines — from the lab to a business decision.
5.2 Mathematical perspectives
$F (ω) = \int_{- \infty}^{\infty} f (t) e^{- i ω t} d t$
A Fourier transform reveals a signal through its frequency components.
yElixir. Grounded in physics. Open to what comes next.
5.3 A shared way of thinking
observe → model → compute → understand
yElixir — physics, optics, and software in conversation.

01 Light
02 Optics
03 Thin films
04 AI × Code
05 Possibility

00:00 / 01:15

Not separate interests. A shared way of thinking.

About — the person behind yE

Rooted in physics. Open to possibility.

I’m yElixir, a physicist specializing in optics and thin-film optics. I study how light behaves — and how carefully designed layers can shape it.

The same curiosity takes me into software. I use AI to explore ideas, develop tools, and support practical development and consulting work. The starting point is always the problem; the goal is something useful, understandable, and open to improvement.

My work also extends to education, operations, business, and startup consulting — guided by the same first-principles approach I bring to physics.

Physics & optics: Understanding light through physical principles, observation, and careful reasoning.
Thin-film optics: Exploring how layer thickness and refractive index influence reflection, transmission, and interference.
AI & software: AI-assisted development and consulting, from an initial question to a useful working tool.

Lab — curiosity in practice

Curiosity, in practice.

Fig. 1 — My YouTube channel

Science & Optics Shorts

I create and publish short videos exploring science, with a particular focus on optics. A place to share the ideas behind light, in a more accessible form.
Visit the channel

Six gameplay stills of the first Mega Man X stage, each built by a different AI model from the same prompt. — Fig. 2 — AI experiment

Mega Man X Bench

One prompt. Many models. An experiment in what AI can build.

Stills, left to right: Claude Fable 5.1, Claude Opus 5.5, DeepSeek V4.1 Flash, ChatGPT Astra 6, ChatGPT Sol 6, Grok 4.7.
Open the bench

Layer pairs3 Design wavelength λ₀550 nm Angle of incidence θ0°

Reflected

Transmitted

Fig. 3 — Interactive

Thin-film playground

A quarter-wave (HL)ᴺ stack on glass: nH = 2.10, nL = 1.46. Change the design and watch the reflected and transmitted colors follow the physics. Computed live with characteristic matrices.

Consulting — outside the lab

Good reasoning travels.

First principles. Clear questions.
Decisions that stand up to scrutiny.

Physics teaches you to ask precise questions, uncover assumptions, and test explanations against evidence. That way of thinking is equally valuable when shaping a business, improving everyday work, or helping someone learn.

Education and consulting are already part of what I do. I bring the same discipline to operations, business, and early-stage ventures: define the problem, understand the constraints, and turn complexity into a clear next step. The subject changes; sound reasoning carries across.

01
Define
The problem, and what a useful result looks like.
02
Constrain
Understand the constraints; uncover the assumptions.
03
Test
Check explanations against evidence.
04
Decide
Turn complexity into a clear next step.

Currently supporting GRASSKIM A specialist in golf course management education and advisory consulting. My role: business & startup consulting

Contact

Let’s make it real.

Optics, software, education, or an early-stage venture — tell me what you’re working on.

yelixir@yelixir.dev

Light into possibility.

Light reveals possibility.

Think in waves.

Thin films. Precise control.

Ideas become software.

Stay curious. Make it real.

Rooted in physics. Open to possibility.

Curiosity, in practice.

Science & Optics Shorts

Mega Man X Bench

Thin-film playground

Good reasoning travels.

Define

Constrain

Test

Decide

Let’s make it real.