Bracara Photonics
Open Studio

Devices we have made.

Flat optics and micro-optics from our cleanroom processes, imaged by SEM and characterized in the lab. Select an image to see it full size.

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A fabricated flat lens held in a gloved hand, imaging the INL sign on the building behind it.
ø 18 mm diffractive Fresnel lens

Diffractive lens · photo

Large-aperture diffractive Fresnel lens

A diffractive Fresnel lens with an 18 mm aperture, held up against the INL building and imaging it.

Aperture
ø 18 mm
Microscope image of the pixels of a fabricated multilevel hologram phase mask.
Detail of the phase mask pixels

Hologram / CGH · microscope

Multilevel hologram phase mask

Detail of a multilevel hologram phase mask. The height of each pixel sets the phase it adds to the light, and together the pixels form the target image.

SEM image, tilted 40°, of the outer zones of a multilevel achromatic Rose lens with a 25 mm focal length: chevron-shaped multilevel zones ending at the lens edge.
f = 25 mm, lens edge. SEM, 40° tilt
SEM image, tilted 40°, of the centre of a multilevel achromatic Rose lens with a 50 mm focal length: star-shaped zone boundaries around a smooth central zone.
f = 50 mm, lens centre. SEM, 40° tilt
Measured focal spots of the achromatic Rose lens at 450, 500, 550, 600 and 650 nm: one compact spot at every wavelength, with horizontal and vertical intensity profiles. Scale bar 20 µm.
Measured focal spots from 450 to 650 nm, scale bar 20 µm. F. Camarneiro et al., J. Phys. Photonics (2026)

Diffractive lens · SEM and optical characterization

Multilevel achromatic Rose lenses

Two multilevel achromatic Rose lenses, designed with the azimuthally segmented polychromatic method from our J. Phys. Photonics paper. Each angular segment focuses a different wavelength to the same plane. Measured from 450 to 650 nm, the lens forms one focal spot at every wavelength.

Focal length
25 mm and 50 mm
Groove depth
10 to 13 µm
Strehl ratio
0.38 to 0.61, 450 to 650 nm
Close-up of fabricated diffractive optics on a wafer: axicons, lenses and holograms side by side.
Multi-project wafer
A wafer of flat lenses and holograms held up in the cleanroom's yellow light.
Multi-project wafers in the cleanroom
A wafer with an array of fabricated diffractive lenses, held in a gloved hand.
Small-scale production in the cleanroom

Wafer-level fabrication · photo

From multi-project wafers to small-scale production

Many designs share one wafer, so a single run delivers axicons, lenses and holograms for several projects. The same process runs small production batches in the cleanroom.

Run size
Single sample to small batches
SEM image, tilted 40°, of a polymer axicon on glass: smooth concentric zones separated by steps.
SEM, 40° tilt

Diffractive axicon · SEM

Axicon

A multilevel axicon in polymer on a glass substrate. It turns a collimated beam into a Bessel beam with a long, narrow focal line.

Material
Polymer on glass
Groove depth
10 to 13 µm
SEM image, tilted 40°, of a beam-splitting spiral phase plate: parallel grating lines with a fork dislocation in the middle.
SEM, 40° tilt

Vortex beam generator · SEM

Beam-splitting spiral phase plate

A grating with a fork dislocation at its centre. It splits the beam and sends an optical vortex, a beam carrying orbital angular momentum, into an off-axis order.

Output
Off-axis vortex beam
Groove depth
10 to 13 µm
SEM image, tilted 30°, of a silicon master: a smooth concave cylindrical profile between two vertical walls.
Silicon master. SEM, 30° tilt
SEM image, tilted 40°, of a nickel replica: a row of convex cylindrical lenses.
Nickel replica. SEM, 40° tilt

Replication · SEM

Cylindrical lens array: master and replica

A silicon master with concave cylindrical profiles, and the nickel replica moulded from it, where the profiles become convex lenses. The master can be reused to make many replicas.

Master
Silicon
Replica
Nickel
Paper
J. Cunha et al., Micro and Nano Engineering, 2023: tolerances in grayscale lithography and RIE for 2.5D Si master molds
A fabricated Alvarez lens plate on glass, with its freeform fringe pattern visible.
Alvarez lens plate

Freeform lens · photo

Large-aperture Alvarez lens

One plate of an Alvarez lens pair. Sliding the two plates against each other changes the focal length continuously.

Material
Polymer on glass
Size
15 × 10 mm
A diffractive lens sample held in tweezers, focusing light to a bright spot with diffraction spokes on the surface below.
Focusing light to a spot

Diffractive lens · photo

Diffractive lens at focus

A fabricated diffractive lens in its holder, focusing light to a bright spot on the surface below.

Paper
D. E. Aguiam et al., Micro and Nano Engineering, 2022: large aperture diffractive lenses by greyscale lithography
The INL logo made of grating pixels, diffracting light in rainbow colours from pink to blue.
Viewed at an angle: rainbow diffraction
The same INL logo of grating pixels on a wafer, appearing blue under another lighting angle.
The same logo on the wafer

Grating pixels · photo

Structural colour by laser interference lithography

The INL logo written on a wafer with our laser interference lithography system, by raster exposure of grating pixels. Each pixel diffracts light at an angle set by its pitch, so the logo changes colour with viewing angle.

Grating pitch
Sub-µm
Exposure
Raster of grating pixels

Fabricated at INL

All devices on this page were fabricated in the INL cleanroom, International Iberian Nanotechnology Laboratory, Braga, Portugal.

Some of these devices were developed in publicly funded research projects at INL, supported by:

COMPETE 2030, Portugal 2030, co-funded by the European Union Funded by the European Union FCT, Fundação para a Ciência e a Tecnologia