The world’s first digital laser

Prof Andrew Forbes 1,2,3,4

1 CSIR National Laser Centre, Pretoria2 Laser Research Institute, University of Stellenbosc h3 College of Physics & Chemistry, UKZN4 School of Physics, University of the Witwatersrand

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Welcome to the century of the photon! Fast, accurate and contact-free, the photon is the electron of the 21st

century

Source: Photonics21.org and Nobel.org

Communication

Storage

ClocksDevices

DIGITAL Holography

Conventional holography requires that both the laser source and the object actually exist

?X =

The idea in “digital holography” is to digitally create the desired hologram

We use LCDs as our device to display these holograms

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To find the phase or wavefront of light you play a game of “join the dots”

Φ(r)

To find the phase or wavefront of light you play a game of “join the dots”

HeNe Laser

Hologram

Reference

Object

LCD

Now we can display the hologram and modify the light

We can refresh our digital holograms at 60 Hz to move a beam (or beams) around in an arbitrary fashion

LASER Resonators

highlyreflective

partiallyreflective

HR e.g. R = 90%(i.e. T = 10%)

There are only three things needed to build a laser, but putting them together can be complicated!

CC

D

Monitor 2

PC 2

400 500 600 700 800

200

250

300

350

W0

(µm

)

R [mm]

Theory Mirror

Conventional intra-cavity beam shaping

CC

D

Monitor 2

PC 2

400 500 600 700 800

200

250

300

350

W0

(µm

)

R [mm]

Theory Mirror SLM

SLM

Monitor 1

PC 1

Video signal

SLM Driver

The digital laser concept

+ =

Vertical polarization

SLM

Brewster Window

Output CouplerPhase Amplitude

Virtually any laser mode can be created with the digital laser

DigitalHologram

Slide 19

CC

D

Monitor 2

PC 2

W0R

SLM

Monitor 1

PC 1

Video signal

SLM Driver

time

Could the refresh rate also be used? Dynamic beam shapes?

Slide 21

Slide 22

Communication

Devices

Manufacturing

Health

Example: Could we programme the digital laser to produce custom shapes for additive manufacturing?

Example: Could we programme the digital laser to produce custom shapes for additive manufacturing?

Application: Could we encode information into the patterns of light for increased bandwidth?

U = A(r) S±

cos(wt – kz)

Use the polarisation

Switch as fast as you

can

Pack in lots of colours

A

B

C

A

B

C

Popular/Tutorial articles:

MathOptics

Nature Photonics 7, 592 (2013).

Science&Vie August , 44 (2013).

arXiv: 1305.7102 (2013).

Optics and Photonics News June , 22-29 (2013).

South African Journal of Science 107, 579 (2012).

Popular Mechanics July , 72-75 (2011).

Quest 6, 10-12 (2010).

Popular Mechanics April , 50-53 (2010).

Thank You!