Polychromatic liquid crystal laser arrays

1
Polychromatic liquid crystal laser arrays P.J.W.
Hands, S.M. Morris, S. Findeisen-Tandel, C.A.
Dobson, T.D. Wilkinson, C. Gillespie, J.
Schmidtke, O. Hadeler, Q. Malik, H.J.
Coles Centre of Molecular Materials for Photonics
and Electronics (CMMPE)http//www-g.eng.cam.ac.uk
/CMMPE/
Structure of a liquid crystal laser
Chiral nematic liquid crystal DFB resonant
cavityPeriodic refractive index distributed
feedback structurePhotonic band-gap (reflection
band)Chiral pitch length determines lasing
wavelength Laser dye Gain mediumFluorescence
maximum matches lasing wavelengthAbsorption
maximum matches optical pump wavelength Pulsed
laser input Optical pump

• Focus pump laser into LC cell using lens or
  lenslet array(Array distributes energy, reducing
  optical reorientation effects)
• Focussed regions of cell emit stimulated
  emission at long band-edge of photonic band-gap
• Monochromatic laser array output (visible
  infra-red)
• Wavelength tuning with change in chiral
  pitch(Temperature, voltage, deformation, chiral
  dopant concentration)
• Laser array is recombinable into single monomode
  output(High power micromolecular organic lasers
  possible)

(Above) The photonic band gap in a chiral nematic
liquid crystal. Lasing emission occurs at the
long band-edge. (Right) Monochromatic LC laser
array emission in the red, green and blue regions
of the visible spectrum.
Polychromatic LC laser arrays
Polychromatic laser emission (red, green and
blue) from a gradient pitch liquid crystal cell.

• Gradient pitch cell
• Simultaneous multi-wavelength laser emission
• Recombinable into single white light source

Funded by an EPSRC Basic Technology Research
Grant, EP/D04894X
A CAPE project, funded by
CHIRALASE