Photonic Crystal lasers

Ajay Singh IIT Delhi

Photonic crystals ??

Crystals composed of periodic dielectric or metallo- dielectric

nanostructure that affect the propagation of photon in the same

way as the periodic potential in a semiconductor crystal affects

the electron motion by defining allowed and forbidden electronic

 energy bands.

Why Photonic crystals ??

Give us a control over photon flow and an even greater

control over material properties.

Quantum dots that provide mode confinement and

density of optical state structures for feedback to take

place

By using 2-D photonic crystals the dimensions of micro-

resonators can be greatly reduced.

Tuning of cavity, by changing refractive index.

Easy to control spontaneous emission, bend light sharply,

trap photons and make devices that provide other

important advances regarding lasers.

Artificially defect states can be introduced .

Design

To evaluate the use of quantum dots within the

active region of laser, a separate confinement

heterostructure laser with 7 layers of quantum

dots is fabricated

Patterned on two crossing waveguides.

The top GaAs waveguide contains a quantum

dots-in-a-well structure, which serves as the

active material for the laser.

The nanocavity, located at the two

waveguide’s intersection, creates a high-Q

optical resonator with the 1-D photonic

crystals acting as highly reflective mirrors.

Confinement and Control

Electrical confinement via the energy

band structure and

Optical confinement is achieved by

means of ridge waveguides and index

contrast.

By removing some of the holes in one of

the photonic crystals, one can control

the direction of the emitted light

Higher powers can be produced by

fabricating nanocavities in arrays.

Coherent coupling of the cavities

generates a single-mode beam from a

small array.

What is special in pc laser

Ultralow threshold (667 A/cm2 for Lateral

cavity PC laser)

High Quality factors (>1x10^6)

Optical as well as electrical pumping (now) can

be used.

Both in the CW and pulsed mode of operation

at a variety of temperatures (@ room temp. in

CW)

Flexibility in shape and size.

PC nanocavities are an ideal platform for low-

power laser sources because strong light-

matter interaction can be obtained.

But

Power ~µw

Applications

As low jitter sources of single, indistinguishable photons in quantum

information processing and related areas.

Low threshold spectroscopy sources and operation of photonic

crystal laser in ambient organic solutions Used to perform

spectroscopic tests on femtoliter volume of analyte and for high

resolution spectroscopy with single molecule sensitivity

Advantageous for optical interconnects which require speed of the

high-speed communications(order of terahertz).

References

http://en.wikipedia.org/wiki/Photonic_crystal

http://web.mit.edu/cbegroup/www/index.html

www.cmu.edu/physics/research/nano-physics/index.html

http://ieeexplore.ieee.org  

http://apl.aip.org/resource/1/applab/v93/i22/p221102_s1

http://www.opticsinfobase.org/view_article.cfm?gotour

http://ab-initio.mit.edu/book/

http://www.stanford.edu/group/nqp/jv_files/papers/hatice-las

er.pdf

Questions ??

Thank you

for your attention !