Conclusions

Dynamic control of optical modes in 2D photonic crystal nanocavitiesJeremy Upham*, Yoshinori Tanaka, Takashi Asano and Susumu Noda

Department of Electronic Science and Engineering, Kyoto University*Presently at: Department of Physics, University of Ottawa

Dynamic control over optical modes in the nanocavity permitsthe clear release of the 4 ps pulse up to 332 ps after capture.

Free carrier excitation enables this dynamic control, but also limits performance because of absorption.

Further optimization of the optical modes may reduce carrier losses.

Y. Tanaka, J. Upham, T. Nagashima, T. Sugiya, T. Asano, S. Noda., Nature Mater. 6 (2007). J. Upham, Y. Tanaka, T. Asano, S. Noda., Opt. Express 16 (2008).J.Upham, Y. Tanaka, Y. Kawamoto, Y. Sato, T.Nakamura, B.S. Song, T. Asano, S. Noda., Opt. Express 19 (2011)

References

Dynamic Pulse Capture and Release

The vertical emission from the cavity is proportional to the cavity energy at that moment. We can observe its time-evolution to determine the cavity behaviour.

Control pulse dynamicallychanges cavity from low Q state to high Q.

-20 0 20 40 60Time [ps]

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Inte

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.u.] Low Q fitting: 2,500

High Q fitting: 23,100

Control pulse irradiated

Pulse Capture

2nd control pulse lowers Q again and sends light back down waveguide at a time of our choosing.

Pulse Release

Catch a 4ps pulse with a 19 ps cavity lifetime

Can release captured light on-demand

-20 0 20 40 60Time [ps]

Catch only

Release pulse irradiated 7, 20 & 30 ps after capture

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Q Control MethodTotal Q determined by vertical coupling (QV) and in-plane coupling (Qin)

inQQQ

111

vTotal

cos1)(

orgin

in

QQ

The two optical paths in waveguide give Qin phase dependence

Control pulses

Hetero-interface mirror

1

2TQV: coupling to

free-space modes

Qin: coupling to waveguide

Input pulse

Simulated cavity energy response to dynamic Q control

Photonic crystal nanocavities are well adapted to spatially confining confining photons, exhibiting resonant quality (Q) factors as high as several million and wavelength-order dimensions.

Introduction

Low Q

Introduce a second waveguide to now have two controllable ports for manipulating access to the cavity

This allows for a multi-step process to capture light in the cavity for some time, then release it onwards.

Double Waveguide Model

Time

In-p

lane

Q

QUQL

Control 1 Control 2

As signal enters cavity,Dynamically increase QL

to capture light

Choose when to lower QU,,Light preferentially escapes via upper waveguide

QL

QU

Control pulse 1

Control pulse 2

Input pulse

Hetero-interfacemirror

Hetero-interfacemirror

0 100 200 300Time [ps]

Released After 52 ps

Released after 332 ps

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Pulse release on-demand

Observing Forward Release

Same behaviour as the cavity energy in single waveguide device

Clearly visible released pulse

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Vertical Emission (Cavity Energy) Output Port

0 100 200Time [ps]

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Static initialconditions

0 100 200Time [ps]

Catch

Release

Catch

Catch

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Release

Release

HeteroInterface

HeteroInterface

a2

393 nm a1

408 nm

~110a1

~110a1

L3 shifted edge cavityQv ~100,000QU

orig, QLorig ~ 7,000

Released pulse

Released pulse

Couple pulse into nanocavity

Rapidly increase QCapture light in nanocavity with long photon lifetime

Rapidly decrease QRelease pulse on demand

Temporal control of Q necessary to effectively couple optical pulses.

Lens

Pol. Ctrlr

Polarizer

OFA

Pinhole

Lens

Control Pulse(2nd Harmonic)

Dichroic Mirror

Variable delay

Phase modulation,Variable delay

OFA1550 nm

Pulse Laser(4ps, 1MHz)

Lock-in Amp

4 ps pulse at λ=1550 nm couples to nanocavity

775 nm, 4 ps pulsesCarrier-plasma effect lowers n , shifts by