Herb Kroemer Optical Patents:The alpha and the omega…

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Kroemer SymposiumJohn BowersMay 20, 2013

Herb’s First Optical Patent: Double Heterostructure Laser

Filed: 1963Issued: 1967Expired: 1985

Patent 3,309,553

Double Heterostructure Laser Diode: The first cw semiconductor laser

Izuo Hayashi (left) and Morton Panish (1971) at Bell Labs were able to design the first semiconductor laser that operated continuously at room temperature. The need for semiconductor heterostructures for efficient laser diode operation was put forward by Herbert Kroemer. (Reprinted with permission of Alcatel–Lucent USA Inc.)

M. B. Panish et al. APL 16(8), 1970

400x

0 0.4 0.8 1.2 1.60

5E+017

1E+018

1.5E+018

2E+018

Distance from surface (mm)El

ectro

n C

once

ntra

tion

(cm

-2)

Carrier confinement

Heterojunction Homojunction

Higher optical losses

0 0.4 0.8 1.2 1.60

5E+017

1E+018

1.5E+018

2E+018

Distance from surface (mm)

Elec

tron

Con

cent

ratio

n (c

m-2

)

Heterojunction Homojunction

Index profile

Intensity profile

1%

10%

1 exp Cd n n : the difference in the reflective indexd : the thickness of the active layer, C : Constant

Optical confinement

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How Important is this Invention?

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How Important is this Invention?

About $4B annually

Laser Focus World Jan. 2013

All commercial diode lasers use double heterostructures

Herb’s patent runs out

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Herb’s second optical patent

Light-emitting structures in silicon are more attractive from a fabrication standpoint…light generation in silicon is an inefficient process…

Herb’s Latest Optical Patent: Optical Isolator

Hybrid Silicon Ring Isolator

1551.0 1551.1 1551.2 1551.3 1551.4-60

-58

-56

-54

-52

-50

-48

-46

Tran

smis

sion

(dB

m)

Wavelength (nm)

inward-direction magnetic field outward-direction magnetic field

Tien et al. “Silicon ring isolators with bonded nonreciprocal magneto-optic garnet” Optics Express (2011).

First experiment Optimized design

Herb: Thank you!

• For your insights• For setting high standards in research, and faculty

and students recruiting• For tolerating my research on hybrid III-V silicon

photonics…the gain is in the III-V after all, not like those MIT guys…and you were 45 years ahead anyway.

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