1.5 μm VCSEL developed with half the DBRs of conventional VCSELs

Princeton Optronics secures US$25m for high-power tunable laser After being founded in 1993 by

broadly tunable laser, along

Princeton

president

with the continued

established

its roots in RF-

microwave

engineering

Chuni Ghosh from

Sarnoff as the RF-microwavefocused Princeton

of its manufacturing

Electronic

Systems but re-named in 2000, tunable laser developer Prlncetoll

optronics

(Princeton,

facility

Ghosh says “PowerSweep effectively

Illc

2000

a US$25m 2nd round of financby Investor Growth

stability and

ness Park,Yarnton, devel-

Controlled

Oscillator

Synthesizer

product

based on lowcost

and

optical amplifiers

lines.The

organizations

such as the US

government’s

Department

Capital, and including invest-

Over the last year the company

DARPA and NASA to establish

ments from Technology

has developed high-power

expertise

VCSELs, MEMS and RF technolo-

fiber-optic

gies.The

nologies

investors

Novak Biddle and

Defense, Department

company will also fur-

Intel Capital).This

will fund the

ther scale operations

final development

stage of its

of its 12.5 Gb/s receiver and

research

modulator

contracts.

PowerSweep

2000 high-power,

in support

driver product

lines.

of Energy,

in high-performance and microwave of numerous

Most of its 45 existing staff site in Strathclyde,

Scotland, but it is hoping to expand to over 100 in a year,

SBI

dronovich

of Strathclyde

of Maryland have made a

and development

Tim Bestwick

The insulating

distributed

confines

con-

Press as vp marketing and John M&a&an

buried oxide

the charge carriers

1.55 pm VCSEL with a

sists of a single 70 mn-thick

the laser active region, while

layer with the composition

the reduced

single-

applications). “Most applications

the oxide confines

This layer improves VCSEL

mode fibre telecoms

to date have

efficiency

through the selective

oxidation

formation

refractive

index of

the laser

on multi-mode

process

has

no effect on the series resist-

opti-

Most VCSELs contain distrib

I

(DBRs)

made from GaInAsP/lnP (which

?

p-DBR AIGalnAshP iOp tion layer

Oxidation continement AlnAsP

reflectivity).

Ill-k

Cladding layers GaInAsP

are there-

to

of I6 pairs of

consists

DBR

of 22 pairs of

AlGaInAs/InP layers). Christou

said: “We have used a

number

which reduces

the

of mirror pairs needed

to achieve

the quarter-wave-

length thicknesses

required

for

reflection.”

The unstrained

multi-

MQW structure

was grown using molecular

n-DBR AIGalnAshP

beam epitaxy.The operates

but contains

DBR layers as conventional

consists

near-perfect

well (MQW) active

only about half the number VCSELs.

Unstrained MQW GalnPAs

of two

matched

index of 0.63.The

binations

41 pairs (for the same

an InP substrate)

in

new ratio for the material com-

and AlGaInAs/AlInAs which

layer (both lattice

refractive

(which

pairs for a 99.9% reflectivity)

quantum

and k@

AlGaInAs/lnP layers) and

require the growth of 50-layer

DBRs and an unstrained

layers of

99.9% for the bottom

IT0 electrode

The device consists

of alternating

mirror reflectivities (which

Schematic VCSEL structure

Christou.

requires

consist

fore 97% for the top DBR

cal fibres:’ said Professor Aris

uted Bragg reflectors

The two DBR structures

These have a difference

centred on 850 nm VCSELs operating

device,” said Christou.

Ab.05Ga0.42’“o.53As

“This oxidization

of a 7 pm-

as vp manufacturing.

ante or the speed of the in

emission.

diameter aperture.

and Goldman Sachs.

Kamelian has also appointed Bob

power output of over 1 mW at 20°C (targeting

with &20m of

venture capital funding from 3i,

The lowest layer of the p-type Bragg reflector

Uni-

versity, CEO Paul May and COO

15 pm VCSEL developed with half tie DBRs of conventional VCSELs researchers

last

Summer by Professor Ivan An-

Lightspeed

University

(SOAs).

Kamelian was established

tech-

through the successful

execution

by end-200 1

have already moved from its previous

of

VCSEL and MEMS technology.”

Partners LP and first-round

UK for the

volume production

of its InP-based semiconductor

Capital and St Paul Venture Venture

Opt0 start-up KameIIan is setting up a fab in Oxford Busi-

company worked closely with

several additional customer requirements..

Systems

opment of its Voltage

addresses the call for

grated wavelength

Electronic

through the commercial

high power, broad tuning, inte-

NJ, USA) has closed

ing (celed

expansion

Kamelian moves into production fab

device

at 1.526 v

and con-

sists of eight 6 run-thick wells

of Pictured - The structure of the University of Mary/and’s only half as many DBR layers as conventional VCSELs.

REVIEW THE ADVANCED SEMICONDUCTOR MAGAZINE VOLq

- NO 8 - October 2001

VCSEL, which has

separated by seven 9 run-thick barrler layers.