IIIV/siliconphotonicsfor+microwave+photonics · PHOTONICSR ESEARCHG ROUP) 1 PHOTONICS RESEARCH GROUP IIIV/siliconphotonicsfor+microwave+photonics + Thecaseofanelectrophotonicfrequencyconverter

PHOTONICS RESEARCH GROUP 1

PHOTONICS RESEARCH GROUP

III-‐V/silicon photonics for microwave photonics

The case of an electro-‐photonic frequency converter

G. Roelkens1, W. Bogaerts1, D. Van Thourhout1, G. MorCer1, R. Baets1, E. Bente2, L. Thomassen3

1 Photonics Research Group, Ghent University – imec

2 Eindhoven University of Technology, Netherlands

3 Antwerp Space, Belgium

2 PHOTONICS RESEARCH GROUP

Outline

•  Silicon photonics

•  III-‐V/Silicon photonics

•  Electro-‐photonic frequency converter as case for MWP applicaCons


Silicon photonics

High index contrast waveguide structures • Size reduction of photonic integrated circuits • CMOS fabrication technology (200mm/300mm) • High performance passive devices • High performance Ge photodetectors • High performance electro-optic devices

PHOTONICS RESEARCH GROUP 4 PHOTONICS RESEARCH GROUP

Silicon wire waveguides

220nm

460nm


Mach-Zehnders

Ring resonators

Arrayed waveguide gratings

Bragg reflectors

Echelle gratings

Spectral filters


-10 -5 0 5 10

-15

-10

-5

0

1.85pm

Data ring 1 Data ring 2 Lorentzian fit ring 1 Lorentzian fit ring 2

Nor

mal

ized

resp

onse

(dB

)

Wavelenght (pm)

3.05pm

Example: ring resonators with intrinsic Q of 8*105

700nm

150nm 70nm

Results: Ring 1: Q = 508k, Finesse = 1340 Ring 2: Q = 831k, Finesse = 1067

(R=25µm) (R=50µm)

Linewidth: 200-300MHz

Microwave photonics filtering


High speed opIcal modulators

Based on carrier depleCon in a lateral p-‐i-‐n diode => phase change

P++ P N N++

V

P N P+ N+ N+ P+ N

cathode anode -- ++ -- ++ -- ++

- + - + - +

Vertical PN junction Interdigitated PN junction

Doping patterns to enhance the modulation efficiency, linearity,…



5 10 15 20 25 30 35 40-9

-6

-3

0

f (GHz)

Freq

uenc

y re

spon

se (d

B)

measurementtheory

•  f3dB of |S21| is 15 GHz for 3 mm traveling wave electrode; •  f3dB of |S21| is 5.5 GHz for 1.5 mm lumped electrode.

R L

Cair Cbox

Csub

Gsub

CssubCsub1

Cdep

ZSi

Cvia Cmetal

Air Sub BoxPMD_right Wg_rightWg_left

RSi

Csslab

Cslab GslabCslab1CPMD_r

•  conformal mapping •  partial capacitance technique

Air

Air

SiO 2

Si Sub

PMD

W G G W g W g

n ++ Si p Si n Si i Si W via

p + W dep

H metal

p ++ Si H via

H box

H sub

H slab W rib

Signal Ground Ground

n +

h 1

h 4 h 3

h 2

Bandwidth of the traveling wave design is determined by: •  impedance match； •  RF aLenuaIon; •  velocity match between RF and lightwave.

Reverse bias= -4 V



•  Currently most focus is on digital applicaCons

•  Literature on linear modulaCon in silicon is emerging [1] [2]

[1] A Silicon modulator enabling RF over fiber for 802.11 OFDM signals, JSTQE 16(1), p. 141 (2010) [2] Broadband linearized silicon modulator, Opt. Expr. 19(5), p. 4485 (2011) (figure b)


Ge photodetectors

Process is currently being developed in imec •  First results: 10Gbit/s operation •  100GHz bandwidth in a single PD and 10Gb/s operation

in a balanced configuration has been shown (process: CEA-LETI)

[1] Zero-‐bias 40Gbps Ge waveguide photodetector on Si Opt Expr 20(2), p.1096-‐1103

!


High-‐efficiency fiber-‐to-‐chip graIng couplers

-‐5.0

-‐4.5

-‐4.0

-‐3.5

-‐3.0

-‐2.5

-‐2.0

-‐1.5

-‐1.0

-‐0.5

0.0

1510 1520 1530 1540 1550 1560 1570

Insertion loss fo

r 1 cou

pler [d

B]

Wavelength [nm]2µm SiO2

silicon substrate

220nm Si

Thicker teeth: poly-Si overlay

-1.6dB coupling efficiency


Automated wafer-‐scale measurement set-‐up

GraCng couplers enable wafer-‐scale tesCng of the photonic integrated circuits


Outline



•  Electro-‐photonic frequency converter as case for MWP applicaCons


Silicon ++ photonics

Integration of light sources and optical amplifiers • Completes the set of building blocks • Heterogeneous integration of III-V semiconductors

•  state-of-the art electrically injected light sources •  Large design space and many technological choices


III-‐V integraIon on SOI

Song e.a. OE 17, 14063-14068 (2009)

Hybrid / flip chip integration

Junesand e.a., IPRM 2009 pp. 59

III-V on Si heteroepitaxy Wafer bonding

Roelkens e.a., LPR 2010


III-‐V integraIon on SOI

An adhesive bonding layer (DVS-‐BCB polymer) is used

-‐ Large range of bonding layer thicknesses (20nm to 2µm) -‐ Requirements on wafer quality are relaxed

(a) (b)

(e) (f)

(c)

(d)

SOI-wafer Planarization Bonding

Substrate Removal Pattern definition III-V processing


III-‐V integraIon on SOI Both mulCple die-‐to-‐wafer bonding and full wafer bonding (2inch)

30+/-5nm bonding layer


Example: III-‐V/Si extended cavity laser

From full confinement in III-‐V to full confinement in SOI

I II III IV

Fundamental mode in different cross-sections (BCB thickness=80nm)


Example: opIcal amplifier based on same technology

!


Example: integraIon of tunable laser with modulator

III-‐V/silicon tunable laser realized, co-‐integrated with silicon electro-‐opCc modulator, based on ring resonator feedback


Y. Tang, J. Peters, J. Bowers, Over 67GHz bandwidth hybrid silicon electroabsorpCon modulator, Opt. Expr. 20(10), p. 11529 (2012)

DemonstraIons from other labs: hybrid EA modulators


Outline



•  Electro-‐photonic frequency converter as case for MWP applicaIons


Concept of the electro-photonic frequency converter (EPFC) Implement functionality on III-V on silicon platform:

•  III-V on silicon modelocked laser •  Silicon EO modulator or III-V EA modulator •  Silicon or III-V balanced detector pair

Proposed implementaIon


Proposed implementaIon

Fundamental rep rate or higher harmonic

Push pull operation to avoid IMD2

External reference necessary to reach phase-noise specs


Proposed implementaIon: Mode-‐locked laser

Sat. Abs. Gain region

Long delay in low loss silicon WG: improved phase

noise


Value of integraIon for frequency downconverter

Electro-‐photonic frequency conversion allows for: –  Broad bandwidth –  Flexibility –  Re-‐configurability

But also increased scalability at lower mass, volume and power consumpCon.

Documents

IIIV/siliconphotonicsfor+microwave+photonics · PHOTONICSR ESEARCHG ROUP) 1 PHOTONICS RESEARCH GROUP IIIV/siliconphotonicsfor+microwave+photonics + Thecaseofanelectrophotonicfrequencyconverter