E/O and O/E devices, the collaboration with the industry:E/O and O/E devices, the collaboration with the industry:

E/O and O/E devices, the IRA link:E/O and O/E devices, the IRA link:

Optical connectors:Optical connectors:Optical fibre cable:Optical fibre cable:

Analogue optical links experiences in the framework of the SKA/BEST activities

Federico Perini

INAF-IRA (I)

Custom product: optimised specs (<1GHz) and mechanical RX housing.

TXRX

Power Supply, single positive = (12-15)Volt@75mA Passive optical receiver

APC (Angle Polished Connector)

has RL>70dB → increases the

performance of the RoF link (Dynamic

and NF)

Motivation:

Necessity to bring the signal from the BEST Front End, on the antenna focal lines, to the central processing room.

Which solution: Coax or Optical cables? Analogue or Digital links?

Cost and Reliability prediction analysis of the whole receiver chain indicated the analogue optical link as the best solution, so:

Which kind of fibre?

Which kind of optical connectors?

What E/O and O/E devices?

Motivation:

Necessity to bring the signal from the BEST Front End, on the antenna focal lines, to the central processing room.

Which solution: Coax or Optical cables? Analogue or Digital links?

Cost and Reliability prediction analysis of the whole receiver chain indicated the analogue optical link as the best solution, so:

Which kind of fibre?

Which kind of optical connectors?

What E/O and O/E devices?

Monomode loose fibre cable are the best in term of insertion

loss and phase stability vs temperature and bending

DIN best on moving antennas

SC: best for fixed indoor applications with high integration

SC could be the best compromise

Laser DFB 1310nm MQWSPV4260 Sumitomo

RIN = -155dB/Hz= 0,2 mW/mA

Ith = 8mA

PIN PhotodiodeSPV3313 Sumitomo

= 0,9 mA/mWIdark = 1nA

fmax = 2GHz

Selected devices after market survey

Direct optical modulation and detection: simpler, cheaper and high performances up to some GHz.

TX-O features:

Resistive matching APD circuit through the integrated monitor photodiode Slow power-on circuit

RX-O features:

Direct detection by PIN photodiode

Passive optical receiver(no transimpedance amplifier)

First custom prototype under evaluation: prliminary results!

Double power Supply =+/- 5.8V

Amplified link: transmipedence amplifier in the RX-O

IIP3>+32dBm

IIP3>+20dBm

Ripple, induced by TX-O,

detected on the transit of CAS-A

with a single BEST-1 RX!

Interferometer 1-4

Sideral time (sec)

Complex correlation

fringes, about 1 hour

acquisition, CAS-A source

Quasi perfect match between simulated and

measured fringes (no ripple is

reconisable)

Still to investigate the

effect on a beamformer

Analisys of the ripple impact on

real observations

Lab. ripple test with an automatic

measurement system