Developing a Photonic Integrated Circuit for Radio-Frequency Interference Cancellation Matthew Chang, Monica Lu, Jenny Sun and Paul R. Prucnal Lightwave Communications Research Lab Princeton University June 15 th, 2015
Sensor networks, especially in urban centers, are highly susceptible to radio-frequency interference In-Range Sensor In-Range Sensor Base Station In-Range Sensor
Remote interference comes from an unknown and presumably independent source In-Range Sensor In-Range Sensor Base Station In-Range Sensor Remote Interference
Co-site interference is generated by co-located transmitters and receivers operating simultaneously; self-interference In-Range Sensor Base Station In-Range Sensor Out-of-range Sensor Out-of-range Sensor In-Range Sensor Remote Interference Co-site Interference
Interference cancellation is needed to protect a sensor network from external RF noise, as well as self-induced noise In-Range Sensor In-Range Sensor Out-of-range Sensor Base Station In-Range Sensor
The rest of this talk Background: Why photonics for interference? Previous work: A discrete modular cancellation system Results: A preliminary Integrated interference cancellation system
Analog signal processing with wide bandwidth and high dynamic range can relax heavy requirements on ADCs Interference Signal of Interest Growth of WiFi Data Rates Power Required Dynamic Range 150 Mb/s 866 Mb/s 54 Mb/s 1 Mb/s Time Requires high-resolution (14-18 bit) ADCs Requires high sampling rate ADCs Background Previous Work Results
Photonics possess several properties that make it a spectacular analog signal processor 1) Wide bandwidth performance 2) Immunity to Electromagnetic Interference (dynamic range) 3) Extremely high precision delay lines (resolution) Power RF Carrier 700 MHz 20 MHz Frequency Background Previous Work Results
Photonics possess several properties that make it a spectacular analog signal processor 1) Wide bandwidth performance 2) Immunity to Electromagnetic Interference (dynamic range) 3) Extremely high precision delay lines (resolution) Power RF Carrier 700 MHz Optical Carrier 193 THz 20 MHz Frequency Optics treats RF wireless signals as narrowband Therefore, it is indifferent to channel bandwidths or center frequency Background Previous Work Results
The rest of this talk Background: Why photonics for interference cancellation? Previous work: A discrete modular cancellation system Results: A preliminary Integrated interference cancellation system
An optical interference cancellation system was first demonstrated using fiber-optics and discrete optics Radio Communication Transceiver PA = Pre-amplifier LNA = Low-noise amplifier RX = Receiver TX = Transmitter Background Previous Work Results
The optical cancellation system uses a set of variable optical attenuators and delay lines to emulate channel response Radio Communication Transceiver PA = Pre-amplifier LNA = Low-noise amplifier RX = Receiver TX = Transmitter Background Previous Work Results
The discrete interference cancellation demonstrated almost 40 db of cancellation over 1 GHz. Nearly 40 db over 1 GHz RF bandwidth 45 db over 100 MHz RF bandwidth Fluctuations in cancellation are due to remaining RF components in circuit Background Previous Work Results
The optical system can operate over a wide range of RF bandwidths, and the signal of interest is unharmed Background Previous Work Results
The system is also independent of modulation format Single-tone signal of interest 50 MHz wide FM jammer signal Background Previous Work Results
The rest of this talk Background: Why photonics for interference? Previous work: A discrete modular cancellation system Results: A preliminary Integrated interference cancellation system
A photonic integrated circuit (PIC) will greatly reduce size, weight, and power, AND open the door to mobile applications Advantages to a PIC: Size, weight, power Robust to mechanical shock, vibrations, temperature effects Volume manufacturing Applications which require mobility Disadvantages to a PIC: Performance not as optimized Manufacturing readiness Background Previous Work Results
The interference cancellation PIC is monolithically integrated, so that no light ever has to enter or leave the chip Key Design Features: The chip is self-contained. Electrical in and electrical out All elements are electronically controlled Fabrication process ensures complimentary components are wellmatched Background Previous Work Results
The chip is fabricated from InP laser-diode material (1550 nm) so optical generation and detection can be performed on-chip 2.5 mm Silicon Submount InP PIC Electrical Probe
The Integrated Prototype has nearly all the functions of the discrete system except time-delaying
The Integrated Prototype has nearly all the functions of the discrete system except time-delaying Monolithic Laser An on-chip optical source
The Integrated Prototype has nearly all the functions of the discrete system except time-delaying Modulator Electrical-Optical Conversion
The Integrated Prototype has nearly all the functions of the discrete system except time-delaying Attenuator To perform amplitude matching
The Integrated Prototype has nearly all the functions of the discrete system except time-delaying Photodetector On-chip optical-electrical conversion
Proof of concept cancellation is demonstrated using a balanced photodetector configuration DC Bias Bias T TIA+ Interferer 50/50 Splitter V bias + V bias - Output Bias T TIA- RF Output DC Bias Background Previous Work Results
The interference cancellation PIC is used to cancel AM interference 125 mv No Cancellation V att = 1.32 V V att = 1.35 V V att = 1.37 V V att = 1.42 V Background Previous Work Results
With basic functionality demonstrated, there are many paths for future work Area Improvement Operation Functionality Bandwidth Ion implantation to prevent crosscurrents from affecting device operation Include slow and fast light phase-shifting to improve signal matching Hybrid integrate a commercial highfrequency transimpedance amplifier
Questions? E-mail: mpchang@princeton.edu Thank you to: NSF ERC MIRTHE Prof. Claire Gmachl s Group Former and current REU students The Lightwave Labmates