ASPICs for High Energy Physics Applications Deepak Gajanana, Martin van Beuzekom Nikhef (National Institute for Subatomic Physics), Amsterdam Xaveer Leijtens Eindhoven University of Technology, Eindhoven 4-06-2014 TIPP 2014 DGB et al.

Contents Introduction Generic Integration Technology (InP) Example photonic ICs Application in HEP experiments “An Application Specific Photonic Integrated Circuit integrates multiple optical components like sources, detectors, modulators etc. to save area, cost, power and add more functionality.” Explain what an ASPIC is… Similar to cmos ic And is following the same trend as cmos ic did in late 70’s and 80’s 4-06-2014 TIPP 2014 DGB et al.

Scanning Electron Microscope (SEM) Optical Waveguide InGaAsP (1.3) InP 2 m 0.6 m Most basic building block Why InP Scanning Electron Microscope (SEM) photograph Simulated mode distribution Materials could be Si, Binary, Ternary and Quaternary semiconductors. Indium Phosphide (InP) in combination with InGaAsP has advantages of making light sources, detectors and other circuits at 1550 nm (3rd generation telecom wavelength). 4-06-2014 TIPP 2014 DGB et al.

Waveguide fabrication process InP InGaAsP InP-substrate 4-06-2014 TIPP 2014 DGB et al.

Optical Waveguide 75 μm human hair 4-06-2014 TIPP 2014 DGB et al.

Arrayed Waveguide Grating (AWG) COBRA 1988 Smit, El. Lett, 1988 4-06-2014 TIPP 2014 DGB et al.

MMI (Multi Mode Interference) Couplers Geometry of MMI-couplers Simulated pattern Experimentally imaged pattern Acts as power splitter/combiner. Various power ratios possible. 4-06-2014 TIPP 2014 DGB et al.

Mach Zehnder Switch Electric field changes the refractive index and hence the phase change of the optical wave 4-06-2014 TIPP 2014 DGB et al.

Photonic Integration with basic building blocks 4-06-2014 TIPP 2014 DGB et al.

Moore’s law for InP based PICs AWG-based devices 4-06-2014 TIPP 2014 DGB et al.

Moore’s law for InP based PICs Steenbergen 8x20 GHz WDM receiver PTL, 1996 4-06-2014 TIPP 2014 DGB et al.

Moore’s law for InP based PICs Infinira 10x10 Gb/s WDM TRX 2005, 51 components Moore’s law for InP based PICs 4-06-2014 TIPP 2014 DGB et al.

Moore’s law for InP based PICs Nicholes, MOTOR chip, OFC 2009, UCSB, 145 components Moore’s law for InP based PICs 4-06-2014 TIPP 2014 DGB et al.

What Next? Commercial Advantages : Integrating more functionality, reducing size and reducing cost 4-06-2014 TIPP 2014 DGB et al.

Photonic IC Generic Integration platform optical amplifier phase modulator Phase Amplitude polarization converter Polarization waveguide Passive Application Photonics Design Manual A designer Powerful circuit simulation tools Powerful layout tools Multi-project wafer Designs from designers using the same platform New design Wafer fab Device back to users 4-06-2014 TIPP 2014 DGB et al.

History repeats itself… Silicon electronic ICs 1979 Indium phosphide photonic ICs 2012 MPC79, Lynn Conway 4-06-2014 TIPP 2014 DGB et al.

Examples of ASPICs and applications 4-06-2014 TIPP 2014 DGB et al.

External modulation technique Modulators form the heart of the external modulation technique. Optical modulator Continuous wave injection laser Photo diode Amplification Digital read-out Chip Modulation Data acquisition & processing CW Laser Data Two types of modulators : Electro optic modulators, Absorptive modulators. MZ interferometer works on electro optic effects. InP Metal Data arm Databar arm Laser input Light output Mach Zehnder (MZ) Modulator 4-06-2014 TIPP 2014 DGB et al.

KM3NeT Detector concept KM3NeT is a cubic kilometer neutrino telescope to be installed in the Mediterranean sea. For more information : www.km3net.org High density data readout in remote submarine conditions. Savings in area, cost and power motivate innovation, research and development of ASPICs. The detection of the Cherenkov light must proceed on a single‐photon level for reconstructing the neutrino direction and energy. The neutrino telescope is composed of a number of vertical structures (“Detection Units”), which are anchored to the sea bed and kept vertical by one or several buoys at their top. 320m 4-06-2014 TIPP 2014 DGB et al.

Concept for 80 Channels with Overlay DWDM* @1.25 Gbps (Downstream Data) 1:20 1 MOD + Drivers Lasers C - Band 20 x 2 1:4 λ1 C λ82 LiNbO3 A1 DOM D2 80 λC CW 50/50 C - Band C λ1-80 A2 λ20 200 GHz DWDM DU-String OTDR Timing mode SMA LiNbO3 C2 SMA VOA on/off C1 Junction Box λ1 80 λC @1.25 Gbps (Upstream Data) λ1 50-200 GHz APD C2 C2 D1 A3 C-Band λ80 100 km Secondary Junction Box Shore station λ1-80 C-Band 1528-1568 nm L-Band 1568-1610 nm 200 GHz 200 GHz λ82 50 GHz PIN …. …. λC REAM 2xCu DOM λC1-80 λC1,5…80 + λC 82 *R&D on high density data readout. Explored as an option - Not used in the project presently. 4-06-2014 TIPP 2014 DGB et al.

InP based Colorless transceiver for KM3NeT Continuous wave light (one of the 20 wavelengths separated at 200 GHz ) is separated from the slow control data. The slow control data is detected by the photodiode and provided to the electronics. The data from the sensors (effective data rate ~1.25 Gbps upstream) modulates the CW light and is reflected. Aim is to integrate the building blocks (AWG, Modulator and PD) on a single die. AWG Reflective Modulator 1 x 21 21 x 1 λx λ1 PD DOM Electrical Domain 20λ λ1+λx λx can be any of the 20 wavelengths REAM 2xCu DOM PIN λC λ82 will replace 4-06-2014 TIPP 2014 DGB et al.

InP based Colorless transceiver for KM3NeT Reflective circuit AWG Reflective Modulator 1 x 21 λx λ1 PD DOM Electrical Domain λ1+λx λx can be any of the 20 wavelengths SOA Test structures Transmissive circuit AWG Transmissive Modulator 1 x 21 λx λ1 PD DOM Electrical Domain λ1+λx λx can be any of the 20 wavelengths SOA MMI AWGs channel spacing is dependent also on processing. With a loop back architecture, we remove the process variations on the AWG. Transmissive architecture can be used for testing purposes. 4-06-2014 TIPP 2014 DGB et al.

ASPICs for High Energy Physics Experiments Modulators form the heart of the external modulation technique. Little is known about radiation hardness of (InP) modulators. Ultimate goal : application at inner detectors at HL LHC. Optical modulator Continuous wave injection laser Photo diode Amplification Digital read-out Chip Modulation Detector – High Radiation environment Low radiation Data acquisition & processing CW Laser Data Two types of modulators : Electro optic modulators, Absorptive modulators. MZ interferometer works on electro optic effects. InP Metal Data arm Databar arm Laser input Light output Mach Zehnder (MZ) Modulator 4-06-2014 TIPP 2014 DGB et al.

Beam Test of InP based MZ modulators Samples mounted in a shuttle that moves in and out of the 24 GeV/c proton beam at CERN to 1E12, 1E13, 1E14 and 1E15 p/cm2. Vertex detectors at HL-LHC require a radiation hardness ~ 1E16 p/cm2. The sample contains 22 modulators and measures 14mm × 4 mm Submount dimensions : 48 mm × 42 mm 4-06-2014 TIPP 2014 DGB et al.

Measurements of photonic chips Measurements need precision alignment of chips and fibers. Lensed fibers are used to couple and collect light. Alignment of fibers are done manually using manipulators. Lensed fiber (9 u core) to be aligned to a 2 u wide 1u high waveguide. Bond wire 4-06-2014 TIPP 2014 DGB et al.

A Sample measurement Input power = + 6dBm @ 1550nm Y axis – Power (dBm) measured at the output. X axis – Voltage scan on one of the arms of the modulator. Imbalance Data arm Laser input Light output PD Databar arm InP Metal 4-06-2014 TIPP 2014 DGB et al.

WDM Modulator in the COBRA6 run MZ (DE)MUX SOA MZ modulators: 2 mm phase sections Two 2×5 AWGs: Δ𝜆=400 GHz FSR=2400 GHz Amplifiers: small: modulation large: gain Test structures: separate building blocks DC and RF electrical contacts WDM modulator MZ modulators SOA Waveguide facet Test SOA Test Modulator Test AWG 4-06-2014 TIPP 2014 DGB et al.

Preliminary Measurement results On Chip InP Metal TMm arm TMp arm Laser input Light output Optical power meter CS = 400 GHz FSR = 2400 GHz Crosstalk = 16 dB (DE)MUX EDFA Optical Spectrum Analyzer 4-06-2014 TIPP 2014 DGB et al.

Conclusions and Future Photonic Integration is in it’s nascent stages and holds a ‘bright’ future. Physics experiments can benefit from custom ASPICs. Smaller, low power, more functionality, cheaper for large quantities Generic Photonic Integration platform and access to MPW runs makes it easier for designing ASPICs for High Energy Physics. Lot to be designed and measured, long way to go… 4-06-2014 TIPP 2014 DGB et al.

Arrayed Waveguide Grating Vellekoop, 4-channel demux, JLT, 1991 4-06-2014 TIPP 2014 DGB et al.

Moore’s law for InP based PICs Herben, 4-channel 2x2 OXC, PTL, 1999 4-06-2014 TIPP 2014 DGB et al.

Moore’s law for InP based PICs 4-06-2014 TIPP 2014 DGB et al.

Generic Integration Technology Waveguides are ~ 2um wide and a um high Phase change is brought by applying an electric field and changing the refractive index Minimum resolution in COBRA process ~ 100 nm SOA (gain sections) Shallow etched waveguide Deep etched waveguide Electrical isolation section Phase modulator Photonic integration taking the electronic integration way. 4-06-2014 TIPP 2014 DGB et al.

Examples of Non-telecom Application Areas Compact Frequency-comb generators for metrology Skin Analysis Readout units for fibre strain sensors Optical Coherence Tomography 4-06-2014 TIPP 2014 DGB et al.

OPA02_02 – Colorless transceiver Integration of such (de-)multiplexers, modulators and photodiode in a single die saves cost and area. Reflective and transmissive (for test purposes) configurations included. Aimed as an alternative for the REAM solution. Polarization dependence is a potential problem. 4-06-2014 TIPP 2014 DGB et al.

Irradiated and Non-Irradiated Sample measurements Input power = + 6dBm @ 1550nm Y axis – Power (dBm) measured at the output. X axis – Voltage scan on one of the arms of the modulator. Imbalance Data arm Laser input Light output PD Databar arm InP Metal Attenuation at zero bias = 7 dB No phase behaviour! 4-06-2014 TIPP 2014 DGB et al.

Modulators Two main types of modulators Absorptive modulators Absorption coefficient of the material in the modulator can be manipulated by the Franz-Keldysh effect (bulk semiconductors), the Quantum-confined Stark effect (InP QW, QDs), excitonic absorption, changes of Fermi level, or changes of free carrier concentration (bulk Si, InP). Refractive modulators. make use of an electro-optic effect like Pockels effect (linear EO effect) (LiNbO3, GaAs), Kerr effect (quadratic EO effect) (Nitrobenzene) to change the refractive index. 4-06-2014 TIPP 2014 DGB et al.

SP08-2-3 SMART Photonics Run AWG Reflective Modulator 1 x 21 λx λ1 PD DOM Electrical Domain λ1+λx λx can be any of the 20 wavelengths SOA AWGs channel spacing is dependent also on processing. With a loop back architecture, we remove the process variations on the AWG. 4-06-2014 TIPP 2014 DGB et al.

SP08-2-3 SMART Photonics Run AWG Transmissive Modulator 1 x 21 λx λ1 PD DOM Electrical Domain λ1+λx λx can be any of the 20 wavelengths SOA MMI Transmissive architecture can be used for testing purposes. 4-06-2014 TIPP 2014 DGB et al.

Submount design Custom PCBs: Mount and handle the non-packaged optical circuits. Bias the circuits during irradiation to imitate the operating conditions. PCB Backside of Al piece Peltier / TEC element Al piece for heat dissipation 4-06-2014 TIPP 2014 DGB et al.

Packaging of Photonic chips - example Linkra packaging proposal of the TxRx chip 4-06-2014 TIPP 2014 DGB et al.

Commercial Operation Cost of an MPW: 50-100 k€ With 10 designs: 5-10 k € per design For this money you get ~20 chips Cost for your chips: <10 €/mm2 for small series In PARADIGM there is access for external users: Your application? 4-06-2014 TIPP 2014 DGB et al.