It’s the process of depositing different material such as silicon dioxide, silicon nitride on substrate. In Oxford Plasma Lab 100, the deposition process is usually carried out at low temperature i.e. less than 400 degrees.

It’s the process of transferring the desired device patterns onto the substrate/sample (Silicon and Silicon Nitride in our case) using light. The Mask Aligner tool MA6/BA6 from Suss Microtec, Germany is capable of giving a minimum feature size down to 1 µm along with user-friendly interface,Also, the DUV lithography tool, similar to above model is available and capable of minimum feature size of 700nm.

Photo masks contain the patterns that get transferred to substrate during photolithography. DWL 66 from Heidelberg Instruments GmbH, Germany is the tool used for direct laser writing of photo masks which has capability to write feature size down to 1 µm.

The Raith 150TWO is an ultra-high resolution electron beam lithography (EBL) tool for nanoscale fabrication. The tool is capable of writing sub-10 nm features. Electron beam energy can be varied from 100 eV to 30 KeV. The system can handle a wide range of samples up to 8-inch wafers. This system has fixed beam moving stage (FBMS) and modulated beam moving stage (MBMS) exposures. It can handle 7-inch masks and perform automatic focus correction. We use the EBL system for the fabrication of photonic integrated circuits on silicon and silicon nitride platforms. In addition, it serves as an invaluable tool for mask writing for the photolithography processes.

This 4-stack horizontal furnace system by SVCS has dedicated tubes, each for thermal oxidation, high temperature annealing, phosphorus and boron diffusion to get n and p-type doping respectively. The furnace tubes can withstand a maximum temperature of 1000°C. The temperature, pressure, process time, gas (Oxygen and purge Nitrogen) ratios and steamer rate (for wet oxidation) can be individually controlled. Loading is mechanical and the oxidation and annealing furnaces can handle processing of a total of 25 four inch wafers each.

It’s the process of depositing thin layer of metals on top of sample for getting contact pads and microheaters. Three types of equipment are available mainly for Thermal Evaporation (HPVT 305G Hydro Pneo Vac Technologies, India), E-beam Evaporation (BOC Edwards Auto 306 and Hind Hi Vac BC 300T), DC and RF Sputtering (Hind High Vac).

It’s the method of separating individual die from each other on the wafer. The equipment used is Advanced Dicing Technology 7100-Provectvs.

This process helps in removing the surface roughness and getting rid of contaminants or subsurface damages. The equipment used is Ultra Pol Ultra Tech Manufacturing Inc., USA.

It’s the process of making interconnects between the IC and the PCB or between multiple ICs. The equipment used is TPT HB10.

The CMP Tribo by Logitech is an industry-standard bench-top Chemical Mechanical Polishing (CMP) system. It handles wafer sizes of up to 4 inches with precision in achieving nanometer-level surface roughness and a dedicated pad conditioning carrier head. In our silicon photonic device fabrication process, we rely on the CMP Tribo for planarizing wafer-scale Silicon Nitride and Silicon-dioxide materials. This crucial step ensures the smooth and uniform surface necessary for the successful development of high-performance silicon photonic devices.

FirstNano Easy Tube 6000 comprises of a 4 stack horizontal chemical vapour deposition (CVD) system with a mechanical loading platform for each furnace tube. The temperature, pressure, process time and gas rates can be individually controlledby a computet running Labview. The system utilizes Nitrogen as the carrier gas and has Oxygen, Dicholorosilane and Ammonia as the feedstock, required for the different furnace tubes each dedicated foe Low Temperature Oxide (LTO), Silicon Nitride (SiN), Polysilicon deposition and Si Nano-rod formation respectively. For Integrated Photonics, we rely on high quality, optical grade SiN layer deposited using this system at low pressure and high temperature. The furnaces can go up to a maximum temperature of 900°C and the wafer boat can support processing of total of 25 four inch wafers simultaneously.

The Olympus laser microscope OLS4000 is helpful in the nanometer level imaging and estimate the surface roughness. The non-contact surface profile measurement (using a low spot size laser source) is non-destructive and allows the accuracy to go to the sub-micron range.

APEX 2043B optical spectrum analyzer offers a wavelength resolution bandwidth of up to 0.04 pm to characterize optical devices. The resolution provided by the device is very beneficial, especially in the case of high Q (narrow bandwidth) micro-ring resonators, for Microwave and Quantum Photonics applications. The device also offers a tunable laser source over the wavelength range of 1520-1630 nm, with the capability to sweep the entire range in few seconds.

The grating coupler setup helps to characterize the fabricated silicon photonic devices. It enables the launch and detection of the laser through the optical fibre with a 6 dB/facet coupling loss. The setup was designed and tested by our group of alumni here at IIT Madras. The launch angle into the on-chip device is 10 degree. The fibre alignment is done manually with the help of a microscope. The setup is isolated from any ambience disturbances through the vibration isolation system of the table.

Programmable Optical Wave Shaper (II-VI 1000A) provides a range of programmable optical filtering and switching options for photonics experiments. It has a Operating Wavelength Range of 1530 nm to 1565 nm. Two units are available in the lab.

Mode Lock Laser (Pritel FFL Series) produces pulses of light of extremely short duration, on the order of picoseconds. It has a Wavelength range of 1530 - 1565 nm and equiped with Pulse Repetition Rate (PRR) of 31.25 MHz, 62.5 MHz, 125 MHz, 250 MHz, 500 MHz, 1 GHz, 5 GHz, and 10 GHz with Internal RF Synthesizer.

The The Lightwave Component Analyzer (LCA) interfaced with Performance Network Analyser (PNA) is used to measure the S-parameters of a microwave photonic link. The LCA comprises inbuilt laser source, intensity modulator and photodetector. The lab is equipped with two Keysight LCAs with the measurement capabilities up to 26.5 GHz and 50 GHz. The Spectrum Analyser inbuilt with the LCA helps to characterize several link parameters such as n^th order output and input intercept points (OIPn, IIPn), spurious free dynamic range (SFDRn) and noise figure.

High Power Erbium Doped Fiber Amplifier amplifies (EDFA) the low input optical signal and gives high optical output power. We have one high power EDFA (Pritel) and one polarization maintaining EDFA (Pritel) with a wavelength range of 1535 nm to 1565 nm and saturated output power greater than 37 dBm.

Highly Coherent Tunable Laser Source (Santec TSL-570) has equiped with a wavelength tuning range of 1480 nm to 1630 nm and max output power of +13 dBm.

A Tunable Laser Source (Apex AP3350A ) has equiped with a Two different module types are available: AP3350A and AP3352A, which covers C-band and L-band respectively. These tunable laser source modules can cover a wavelength range of 82 nm from 1526 nm to 1608 nm.

FormFactor High Precision Silicon Photonics Probe Station is used for a stable optical and electrical characterization of photonic integrated circuits. The equipment can handle 6-inch photonic wafers and is equipped to perform multi-channel DC probing (currently 16) and RF characterization up to 50 GHz.

A near-infrared superconducting nanowire single-photon detector (SNSPD) system (Single Quantum Eos CS-8 channel and efficiency>80%) is being used for quantum photonics experimental studies.

The Holzworth phase noise analyser is used to test the quality of a given RF source by measuring its phase noise. We have the equipment to perform the measurements up to 26.5 GHz.

The modulators are the basic building blocks of any microwave photonic link. We have the Thorlabs intensity and phase modulators that can operate up to 40 GHz.
The drivers are essential for the active control of the bias conditions for an intensity modulator. The lab is equipped with two Thorlabs highly precise modulator drivers which can automatically bias the modulator in QUAD, PEAK and NULL operating conditions.

The Keysight Arbitrary waveform generator (AWG) provides complex signals at 128 GSa/s with 50Ghz analog bandwidth with 2 independent channels. AWG can be used to test modulators and photodetectors with different modulation formats such as PAM4, QPSK, etc. AWG can help in implementing different QKD schemes with its PRBS generator or by feeding the QRNG data to AWG to generate a custom waveform.

The Keysight Infiniium UXR Oscilloscope can sample signals at 256 GSa/s with 10-bit ADC with 50 GHz analog bandwidth in 2 channels. Along with the help of AWG, the Oscilloscope can be used to visualize different modulation formats applied to test modulators. It greatly helps in debugging optical systems such as QKD or optical communication.

A balanced photodetector is used in different types of optical measurements where we need to perform homodyne/heterodyne detection. Operating within the wavelength range of 1525 to 1570 nm, the FINISAR balanced photodetector offers a remarkable radio frequency (RF) bandwidth of 100 GHz. with optical power upto 10 mW at each input port. The device is being used in Quantum Random Number Generation (QRNG) experiments in our lab.

APEX2683A Optical Complex Spectrum Analyzer (OCSA) offers measurement of optical phase along with the power spectrum of signals with bandwidth resolution of 0.8pm, 0.16pm and 0.04 pm @ 100MHz, 20MHz and 5MHz. This device offers the phase measurements for the signals with repetitive rate of 20MHz to 900MHz for different modulation techniques over the wavelength range of 1520-1630 nm. This device has the sweep speed of 1.2nm/sec for the entire wavelength range. Furthermore, it can also display constellation, phase and intensity eye diagrams.