Sandia's National Security Photonics Center provides photonics technology based solutions (science, technology, microsystems, subsystems, prototyping and low volume production) for National Security customers
Sandia designs, develops, builds and delivers highly sensitive, reliable micro- and nano-scale optical solutions across electromechanical and biological domains for physical sensing and optical signal processing in national security applications.
Sandia uses microfabrication techniques to create novel approaches and methodologies for micro and nano-scale optical sensing and control. These approaches are utilized alongside proven opto-electro-mechanical techniques to push performance limits in displacement and acceleration sensing, optical wavefront control and beam shaping. Sandia applies these capabilities with system-level input to build high-performance, reliable, integrated systems such as inertial and acoustic sensors, high speed optical switches and modulators, adaptive optics systems, micro-spectrometers, integrated optical circuits and on-chip fluorescence-based sensors for microfluidic systems.
Optical MEMS microphone arrays offer extreme fidelity to size ratio. Owing to the precision of micromachining technology, the elements in these arrays have precisely matched dynamic frequency response. This combination makes the technology ideal for integration with advanced signal processing algorithms for directional sensing and source localization using sub cm 2 aperture systems.Nanophotonic Optical Transducers for displacement Sensing
Nano-grating based Low-G inertial sensor
The goal is acceleration sensing in the nanoG scale (~10 -9 m/s 2 ) This would mean a system-based approach to enable continued advancement of inertial sensor research in applications including geolocation, seismology and navigation.
Sub-wavelength grating structures are coupled in the near field. As a result, very small changes in lateral displacement are detectable as changes in optical reflectance. This effect was first predicted and observed at Sandia Labs. Sandia is implementing practical designs to realize a new class of highly sensitive accelerometer devices.
Diffractive optical elements (DOEs) can fulfill classical optical functions such as focusing, but can also provide unique functions, e.g. beam shaping, that conventional optics simply cannot accomplish. Realizing effective DOEs requires numerical analysis and optical design as well as precision photolithographic fabrication capability – all available at Sandia’s Microsystems and Engineering Sciences Application (MESA) facility. Sandia has demonstrated a wide array of diffractive optical devices for diverse applications.
Example devices include:
- Diffractive lenses for wavelengths from the UV to IR (see below)
- Diffractive beam shapers and spot array generators
- Form birefringent waveplates
- Pixelated polarization components, i.e. polarizers and waveplates
- Pixelated spectral filters
- Resonant gratings (see below)
Diffractives – Devices such as lenses and gratings are routinely fabricated at Sandia. The gratings shown below exhibit high aspect ratio features fabricated with excellent uniformity, a critical parameter for device performance. Diffractive lenses often are applicable where conventional lenses are not. The example below shows a diffractive lens specifically designed to focus an incoming laser to an off-axis location with the proper aspheric phase corrections included to avoid unwanted aberrations.
Resonant Gratings – Another excellent example of the micro-optical devices enabled by Sandia’s capabilities are resonant gratings known as guided mode resonance filters (GMRF) or resonant subwavelength gratings (RSG). The combination of a slab waveguide and subwavelength grating creates a device with a resonant reflection; effectively producing a mirror that reflects only a specific wavelength. The gratings are fabricated using e-beam-based lithography with a precision difficult to discern even in the scanning electron micrograph shown below. The four gratings look identical but are in fact subtly different, with each reflecting a different wavelength. This property was used to demonstrate a rotary position encoder (inset) using the different wavelengths as ‘bits’ that were read out optically at 16 positions.
Going beyond the fabrication of individual devices requires the integration of optics into larger assemblies. Sandia has prototyped several micro-optic based assemblies including the examples shown below.
A recent project on advanced gyroscopes based on nuclear magnetic resonance required a miniaturized optical assembly. The final assembly is shown below with a gas cell (hidden by brown mount) and active components attached.
Another example of Sandia’s work with micro-optic based assemblies is the integration of diffractive collection lenses with surface ion traps fabricated at Sandia. For this project, a unique alignment method was developed to allow for exquisite alignment accuracy of the lens to the ion trap without contact being made during alignment.
Sandia provides the creation, development and prototyping of primarily compound semiconductor-based components addressing high-performance, harsh-environment communication, sensing, and control applications.
Sandia provides photonic microsystem solutions and develops, matures, and applies photonic technology to provide highly differentiated national security solutions for internal and external customers. Technical program area activities include surface-normal and guided-wave optoelectronics, optical and microwave microelectromechanical devices and systems, compound semiconductor epitaxy, and rad-hard and high-power density microelectronics.
Examples of device and circuit technologies Sandia has researched, developed and delivered include:
- Specialty semiconductor lasers
- Integrated VCSEL-RCPD circuits (vertical-cavity surface-emitting lasers, resonant-cavity photodiodes); photonic integrated circuits (GaAs, InP)
- Optical amplifiers, modulators, photodetectors, and switches
- Planar lightwave circuits (SiON materials set) such as various optical guided-wave filters and switches; optical data links
- Micromirror arrays and subsystems for switch matrices and adaptive optics
- Radio-frequency switches and networks that include phase shifters and tunable filters; power amplifiers; low-noise amplifiers
- Rad-hard heterojunction bipolar transistors
- High-electron mobility transistors.
To support the needs of next generation optical communications, researchers have developed a Sandia Silicon Photonics platform that leverages the semiconductor and nanotechnology capabilities of Sandia’s Microsystems and Engineering Sciences Applications (MESA) complex to reduce the power dissipation of interconnects within digital systems. Silicon photonics offers a potential breakthrough in optical interconnection performance, not only for supercomputer applications, but also for data communication and other applications.
For more information about fabrication and prototyping of silicon photonics, please see the Fabrication and Testing Capabilities page.
As integrated circuit chips now incorporate over a billion transistors and single boards provide multi-teraflop (1012) computing capacity, the bandwidth and energy required to communicate data within and between integrated circuits are becoming a primary performance bottleneck. Information and communications technology (ICT) is responsible for up to 10% of the US electricity consumption, with data centers responsible for about one fourth that amount, and power consumption is projected to increase dramatically in the coming decades. Silicon photonics offers a potential breakthrough in optical interconnection performance for supercomputer and data communication applications. Importantly, silicon photonics can ride on the progress of silicon electronics and, when mature, will likely achieve the high yield, high reliability, and low costs common in the electronics industry.
Silicon photonics devices are comprised of silicon nanowire waveguides clad in silicon dioxide (SiO2). The large refractive index contrast between the silicon waveguide and the oxide cladding allows light to be routed in the waveguide. Because the micro-disk resonators are so small, resonant electrically–controlled optical modulators can have capacitances as low as 20 femtofarads, and can operate with an electrical power usage of 3.2 femtojoules (fJ) per bit or lower, or 40 μW for 12.5 gigabits per second of information. This power savings is critical in high performance computing and satellite communications, especially for communications from cooled focal plane arrays. Preliminary cryogenic and radiation testing results suggest a promising future for silicon photonics devices to operate in space.
Sandia has demonstrated many leading-edge silicon photonics devices for applications in communications, sensing, and computing. In addition to the optical resonant modulator described above, Sandia has demonstrated silicon photonics optical switching building blocks for optical networks. These may enable lower energy consumption in some applications by avoiding the optical to electrical to optical conversions that are part of optically interconnected, electrically routed networks.
Mach-Zehnder Modulator with Traveling-Wave Electrodes 20GHz, Vpi x L = 0.8Vcm
Full C-band tunable micro-ring filter
Si Nitride Microdisk Resonator
Photodetectors are essential components for an optical network or an optical communication link, converting light into electrical signals. Sandia has demonstrated ultra-compact wave-guide coupled Germanium detectors with world-class performance as part of Sandia Silicon Photonics platform. Sandia’s compact detector occupies less than 20 square microns area and has responsivity of 0.8 A/W and bandwidths up to 45 GHz and NEP of 0.2 pW/Hz1/2. In addition to optical interconnect applications, Sandia is continuing its efforts to develop advanced detectors for RF and quantum applications. For more information about Detectors please see the Quantum Systems and Sensors pages.
Sandia is developing heterogeneous integration technologies that could enable compact integrations of subcomponents based on disparate technologies, such as silicon photonics, complementary metal–oxide–semiconductor (CMOS), and III-V compound semiconductor. Heterogeneous integration allows optimization of each subcomponent independently, thus leveraging the best available technologies to create complex microsystems.
As an example, Sandia has demonstrated integration of advanced CMOS with silicon photonics using flip-chip technology with low-capacitance and low-resistance bond pads and contacts.
Radio frequency (RF) designs from integrated circuits to board level that are direct development of applications based on RF/microwave microelectronics research projects at Sandia National Laboratories. Sandia’s RF and Opto Microsystems group focuses on both microwave component support for defense program radars and the transition of compound-semiconductor research to development and subsequent application.
Custom radio frequency integrated circuits (RFIC) and monolithic microwave integrated circuits (MMIC) reduce size and weight without sacrificing performance. Sandia’s RF & Opto Microsystem department has demonstrated expertise in custom integrated circuit designs for radar and communication applications using advanced modeling and characterization techniques.
Sandia conducts work on passive unique signal wake-up circuits, which are microcircuits that wait using little or no energy until a long, unique signal is received. The energy gathered from this long signal (process gain) is concentrated to “throw” a switch connecting a stand-by battery to a main circuit.
Surface acoustic wave (SAW) correlators for low power, wireless communications.
For more infomration see Programmable SAW Development, SANDIA REPORT, SAND2004-5255, Unlimited Release, Printed October 2004.
Sandia has expertise in real time spectrum analyzers, which are low-power, small, hand carried spectrum analyzers that can monitor many channels in real-time. These devices are quick-reacting, which enables them to monitor non-conventional frequency hopping transmissions.
Passive sensors interrogated by 1 mW “radar guns” give 8-bit accuracy at 10 meters with omnidirectional antennas. These sensors are often used to instrument a complex system after deployment, when it is difficult to tap into power and data buses but there is an apparent need for more monitoring.
Optical Data / Telecommunications
Sandia’s RF & Opto Microsystem department has expertise in the development of ultra high-speed digital integrated circuits and photonic semiconductor devices for the telecommunications industry. Optical and high-speed characterization is performed on discrete devices and integrated circuits in die or wafer form using analytical probe stations. These devices can then be integrated to form an optical transmitter or receiver module that meets the customer requirements. All measurements can be performed in temperature environments that exceed the standard military range.
For more information about research and development in this area, please visit Nanodevices and Microsystems
Fact Sheets, Publications, References, Animations, Licensing IP Opportunities
|Silicon Photonics for Low-Energy Optical Communications||Programmable SAW
|Compound Semiconductor III-V Photonics||Heterogenous Integration/Advanced Packaging|
Visit https://ip.sandia.gov/ for the latest licensing opportunities.
Selected PublicationsControl of Integrated Micro-Resonator Wavelength via Balanced Homodyne Locking
Author(s): J.A. Cox, et.al.
Bit-Error-Rate Monitoring for Active Wavelength Control of Resonant Modulators
Authors: W.A. Zortman, et.al.
Ultra-Low Crosstalk, CMOS Compatible Germanium Waveguide Crossings for Densely Integrated Photonic Interconnection Networks
Authors: A.M. Jones, et.al.
Ultra Compact 45 GHz CMOS Compatible Germanium Waveguide Photodiode with Low Dark Current
Authors: C.T. DeRose, et.al.
Low-Voltage Differentially-Signaled Modulators
Authors: W. Zortman, et.al.
Integrated CMOS Compatible Low Power 10Gbps Silicon Photonic Heater Modulator
Authors: W. Zortman, et.al.
Vertical Junction Silicon Microdisk Modulators and Switches
Authors: M. Watts, et.al.