Ariela Donval

Passive components for high power networks

As power in optical networks increases, there is a greater chance of damaging optical components and equipment due to over-power. Here we present the optical fuse, which is a passive component designed to protect against over-power events.

Dynamic Sunlight Filter (DSF): a passive way to increase the dynamic range in visible and SWIR cameras

Regulating optical power levels within various systems, such as cameras, requires today an electronic feedback control or offline data processing, which introduces complex and expensive systems. Sometimes the blooming is such that data is lost and cannot be recovered by any sophisticated software. We explore the unique capabilities and advantages of nanotechnology in developing next generation non-linear components and devices to control and regulate optical power in a passive way. We report on the Dynamic Sunlight Filter (DSF) enabling High Dynamic Range (HDR) for various types of camera. The DSF solution is completely passive and can be added to any camera as an external add-on.

IR and visible wideband protection filter

Imaging and detection systems are susceptible to detector saturation or permanent damage caused by powerful light sources or high power lasers. We propose and demonstrate a passive, solid-state threshold-triggered optical protection filter. At input power below threshold, the filter has high transmission over the whole spectral band. However, when the input power exceeds the threshold power, transmission is decreased dramatically. As opposed to fixed spectral filters, which permanently block only specific wavelengths, the wideband filter is clear at all wavelengths until it is hit by damaging light. When high incident optical power impinges on the wideband filter at a certain spot, this spot becomes permanently opaque. The wideband protection filter is fast enough to block nanosecond laser pulses.

Protecting SWIR cameras from laser threats

SWIR cameras offer the advantage of higher resolution and smaller optical systems than conventional mid and far infrared optical systems. With the ability of seeing at low illumination conditions at the near infrared region, it can provide the detection of covert lasers. The ability of laser detection introduces the risk of sensor damage when the laser power is above a certain threat level. Smart protection is therefore needed, that is transparent for low laser intensities and limit or block the high laser intensities, and is effective over a wide band of wavelengths. We developed an Optical Power Control (OPC) device that reduces laser power threat to a safe level for a variety of optical systems. The talk presents a novel technology for protection of SWIR cameras against laser threats.

Optical Power Control Filters: from Laser Dazzling to Damage Protection

With the development of more powerful lasers for applications, optical limiters and blockers are required for providing human eye and optical sensors protection. In some scenarios, laser radiation may seriously interrupt the signal, from transient saturation and can lead to permanent damage. We present a variety of non-linear, solid-state dynamic filter solutions protecting from dazzling and damage in a passive way. Our filters either limit or block the transmission, only if the power exceeds a certain threshold as opposed to spectral filters that block a certain wavelength permanently. We propose a dynamic protection for cameras, sensors and the human eye from laser threats.

Anti-dazzling protection for Air Force pilots

Under certain conditions, laser directed at aircraft can be a hazard. The most likely scenario is when a bright visible laser causes distraction or temporary flash blindness to a pilot, during a critical phase of flight such as landing or takeoff. It is also possible, that a visible or invisible beam could cause permanent harm to a pilots eyes. We present a non-linear, solid-state dynamic filter solutions protecting from dazzling and damage in a passive way. Our filters limit the transmission, only if the power exceeds a certain threshold as opposed to spectral filters that block a certain wavelength permanently.

Increasing dynamic range of cameras with dynamic sunlight filter (DSF)

Todays battlefield is using imaging systems everywhere, starting from simple observation systems and up to very sophisticate warning and offensive systems. Cameras are integrated in almost all systems. Regulation and control of optical power in cameras presently requires an electronic feedback control or offline data processing, which introduces complex and expensive systems. We present a non-linear, solid-state passive dynamic sunlight filter (DSF) performing this process, yielding similar results - passively. When sunlight intensity increases, the DSF transmission decreases according to the amount of the incident lights, resulting in a darkened state, which is limited only to the over exposed area. The area returns to transparency once the amount of light decreases below a threshold level. We demonstrate here new experimental results showing an increase in the cameras dynamic range when using the DSF.

Smart filters: protect from laser threats

Optical systems as well as the human eye are susceptible to saturation or damage caused by high power lasers. We present a non-linear, solid-state passive wideband optical protection filter. As opposed to fixed spectral filters, which permanently block only specific wavelengths, the wideband filter is clear at all wavelengths until it is hit by damaging light. At input powers below threshold, the filter has high transmission over the whole spectral band. However, when the input power exceeds the threshold power, transmission is decreased dramatically. We propose a novel technology for protection of any imaging system, sensors and the human eye against laser threats from the visible and up to the IR.

Low loss optical interconnects to silicon waveguides

Waveguides fabricated in high-index-contrast material systems offer very strong light confinement compared to that achieved in low-index-contrast material systems. A core layer of silicon (refractive index n~3.5) surrounded by silica cladding (n~1.5) on a silicon-on-insulator (SOI) substrate is an example of a high-index-contrast material system. This enables miniaturization of functional optical components and enhances dense integration of devices on waveguide chips. Some physical effects, such as, Raman and Stimulated Brillouin Scattering (SBS) are much stronger in silicon than in glass. In view of the above two reasons, it is possible to use short (a few centimeter long) silicon waveguides to amplify light or modify its wavelength, instead of using kilometers of glass optical fibers. A large mismatch between the common optical fiber dimensions and that of the high-index-contrast waveguides makes it difficult to couple light in and out of the chip. A number of techniques have been utilized for this purpose, including prism couplers, grating couplers, tapered fibers and micro-lens mode transformers [ 1, 2]. A better option to effectively couple light in this situation is by incorporating a waveguide section that is tapered vertically, as well as laterally between the fiber and the waveguide. This tapered section acts as a classic adiabatic modal transformer [ 3, 4, 5, 6] that transforms the input fundamental mode shape to that of the waveguide mode. In this paper, coupling losses between optical fibers and rib-loaded SOI waveguides with lateral only (1-D) and combination of lateral and vertical (2-D) tapers are presented. The waveguide fabrication process down to 0.75 μm size with the tapers is discussed and the measured coupling losses are compared to predictions. Measured coupling loss values for waveguides with 2-D tapers (~1.8 dB) show a significant improvement over those for waveguides with 1-D tapers (~4 dB) or no tapers (~8 dB), and are in excellent agreement with predictions. A qualitative analysis of the Free Carrier Absorption (FCA) phenomenon in narrow silicon waveguides that suppresses the Raman amplification and SBS is also shown.

Lasers pumped quantum dynamics in nanostructured arrays for computing

Quantum computation uses qubit in superposition and entanglement states providing more sophisticated computation ability regarding today’s computers. For that purpose of developing a novel computer concept exploiting quantum dynamics at the nanoscale, we joined an EC H2020 program consortium named COPAC [1]. We propose to analyze the nonlinear 2 dimensional optical response of assembled nanostructures in solid arrays to a sequence of short laser pulses. Based on 2D maps of the stimulated emission we implement a novel paradigm for parallel information processing. Within the COPAC project, we, in KiloLambda, will develop the device nanostructure and engineering design.