- Frequency Agile Lasers
Performance of this compact wavelength-tunable single-frequency Nd:YAG CW laser is based on selection of the longitudinal modes of the cavity. Tuning the lasing frequency is achieved by selective “injection” of the cavity losses in all but selected modes. The laser concept allows random lasing wavelength tunability with switch time less than 0.5 ms. The figure below illustrates a typical example of wavelength tunability.
Fabry-Perot spectrum of a randomly tuned lasing wavelength of the CW Nd:YAG laser
- Self-Organized Broadband Fiber Array Laser
The self-organized fiber-array laser enables coherent coupling of a broadband fiber channels inside a laser cavity of stable configuration. This configuration of the fiber array enables effective coupling of multiple high-power fiber channels. We have recently demonstrated performance of this laser in TEM11 and TEM02 lasing modes converting them to a single beam with the flat wavefront. The proposed architecture can be affective for combining high-power fiber channels, providing output in excess of 100 kW.
Far-field of the four-channel array and coupled-beams oscillation
- Intra-Cavity Coherent Optical Amplifier (ICOA)
Coherent imaging optical amplifiers are essential elements of various EO systems. AS&T’s unique ICOA architecture enables high performance with no need to adjust the cavity modes and the spectrum of the object-returned signal. ICOA will expand the capabilities of coherent imaging systems.
- Seeded Q-Switched Laser
Tunable single-frequency short-pulse lasers are critical for various application, including coherent LADAR, used for acquisition, tracking, identification and characterization of distant objects. holographic imaging system, dynamic spectroscopy, and other. The AS&T Q-switched laser performs in a seeding regime with no need in adjustment of the seeded radiation spectrum to cavity modes. This feature allows oscillation of short laser pulses with the spectral pattern of interest and synchronized to external processes. The unique features of this laser allow to reproduce the spectrum of the seed radiation as a single frequency, as well as of an arbitrary structure within the bandwidth of the gain medium.
- Conformal Imaging Vibrometer (CIV)
Conformal Imaging Vibrometry (CIV) provides the ability to fully characterize the spatio-temporal dynamics of an object of any arbitrary geometry by deploying a laser beam array tailored to the specific structural geometry of interest (planar, circular, cylindrical, spherical or an arbitrary curved/warped 2D or 3D surface). This approach enables high-speed vibration imaging of whole-body structural dynamics in real-time, with no multiplexed data capture or synthesized reconstruction of the motion, as is currently employed in existing commercial vibrometers.
- Structural Damage Assessment
CIV can be employed as a diagnostic tool for nondestructive examination (NDE) and quantitative assessment of damages in a wide range of materials and structures (composite materials, metals etc.). The CIV photonic sensor is designed to support fast, full-field, optical non-contact inspection of planar or curved surfaces providing both global structural integrity analysis and local defect detection.
- MEMS Characterization
CIV is configured to support dynamic imaging of the real-time structural behavior of macro and micro vibratory resonators, including planar and 3D micro electromechanical systems (MEMS) and to provide insight into transient structural interactions, including coupled vibrations and modal non-degeneracy (mode splitting) – important features for the development of current and next generation vibratory gyroscopes and MEMS resonators. The conformal optical fiber probe architecture is uniquely suited to the vacuum environment required for device testing, making the sensor perfectly suited for streamline characterization and optimization of batch-fabricated 3D micro-resonators.
- Fiber Optic Sensors
Design, construction, and calibration of robust temperature/pressure fiber optic sensors and/probes. Development and implementation of individual sensor interrogation systems and/or of read-out circuit for simultaneous interrogation of both temperature and pressure probes.
- Wavefront Sensors (WFS)
- Beaconless WFS
The adaptive optics (AO) is a key element of various optical systems where the correction of the wavefront is essential. This includes laser beam propagation in turbulent environment, analysis and correction of wavefront aberrations, free space communications, others. Effective performance of the AO system requires a tight beacon at the terminal point of the propagation path. In majority of practical scenarios when dealing with an extended (image resolved) target, solution to the problem of forming a localized beacon though perturbed medium is non-trivial and therefore remains unresolved. Existing AO systems do not perform without well-localized laser beacon. The AS&T unique beaconless approach enables accurate wave-front sensing (WFS) when operating against an extended area target illumination with coherent or incoherent light source.
- Laser Beam Control
Control of the structure of the laser beam is essential for various practical application scenarios, such as correction of the wavefront distortions and aberrations of high-power laser pulses due to spatial refraction index modulations of the gain medium. Similar problems exist for laser beam propagation through inhomogeneous medium. AS&T is involved in development of the concept of the laser beam control system with its operation based on the non-linear four-wave mixing effect that when fully developed should enable effective correction of the characteristics of the laser beam operating in a short-pulse or quasi-CW regimes.
The dynamic of laser beam focusing on a distant rough-surface object after n-th sequential round trips. Cn2 = 5?10-14 m-2/3, distance to the object is L = 5 km, the transmitter/receiver aperture is D = 60 cm.
Data Handling & Fusion
- Conformal OE System
- Parallel Opto-Optical Encoded Data
Ultra-high speed (up to 4 Gb/sec) technique for a parallel exchange of spatially encoded optical data with no autocorrelation and flexible error correction.
- OE Multi-Channel Data Analyzer
High-speed opto-electronic digital processor with high-density (hundreds of channels) parallel fiber optic input and digital output to parallel FPGA processor array. Architecture integrates high-density mezzanine Indium Gallium Arsenide (InGaAs) receiver array with high-density digitizers for massive parallel processing of heterodyned C-band infrared optical signals. Applications include imaging lidar, conformal imaging vibrometry, general purpose remote sensing and multi-channel free-space optical communications.
- Hetrogeneous Data Fusion
- Direct Fusion using Hidden Markov Models
Fusion of highly disparate data sources differing in sampling rate and format for enhanced objects identification, discrimination and characterization. This technology is essential to increased effectiveness in the performance of intelligence, surveillance and reconnaissance (ISR) as needed by several branches of DoD, Homeland security, and commercial sectors, including medical applications, teleconferencing, smart-grids, others.
- Compressive Sensing
Dimensionality reduction of multiple massive sensor streams to a tenable level.
- Low Latency Tracking
High speed motion capture which avoids the costs and bottlenecks of camera based units while tracking arbitrary numbers of fiducials
- GPS/IMU Trajectory Refinement
Simulation and modeling of enhanced tracking in high-performance regimes where rapid shifts in occlusion often occur.
- Multi-Sensor Tracking
Integration of multiple bands and locations in a common operating environment via feature detection and heterogeneous data fusion to enable for greater reliability and resilience.