Amarildo J. C. Vieira

Application of RADAR technology to aerial LIDAR systems for enhancement of shallow underwater target detection

Since microwaves do not penetrate water, RADAR, the principal tool for remote sensing of the earth and atmosphere, cannot be used directly for the detection of underwater objects. Currently, aerial light detecting and ranging (LIDAR) systems are therefore preferred for the detection and ranging of objects submerged in the sea. LIDAR provides for large area coverage at high speed, but it lacks coherent detection capability, a shortcoming that severely limits system sensitivity and underwater target contrast. In response to this problem, this paper details the merging of RADAR and LIDAR technologies in the constitution of a hybrid LIDAR-RADAR detection scheme. This new sensor configuration has reduced incoherent backscatter clutter by 17 dB in laboratory experiments and related computer simulations. >

Rapidly tunable millimeter-wave optical transmitter for lidar-radar

This paper reports on the optical generation of a rapidly tunable millimeter-wave subcarrier for lidar-radar. The millimeter-wave signal is generated by beating the output from two Nd:YVO/sub 4//MgO:LiNbO/sub 3/ electrooptical monomode microchip laser sections realized monolithically in a single composite crystal. The device has a continuous tuning range up to 45 GHz. The measured chirp rate is 3816 THz/s, the voltage sensitivity is 10.6 MHz/V, and the measured residual phase noise is -106 dBc/Hz at 10-kHz offset.

Nd:LiNbO/sub 3/ microchip laser with 20 GHz subcarrier

This paper reports on the development of a 20 GHz mode-locked Nd:LiNbO/sub 3/ microchip laser operating at 1.084 /spl mu/m with an output power greater than 35 mW (CW). With this configuration, a single device simultaneously generates the optical carrier and the microwave subcarrier. A modulation index of 96% was obtained for a driving microwave power of 12.6 dBm at 20 GHz. An information signal up to 8 GHz was also superimposed on the 20 GHz subcarrier using an external modulator.

Experimental and Theoretical Analysis of a Microwave-Modulated LIDAR System

This paper concerns the merging of the lightwave and miscrowave technologies for improvements in sensitivity and resolution of aerial light detecting and ranging (LIDAR) measurements. By the transposing of a microwave signal on a blue-green optical carrier, a hybrid LIDAR-RADAR detection scheme was created. Simulations and laboratory measurements showed a dramatic 17 dB optical (34 dB electrical) suppression of the backscatter clutter and corresponding improvement in contrast for shallow underwater targets.

Microwave-modulated transmitter design for hybrid LIDAR-RADAR

The application of well-established, coherent RADAR technology to aerial light detecting and ranging (LIDAR) systems has reduced incoherent backscatter clutter by 17 dB in laboratory experiments and computer simulations. The full-scale experimental realization of this hybrid LIDAR-RADAR system is hampered by the unavailability of a stable modulation source capable of providing high peak powers to overcome the large dynamic range required for the LIDAR backscatter measurement. Two methods being investigated for the microwave-modulation of a transmitted optical pulse to be utilized in the actual LIDAR environment are detailed.<<ETX>>

Microchip laser for microwave and millimeter-wave generation

A Nd:LiNbO/sub 3/ microchip laser operating at 1.084 /spl mu/m wavelength was designed, implemented, and characterized. The laser cavity was designed to have a free spectral range (FSR) of 20 GHz and an output optical power greater than 20 mW. By exploiting the electrooptical properties of the lithium niobate host, it was possible to mode-lock the microchip laser at 20 and 40 GHz. With this technique it was possible to optically generate the subcarrier with a high modulation index (95.6%).

Bulk Fabry-Perot intensity modulator for LIDAR systems

This letter reports on a built Fabry-Perot modulator operating at high optical intensities in the blue-green optical region. The design, fabrication, and characterization of a prototype modulator using LiNbO/sub 3/ as the host material with mirrors deposited directly on the end facets of the crystal are described. A measured modulation depth of 23.9% was achieved.

Chirped lidar-radar for medical diagnostics

This paper concerns a chirped lidar-radar system for medical diagnostics. The microwave/millimeter wave modulated optical signal is generated by beating the output of two Nd:YVO/sub 4//MgO:LiNbO/sub 3/ single mode microchip lasers. The device can be tuned from DC to 100 GHz, with a sensitivity of 8.8 MHz/Volt at a chirping rate of over 1000 THz/sec.

A New Approach for the Optical Feed of Radio Nodes Utilizing a Microchip Solid State Laser

This paper is concerned with a fiberoptic access to wireless cellular communication systems. The attributes of the central station using a mode-locked solid state microchip laser embeded in a microwave cavity will be discussed. The low cost remote base station design and the network topology for the pico-cellular systems is considered. The approach utilizes commercially available handsets, furnished with a suitable adapter to extend their usage into the millimeter wave range.

Linearity study of a fabry-perot intensity modulator

Abstract A study concerning the linearity and dynamic range of a Fabry-Perot intensity modulator is presented. The 1 dB compression point, second-order harmonic, third-order intermodulation, and dynamic range for a 3 GHz device are determined theoretically and compared with experimental results.