United States of America As Represented by the Administrator of Nasa

Jeffrey R Chen

Guangning Yang

Kenji Numata

Stewart T Wu

Mark A Stephen

Hui Li

The present invention relates to a lidar system including: laser transmitter and receiver systems, the laser transmitter system including: a wavelength-tunable seed laser which emits pulses at selected wavelength points, and switches between wavelengths within a switching time of <200 ns; a fiber amplifier which amplifies the laser pulses up to 200 kW to a transmitter grating; and a transmitter telescope including primary and secondary mirrors. The laser beam is directed from the transmitter grating to the secondary then primary mirrors, and the first transmitter grating is imaged on the primary mirror to minimize laser beam wander thereon. The transmitter grating diffracts and steers the laser beam by wavelength to a surface, to an arbitrary subset of <2000 resolvable footprints along a cross-track direction at a beam pointing angle switching time of <200 ns, such that footprints illuminated by the laser beam on the surface are imaged in 3D.

3-dimensional imaging lidar system

A satellite includes a fast tracking mirror ('mirror') placed at or near center of mass (CoM) of the satellite along a line of sight between the CoMs of two satellites. The satellite also includes a detector at a distance away from the mirror. The mirror is adjusted to maintain the distance between the mirror and the detector, when a location of the detector changes due to pitch and yaw of the satellite.

Active pointing and tracking system

A photonic, integrated circuit chip can have a frequency comb laser configured to generate a plurality of wavelengths, a plurality of modulators, one respective modulator for each wavelength of the plurality of wavelengths, the plurality of modulators being aligned in series with each of the plurality of modulators being tuned to a respective one of the wavelengths of the plurality of wavelengths, a connector configured to convey a drive signal for each modulator of the plurality of modulators, a semiconductor optical amplifier configured to receive light exiting from the plurality of modulators, and a chip having present thereon the frequency comb laser, the plurality of modulators, and the semiconductor optical amplifier. The plurality of modulators can be configured to produce a single beam of time-interleaved, multiple-wavelength output laser light. A mobile system, such as a satellite, can also have the photonic, integrated circuit chip as a component thereof.

Integrated multi-wavelength WDM TDM lidar transmitter

An apparatus for improving a pointing capability of an optical pointing system includes a star tracker attitude control system for maintaining an alignment between the optical pointing system and a target, a beam steering mirror controlled by the star tracker attitude control system to direct an optical signal to impinge on the target, a fixed optical assembly configured to direct a portion of the optical signal from the bean steering mirror into a field of view of a star tracker telescope of the star tracker attitude control system, and a detector array for detecting the portion of the optical signal superimposed over a location in a current star scene in the star tracker telescope field of view, where the star tracker attitude control system is configured to operate the beam steering mirror to maintain the optical signal on the target by maintaining the superimposed signal on the location in the star scene.

Steering mirror assist for laser pointing

An apparatus for measuring a distance between a first and second terminal includes a frame counter for determining a number of data frames traversing a distance between the first terminal 105 and the second terminal, a frame bit counter for determining a number of data clock bits offset between a transmitted data frame and a concurrently received data frame, a data clock phase detector for determining a phase difference between an RF data clock for the transmitted data frame and an RF data clock for the concurrently received data frame, and an optical carrier phase detector for determining a phase difference between an optical carrier used to transmit the transmitted data frame and an optical carrier for the concurrently received data frame. The distance between the first and second terminal is determined from a round trip transit time T between the first and second terminals.

Continuous carrier optical phase optometric measurement over coherent optical communication link

Disclosed herein are systems and methods related to use of hollow core photonic crystal fibers. A system includes a tube and a collimating lens configured in a first end of the tube, wherein a single mode fiber is coupled to a first end of the collimating lens. A second lens is supported by a structure at a second end of the tube, the second lens receiving a first signal from a second end of the collimating lens and outputting a second signal that is coupled into a first end of a hollow core photonic crystal fiber. A first gas tube is configured to introduce gas through the structure into a chamber and a sealant seals at least one of the collimating lens and the structure within the tube. An output signal is received at a detector that catches the entire beam to suppress multiple-mode beating noise.

System and method for using hollow core photonic crystal fibers

An apparatus and method is provided to enable precision and fast laser frequency tuning. For instance, a fast tunable slave laser may be dynamically offset-locked to a reference laser line using an optical phase-locked loop. The slave laser is heterodyned against a reference laser line to generate a beatnote that is subsequently frequency divided. The phase difference between the divided beatnote and a reference signal may be detected to generate an error signal proportional to the phase difference. The error signal is converted into appropriate feedback signals to phase lock the divided beatnote to the reference signal. The slave laser frequency target may be rapidly changed based on a combination of a dynamically changing frequency of the reference signal, the frequency dividing factor, and an effective polarity of the error signal. Feed-forward signals may be generated to accelerate the slave laser frequency switching through laser tuning ports.

Apparatus and method to enable precision and fast laser frequency tuning

A pulsed laser system includes a modulator module configured to provide pulsed electrical signals and a plurality of solid-state seed sources coupled to the modulator module and configured to operate, responsive to the pulsed electrical signals, in a pulse mode. Each of the plurality of solid-state seed sources is tuned to a different frequency channel separated from any adjacent frequency channel by a frequency offset. The pulsed laser system also includes a combiner that combines outputs from each of the solid state seed sources into a single optical path and an optical doubler and demultiplexer coupled to the single optical path and providing each doubled seed frequency on a separate output path.

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Clarksville, MD, United States of America

Jeffrey R Chen