Lockheed Martin Corporation

General Electric Company

Martin Marietta Corporation

Thomas William Karras

Stephen V Robertson

Arthur C Paolella

Harvey L Wagner

William H Meise

Anthony C Kowalczyk

William Joseph Taft

Paul Kit Lai Yu

George Silverman

Jeffrey T Sroga

David L Enlow

Michael S Margulis

Carl E Anderson

Stephen Voiers Robertson

An integrated multi-channel photonic radio-frequency (RF) receiver system includes a master oscillator including a laser source configured to generate laser light. A local oscillator (LO) path may include an LO generator, an LO modulator, an optical LO filter, and an optical amplifier optically coupled to one another to generate an LO signal. Multiple RF-modulation channels are coupled through an optical switch to a number of channel filters and configured to produce a number of filtered RF-modulated optical signals. An optical combiner may combine the LO signal with each filtered RF-modulated optical signal to generate down-converted optical signals. Each channel of the plurality of RF-modulation channels includes a channel laser coupled to a channel modulator, and the LO generator and channel lasers of the RF-modulation channels are fed by the laser light of the master oscillator.

Integrated multichannel photonic receiver

A compact photonic radio frequency receiver system includes a laser source that is configured to generate laser light Radio frequency (RF) and local oscillator (LO) input ports may receive RF and LO signals, respectively. One or more miniature lithium niobate waveguide phase modulators may be coupled to the laser source to receive the RF and LO signals and to modulate the laser light with the RF and LO signals in a first and a second path, and to generate phase-modulated laser lights including an RF-modulated light signal and an LO-modulated light signal. A first and a second miniature filter may be coupled to the miniature lithium niobate waveguide to separate a desired spectral band in the phase-modulated laser light of the first path and to facilitate wavelength locking of the laser light of the second path. An optical combiner may combine output laser lights of the first and second filters.

High performance compact RF receiver for space flight applications

A compact photonic radio frequency front end receiver system including a laser chip source, radio frequency and LO inputs, an optical modulator chip coupled to the laser source and the radio frequency and LO inputs, a millimeter scale optical radio frequency multi-pole filter coupled to the optical modulator, an optical switch array chip coupled to the optical radio frequency multi-pole filter, and a detector chip coupled to the optical switch array, all with micro-optic coupling, heterodyne signal recovery, and wavelength locking.

Photonic radio frequency front end receiver

A compact photonic time delay unit. The unit includes a plurality of compact optical delay elements, a plurality of delay bypass elements, with each delay bypass element being associated with a respective one of the compact optical delay elements, and a plurality of compact optical switches. Each of the compact optical switches is configured to controllably switch an optical signal through one of the compact optical delay elements or through the associated delay bypass element. In some aspects, the compact optical delay elements, delay bypass elements, and compact optical switches are disposed on a single electro-optical chip.

Compact time delay unit

A signal processing system includes an input for receiving an input signal, a light source for generating an optical carrier signal having a pre-determined wavelength, a modulator for receiving the input signal and the optical carrier signal and modulating the optical carrier signal based upon the input signal, and an optical filter having a plurality of signal channels, wherein at least one of the signal channels is locked by a reinsertion of the optical carrier signal to pass signals having a wavelength substantially the same as the wavelength of the optical carrier signal.

Wavelength locked channel select

An optical filter is disclosed, including a first optical filter adapted to receive a first optical signal including an optical carrier frequency and a plurality of interference signal components. The first filter produces an output signal at the optical carrier frequency and a reflection signal. The output signal is split into a peak detection path signal and a re-insertion path signal. An optical power detector converts the peak detection path signal into an electrical control signal and aligns the optical carrier frequency to a resonance frequency of the first filter to maximize the power of the optical carrier frequency. A second optical filter receives the reflection signal and selects at least one spectral component while rejecting other spectral components and outputs a filtered signal that carries the selected spectral component. A signal combiner receives and combines the filtered signal and the re-insertion path signal.

Optical RF filter wavelength locked to laser with fixed offset frequency

Systems and methods of forming an optical coupling between two optical waveguides where at least one of the optical waveguides is non-UV transmissive are disclosed. In one aspect, a self-forming waveguide (SFWG) is formed in a photosensitive material disposed between a UV transmissive optical waveguide and a non-UV transmissive component at least in part by a portion of an incident UV beam reflected from an interface between the photosensitive material and the non-UV transmissive material. In another aspect, two separate SFWG waveguides are formed in two separate photosensitive materials by UV beams passed thereto via a UV transmissive bridge waveguide.

Self forming waveguides for optical coupling and methodologies for making same

A receiver system comprises an antenna configured to receive an input RF signal, a high spur free dynamic range modulator configured to receive the input RF signal from the antenna and to convert the input RF signal to an optical signal, and a tunable filter configured to receive the optical signal and to output a filtered optical signal. The tunable filter includes at least one electro-optic resonator, at least one electrode configured to supply an electrical control signal to the electro-optic resonator, and a controller configured to adjust the electrical control signal to adjust a refractive index of the electro-optic resonator, whereby a resonant frequency of the electro-optic resonator is selectably adjusted. The receiver system further comprises a receiver configured to receive the filtered optical signal.

High spur-free dynamic range receiver

Exemplary methods of maximizing a spur-free dynamic range (SFDR) or a gain of an electro-absorption modulator (EAM) are disclosed. At least one parameter in a set of design parameters for an EAM is varied. An SFDR of the EAM is determined in part by a first set of design parameters. A gain of the EAM is determined in part by a second set of design parameters. An output versus bias voltage transfer curve of the EAM is generated. An optimal SFDR bias voltage at which a maximum SFDR occurs for a given optical input power or an optimal gain bias voltage at which a maximum gain occurs for a given optical input power is programmatically determined based at least in part on the transfer curve.

Methods of optimizing spur-free dynamic range or gain in electro-absorption modulators

Systems are disclosed that utilize electrical signals from detectors of an imaging focal plane array or antenna elements of an antenna array to modulate optical signals. Antenna or focal plane array elements are coupled to optical waveguides by way of whispering gallery mode resonators made of electro-optic material. The resonators modulate optical signals in the waveguides based on the electrical signals from the detectors/antenna elements. The signals received by the array are converted into the optical domain, allowing subsequent optical processing and/or distribution. Each detector/antenna element involved can be identified by the specific wavelength and waveguide through which its signal is coupled, enabling subsequent optical processing of the signals such as by wavelength division multiplexing systems. Additionally disclosed are imaging sensor photonic systems that include WDM components and other optical components such one or more optical narrow-band amplifiers and/or filters. Related electro-optic modulation and tuning methods are also described.

Optical focal plane data coupler

An optoelectronic RF signal receiver utilizes a first RF to photonic modulator for receiving an optical carrier signal and an electrical signal from a local oscillator and producing an optical carrier signal with first optical sidebands offset from the carrier signal by the local oscillator frequency. A second RF to photonic modulator receives an electrical RF signal and the signals from the first modulator and produces second sidebands to each of the first optical sidebands from the first modulator with each of the second sidebands being offset from the first sidebands by the RF signal frequency. A detector then receives signals produced by the second modulator and produces an electrical IF signal for further processing. The receiver does not utilize a frequency translation device in the RF signal path and thereby eliminates RF loss, noise, and limited dynamic range characteristic of prior art electro-optical receivers. The two modulators can be biased for optimum linearity and for optimum rejection of in-band spurious signal products.

Superheterodyne photonic receiver using non-serial frequency translation

An optical fiber that transforms light of undesired polarization into light of desired polarization. In principle, the signal power of the non-preferred polarization is transformed into signal power of the preferred polarization, thereby actually transforming the polarization. The fiber can have a circular end for input of light having randomly phased polarization, and an elongated end for output of light having a single principal orientation component. A generally smooth transition from the circular end to the elongated end causes substantially all the light entering the fiber to exit from the fiber without losing light due to reflection or radiation. Alternatively, the fiber can have a lobed end, for input of light having first and second mutually orthogonal polarization components, and an elongated end, for output of light having a single principal orientation component. Alternatively, the fiber can be a combination of the two forms described above. That is, the fiber can have a circular section that transforms first into a lobed section with increasing distance from the input port, with the lobed section then transforms into an elongated (e.g., elliptical or ovoid) section with increasing distance from the input port.

Light polarization transformer

A microphotonic circuit includes one or more light control elements such as modulators or switches coupled in polymer waveguides, and controlled by electrical bias fields produced by voltage or light sources. Each modulator or switch includes at least one polymer waveguide having a high-.eta. core and surrounding low-.eta. cladding, to constrain the light. An electrooptic control element is evanescently coupled to the core of the first waveguide by spacing from the core. The coupling between the core and the control element depends upon the relative .eta.s of the core, cladding and electrooptic element. Bias is applied to maintain the electrooptic element in one of at least two possible states, one of which prevents coupling between the electrooptic element and the core, and the other of which permits such coupling. The bias may be applied in the form of electrical voltage or light. In some embodiments of the invention, a second optical waveguide is coupled to the electrooptic element. The coupling of the second waveguide may be evanescent or direct.

Planar microphotonic circuits

An optical demultiplexer includes an electrooptic modulator (410) which modulates a beam of light (418) in response to frequency-multiplexed radio-frequency (RF) information signals, to produce diverging beamlets of light (420). The diverging beamlets are separated by a spatial separator arrangement (426), and each beamlet (420), including the information of its RF carrier, is coupled to a separate optical detector (428). The detector (428) can extract amplitude modulation from the signal. In order to reconstruct the RF signal as well as the amplitude modulator, an optical 'local oscillator' signal (OLO) is coupled to each detector together with its information signal. Signal loss due to vibration or misalignment is avoided, and heterodyne mixing efficiency is maximized in an embodiment of the invention, by propagating the OLO and information signals through a single-mode optical fiber to the detector. In a particular embodiment of the invention, the OLO signal is applied to a first fiber (622), the information signal is applied to a second fiber (610), and the first and second fibers are coupled together by a fiber-optic coupler (612). In another embodiment of the invention, the OLO signal results from generating an RF L.O. signal, and combining the RF L.O. local signal with the information signals before application to the electrooptic modulator, to generate an OLO beamlet (720) which is subject to the same vibration and misalignment as the signal beamlets.

Growing community of inventors

Berwyn, PA, United States of America

Thomas William Karras