California Institute of Technology

Firooz Aflatouni

Seyed Ali Hajimiri

Behrooz Abiri

Steven Bowers

Andy Zhou

An optical phased array includes, in part, N optical signal emitting elements, and N lenses each associated with a different one of the N optical signal emitting elements and positioned to form an image of its associated signal emitting element, where N is an integer greater than 1. The optical signal emitting elements may be a grating coupler, an edge coupler, and the like. At least a number of the lenses may be formed from Silicon. The optical phased array may optionally include one or more concave or convex lens positioned between the signal emitting elements and the N lenses. The optical signal emitting elements may be formed in a silicon dioxide layer formed above a semiconductor substrate and the lenses may be formed from Silicon disposed above the silicon dioxide layer. The optical signal emitting elements may receive an optical signal generated by the same source.

Integrated optical phased arrays with optically enhanced elements

A camera includes, in part, an optical signal source generating a frequency varying optical signal, a multitude of pixels arranged along rows and columns, an optical focusing element, and an opto-electronic circuit. A portion of the optical signal generated by the optical signal is caused to reflect from a target object and then directed toward the pixels. A multitude of samples of a second portion of the optical signal are combined with the signals received by the pixels to generate a multitude of combined optical signals. The optical signals so combined are converted to electrical signals. Each electrical signal has a frequency defined by a difference between a frequency of the second portion of the optical signal and a frequency of a signal received from a pixel. The frequency differences are used to form an image of the target object.

Coherent camera

An optical phase shifter includes, in part, a waveguide, a heating element adapted to heat the waveguide, and a cooling element adapted to cool the waveguide. The heating element may be integrated within a substrate in which the waveguide is formed. The cooling element is biased to maintain the temperature of the waveguide within a predefined range characterized by a substantially high gradient of the thermal constant of the waveguide. The optical phase shifter may optionally include a substrate on which the waveguide is positioned. The substrate may include, in part, through substrate vias for supplying electrical signals to the cooling element. A control circuit supplies electrical signals to the heating and cooling elements. The control circuit may maintain the cooling element and heating element on concurrently. Alternatively, the control circuit may turn off the cooling element before turning on the heating element.

Thermally enhanced fast optical phase shifter

An optical phased array includes, in part, a multitude of optical signal emitters and a multitude of optical signal phase/delay elements each associated with and disposed between a different pair of the optical signal emitters. Each optical signal phase/delay element is adapted to cause a phase/delay shift between the optical signals emitted from its associated pair of optical signal emitters. Each optical signal phase/delay element is optically a ring resonator that includes a p-i-n junction. By varying the bias applied to the p-i-n junction, the phase/delay generated by the ring resonator is varied. Furthermore, each optical signal emitter is optionally an optical grating having a multitude of grooves. The groove lengths of the optical gratings are optionally selected so as to increase along the direction of travel of the input optical signal through the optical phase array.

Integrated planar optical phased array

An opto-electrical oscillator includes, in part, first and second optical phase modulators, a coupler, an optical-to-electrical signal conversion circuit, and a control circuit. The first optical phase modulator modulates the phase of a first optical signal in response to a first feedback signal to generate a first phase modulated signal. The second optical phase modulator modulates the phase of a second optical signal in response to a second feedback signal to generate a second phase modulated signal. The first and second optical signals travel through first and second optical paths respectively and are generated from the same optical source. The optical-to-electrical signal conversion circuit receives an optical signal from the coupler and in response generates an electrical signal applied to the control circuit. The output signals of the control circuit cause the first and second feedback signals to be out of phase.

Optically balanced opto-electrical oscillator

An electro-optical circuit, includes in part, a modulator, a signal splitter, N signal paths each having one or more signal processing components, N photo-diodes and a signal combiner. The modulator modulates an optical signal using an electrical input signal. The splitter splits the modulated optical signal into N optical signals each delivered to a different one of the N paths for processing by the associated signal processing component(s). Each photo-diode converts an optical signal it receives from its associated optical signal processing component(s) to a current signal. The signal combiner combines the N current signals it receives from the N photo-diodes to generate an output current signal. The signal processing component(s) may be a variable optical delay component, a variable optical gain/attenuation component, or both thus enabling the output current signal to represent a filtered version of the electrical input signal.

Optically assisted electrical filtering and processing

A self-equalizing photo-detector (SEPD) includes, in part, a multitude of optical splitters and photo detectors, and at least one optical delay element. The first optical splitter splits an optical signal into second and third optical signals. The optical delay element delays the second optical signal to generate a fourth optical signal. The second optical splitter splits a signal representative of the fourth optical signal to generate fifth and sixth optical signals. The first photo detector receives the third optical signal via a first optical path, has an anode terminal coupled to an output terminal of the detector and a cathode terminal coupled to a first supply voltage. The second photo detector receives the sixth optical signal via a second optical path, has an anode terminal coupled to a second supply voltage and a cathode terminal coupled to the output terminal of the detector.

Self-equalizing photo detector

An electro-optical oscillator includes, in part, a modulator, a signal splitter, N photodiodes with N being an integer greater than one, a signal combiner, and a filter. The modulator modulates an optical signal in accordance with a feedback signal. The splitter splits the modulated optical signal into N optical signals each delivered to a different one of N photo-diodes. Each of the N photo-diodes converts the optical signal it receives to a current signal. The signal combiner combines the N current signals received from the N photo-diodes to generate a combined current signal. The filter filters the combined current signal and generates the feedback signal. The electro-optical oscillator optionally includes, in part, N variable optical gain/attenuation components each amplifying/attenuating a different one of the N optical signals generated by the splitter.

Amplification-free electro-optical oscillator

A multi-port radiator radiates electromagnetic signal in response to a beat frequency of a pair of optical signals. The radiator includes a multitude of optical paths each carrying an optical signal having first and second wavelengths. A multitude of frequency conversion elements convert the optical signals to electrical signals and deliver them to the radiator's multiple ports. The frequency of the electrical signals, and hence the frequency of the electromagnetic wave, is defined by the difference between the first and second wavelengths. The phases of the optical signals received by the frequency conversion elements are shifted with respect to one another. Optionally, the difference between the phases of the optical signals travelling through each pair of adjacent paths is 90&#xb0;. The first and second wavelengths are generated by a pair of optical sources and are optionally modulated before being combined and delivered to the optical paths.

Optically driven active radiator

A sensor includes, in part, a multitude of splitters/couplers and optical couplers. One of the splitter/couplers splits an incoming optical signal into first and second optical signals. A first optical coupler includes, in part, a through path receiving the first signal, a coupled path, and an exposure window receiving a sample undergoing sensing by the sensor. The second optical coupler includes, in part, a through path receiving the second signal, and a coupled path. A first output port of the sensor supplies the optical signal travelling in the through path of the first optical coupler. A second splitter/coupler combines the optical signals travelling in the coupled paths of the first and second optical couplers to generate a second output signal delivered to a second output port. An optional third output port supplies the optical signal travelling in the through path of the second optical coupler.

Integrated wide target range optical coupling-based mach-zehnder sensor

An integrated optical linewidth reduction system detects/estimates the phase noise of an incoming optical signal and subtracts the detected phase noise from the phase noise of the incoming signal. A first coupler/splitter of the linewidth reduction system may split the incoming signal into first and second optical signals travelling through first and second optical paths. A second coupler/splitter may split the second optical signal into third and fourth optical signals travelling through third and fourth optical paths. The third optical path has a longer propagation delay than the fourth optical path. Two different coupling ratios of the third and fourth optical signals are used to generate an electrical signal representative of the phase noise of the incoming signal. A phase detector/estimator estimates the phase noise from the electrical signal. A phase modulator subtracts the detected/estimated phase noise from the phase noise of the incoming signal.

Integrated light source independent linewidth reduction

An integrated optical linewidth reduction system includes a phase modulator adapted to modulate the phase of an incoming optical signal in response to a feedback control signal defined by a first electrical signal. The phase modulator is further adapted to generate a first optical signal travelling through a first optical path. The first electrical signal is representative of a phase noise of the first optical signal. An optical linewidth of the first optical signal is less than an optical linewidth of the incoming optical signal.

Integrated light source independent linewidth reduction of lasers using electro-optical feedback techniques

An integrated optical phased array includes an input channel receiving an optical input signal, and a multitude of signal processing channels each adapted to supply an associated optical output signal along a first axis in response to the input signal. Each signal processing channel includes, in part, a phase modulator adapted to modulate the phase of the signal travelling through the channel, thereby to control or steer the output signal of the phased array. Each channel optionally includes first and second photo detection circuits respectively generating first and second detection signals. The first and second detection signals in each channel may be used to modulate the amplitude and/or phase of the output signal of that channel thereby to control and steer the output signal of the phased array.

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Pasadena, CA, United States of America

Firooz Aflatouni