Photonic-assisted multiple microwave frequency measurement with improved robustness.

A multiple microwave frequency measurement approach based on frequency-to-time mapping (FTTM) is reported. The FTTM is constructed by optical sideband sweeping and electric-domain intermediate frequency envelope monitoring. Two optimized operations are implemented.

Photonics-Based Simultaneous DFS and AOA Measurement System without Direction Ambiguity.

A novel scheme that can simultaneously measure the Doppler frequency shift (DFS) and angle of arrival (AOA) of microwave signals based on a single photonic system is proposed. At the signal receiving unit (SRU), two echo signals and the reference signal are modulated by a Sagnac loop structure and sent to the central station (CS) for processing. At the CS, two low-frequency electrical signals are generated after polarization control and photoelectric conversion.

Photonic-Assisted Scheme for Simultaneous Self-Interference Cancellation, Fiber Dispersion Immunity, and High-Efficiency Harmonic Down-Conversion.

A photonic approach to the cancellation of self-interference in the optical domain with fiber dispersion immunity and harmonic frequency down-conversion function is proposed based on an integrated, dual-parallel, dual-drive Mach-Zehnder modulator (DP-DMZM). A dual-drive Mach-Zehnder modulator (DMZM) is used as an optical interference canceller, which cancels the self-interference from the impaired signal before fiber transmission to avoid the effect of fiber transmission on the cancellation performance. Another DMZM is used to provide carrier-suppressed, local-oscillation (LO)-modulated, high-order double optical sidebands for harmonic frequency down-conversion to release the strict demand for high-frequency LO sources.

Free Space Measurement Device Independent Quantum Key Distribution with Modulating Retro-Reflectors under Correlated Turbulent Channel.

Modulating retro-reflector (MRR), originally introduced to support laser communication, relieves most of the weight, power, and pointing requirements to the ground station. In this paper, a plug-and-play measurement device independent quantum key distribution (MDI-QKD) scheme with MRR is proposed not only to eliminate detector side channels and allow an untrusted satellite relay between two users, but also to simplify the requirements set-ups in practical flexible moving scenarios. The plug-and-play architecture compensates for the polarization drift during the transmission to provide superior performance in implementing the MDI-QKD on a free-space channel, and the MRR device is adopted to relax the requirements on both communication terminals.

Influence of Source Parameters on the Polarization Properties of Beams for Practical Free-Space Quantum Key Distribution.

Polarization encoding has been extensively used in quantum key distribution (QKD) implementations along free-space links. However, the calculation model to characterize channel transmittance and quantum bit error rate (QBER) for free-space QKD has not been systematically studied. As a result, it is often assumed that misalignment error is equal to a fixed value, which is not theoretically rigorous.

Photonic 2-D angle-of-arrival estimation based on an L-shaped antenna array for an early radar warning receiver.

Early radar warning is a significant step to lessen the fine scanning range of a receiver. The small size two-dimension (2-D) angle-of-arrival (AOA) estimation part with moderate accuracy and sensitivity is important for an early radar warning receiver. In our method, we specially design an L-shaped antenna array (L-sAA) and connect it with dual-polarization binary phase shift keying modulator (DP-BPSKM).

Photonics-based multi-band linearly frequency modulated signal generation and anti-chromatic dispersion transmission.

A photonics-based anti-chromatic dispersion transmission scheme for multi-band linearly frequency modulated (LFM) signals is proposed and experimentally demonstrated. In the central station (CS), the key component is an integrated dual-polarization quadrature phase shift keying (DP-QPSK) modulator, of which the up-arm and down-arm are driven by a microwave reference signal and an intermediate-frequency (IF) LFM signal respectively. By properly adjusting the DP-QPSK modulator, optical frequency comb (OFC) and frequency shift lightwave are generated.

Frequency downconversion with independent multichannel phase shifting and zero-intermediate-frequency receiving based on optical frequency shift and polarization multiplexing.

Photonic microwave frequency downconversion with independent multichannel phase shifting and zero-intermediate-frequency (IF) receiving via an integrated polarization multiplexing dual-parallel Mach-Zehnder modulator (MZM) is proposed. Based on the ideas of optical frequency shift and polarization multiplexing, the radio frequency (RF) signal is frequency downconverted to multichannel IF signals with the phases independently and arbitrarily tuned by adjusting the polarization controllers or even frequency downconverted to baseband directly by choosing two quadrature channels. In the simulation, the gain of our proposed frequency downconversion system is higher than that of the conventional two cascaded MZMs' system, and the phase shift with the range of 360° can be obtained concurrently.

Generation of a frequency-quadrupled phase-coded signal using optical carrier phase shifting and balanced detection.

A novel approach for photonic generation of a frequency-quadrupled phase-coded signal using optical carrier shifting and balanced detection is proposed and demonstrated. The key component of the scheme is an integrated dual-polarization quadrature phase shift-keying (DP-QPSK) modulator. In the modulator, an RF signal is applied to the upper QPSK modulator to generate high-order optical sidebands, while an electrical coding signal is applied to the bottom QPSK modulator to perform optical carrier phase shifting.

Displacement damage in bit error ratio performance of on-off keying, pulse position modulation, differential phase shift keying, and homodyne binary phase-shift keying-based optical intersatellite communication system.

Displacement damage (DD) effect induced bit error ratio (BER) performance degradations in on-off keying (OOK), pulse position modulation (PPM), differential phase-shift keying (DPSK), and homodyne binary phase shift keying (BPSK) based systems were simulated and discussed under 1 MeV neutron irradiation to a total fluence of 1×10  n/cm in this paper. Degradation of main optoelectronic devices included in communication systems were analyzed on the basis of existing experimental data. The system BER degradation was subsequently simulated and the variations of BER with different neutron irradiation location were also achieved.

Broadband linearized analog intersatellite microwave photonic link using a polarization modulator in a Sagnac loop.

A novel orthogonal polarization optical carrier suppression with carrier (OCS+C) modulation and a coherent balanced detection intersatellite microwave photonic link with improved signal-to-noise and distortion ratio (SNDR) is proposed. By bidirectional use of a polarization modulator in a Sagnac loop in conjunction with a polarization beam splitter and two polarization controllers, only the light wave along the clockwise direction is effectively modulated while the counterclockwise light wave is not modulated due to the velocity mismatch, which generates the orthogonal polarization OCS+C modulation signal to mitigate the third-order intermodulation distortion (IMD3) and the signal-amplifier spontaneous emission beating noise. By demultiplexing and adjusting the polarization of the orthogonal polarization OCS+C modulation signal, coherent balanced detection can be realized without a local oscillator signal in the receiver, which suppresses the second-order distortions.

Filterless frequency 12-tupling optical millimeter-wave generation using two cascaded dual-parallel Mach-Zehnder modulators.

A novel frequency 12-tupling optical millimeter-wave (mm-wave) generation using two cascaded dual-parallel Mach-Zehnder modulators (DP-MZMs) without an optical filter is proposed and demonstrated by computer simulation. By properly adjusting the amplitude and phase of radio frequency (RF) driving signal and the direct current (DC) bias points of two DP-MZMs, a 120 GHz mm-wave with an optical sideband suppression ratio (OSSR) of 25.1 dB and a radio frequency spurious suppression ratio (RFSSR) of 19.

Impact of pointing errors on performance of an intersatellite microwave photonics link with an optical preamplifier under dual-tone modulation.

The intersatellite microwave photonics link with an optical preamplifier is affected by third-order intermodulation distortion under dual-tone modulation and pointing errors due to beam wander, which would greatly degrade the link performance. An exact analytical expression for signal-to-noise and distortion ratio (SNDR) is derived considering the signal fade caused by the pointing errors of transceiver. It is shown that, given the desired SNDR and the rms random pointing jitter, an optimum modulation index of Mach-Zehnder modulator exists that minimizes laser output power.

Optimization of an analog intersatellite microwave photonics link with an optical preamplifier.

An exact analytical expression of the signal-to-noise ratio (SNR) for an intersatellite microwave photonics link with an optical preamplifier is derived considering the signal fade caused by the pointing errors of the transceiver, and an optimized model for laser output power and direct current (DC) bias phase shift of the Mach-Zehnder modulator is established. It is shown that, given the desired SNR and the root mean square (rms) random pointing jitter, an optimal DC bias phase shift exists that minimizes laser output power. The effects of the optical preamplifier parameters on the minimum laser output power and optimal DC bias phase shift are also examined.

Optimization of intersatellite microwave photonic links by utilizing an optical preamplifier under dual-tone modulation.

An optical preamplifier is utilized to improve the signal-to-noise and distortion ratio (SNDR) of intersatellite microwave photonic links employing a Mach-Zehnder modulator under dual-tone modulation. The resulting SNDR at an appropriate direct current (DC) bias phase shift is additionally investigated without small-signal approximation in order to optimize the performance of all the links. It is observed that the most limiting factor degrading the SNDR performance is changed, and the fundamental power is seen to increase more compared with the power of third-order intermodulation (IM3) plus noise due to the optical preamplifier.

Laser-jamming effectiveness analysis of combined-fiber lasers for airborne defense systems.

The laser-jamming effectiveness of combined fiber lasers for airborne defense systems is analyzed in detail. Our preliminary experimental results are proof of the concept of getting a high-power laser through a beam combination technique. Based on combined fiber lasers, the jamming effectiveness of four-quadrant guidance and imaging guidance systems are evaluated.