Photonics-based microwave frequency mixing provides distinct features in terms of wide frequency coverage, broad instantaneous bandwidth, small frequency-dependent loss, and immunity to electromagnetic interference as compared with its electronic counterpart, which can be a key technical enabler for future broadband and multifunctional RF systems. Herein, all-optical and optoelectronic microwave frequency mixing techniques are reviewed, with an emphasis on the latest advances in photonics-based microwave frequency mixers with improved performance in terms of conversion efficiency, dynamic range, mixing-spur suppression, mixing functionality, and polarization independence. Innovative applications enabled by photonics-based microwave frequency mixers, such as radio-over-fiber communication systems, radar systems, satellite payloads and electronic warfare systems, are also reviewed. In addition, efforts in implementing integrated photonics-based microwave mixers that lead to a dramatic reduction in size, weight, and power consumption are also reviewed.

Photonics-Based Microwave Frequency Mixing: Methodology and Applications

This paper presents a review and discussion of the directly modulated semiconductor lasers and their applications to optical communications and microwave photonics. A detailed and comprehensive demonstration of directly modulated semiconductor lasers from development history to specific techniques on measurement, analysis, and packaging is provided for the first time to the best of our knowledge. A few typical applications based on directly modulated lasers are also illustrated, such as optical fiber communications, free-space optical communications and microwave photonics. Future directions of research are also highlighted.

Directly Modulated Semiconductor Lasers

In the process of stimulated Brillouin scattering (SBS), acoustic waves are generated by the interference of counterpropagating optical waves via electrostriction effect. These acoustic waves not only stimulate the Brillouin scattering process, but can also play a role of moving Bragg reflector for another optical wave when a proper phase-matching condition is satisfied between the interacting optical waves. Brillouin dynamic grating (BDG) represents this secondary role of the acoustic wave, which shows a unique reflection spectrum, called BDG spectrum. The BDG spectrum generally shows higher sensitivity to the change of physical variables, such as temperature and strain than ordinary Brillouin gain spectrum (BGS), and also provides information on the waveguide parameters, such as polarization or modal birefringence with high accuracy. This paper reviews the operation principle of BDG under various conditions and the research progresses on its application to distributed fiber sensors.

Applications of Brillouin Dynamic Grating to Distributed Fiber Sensors

This paper reviews recent progresses on optical arbitrary waveform generation (AWG) techniques, which could be used to break the speed and bandwidth bottlenecks of electronics technologies for waveform generation. The main enabling techniques for optically generating optical and microwave waveforms are introduced and reviewed in this paper, such as wavelength-to-time mapping techniques, space-to-time mapping techniques, temporal pulse shaping (TPS) system, optoelectronics oscillator (OEO), programmable optical filters, optical differentiator and integrator and versatile electro-optic modulation implementations. The main advantages and challenges of these optical AWG techniques are also discussed.

Recent progresses on optical arbitrary waveform generation

Temperature dependencies of the Brillouin dynamic grating (BDG) spectra in polarization-maintaining fibers (PMF's) are rigorously investigated. PANDA fiber, Bow-tie fiber, and PM photonic crystal fiber (PM-PCF) with different parameters are tested in the temperature range of −30 to +150 °C, where the linear and nonlinear temperature dependencies are quantified for each fiber. It is observed that bare PANDA and Bow-tie fibers show similar shape and magnitude of the nonlinear temperature dependence, while the contribution of the acrylate coating appears differently for each fiber. Suppression of the temperature dependence is observed in the PM-PCF, where notable effects of the acrylate coating on the birefringence are observed only below the room temperature. We also present the result of comparative measurement of the polarization beat length using the BDG analysis and the periodic lateral force method, which confirms the validity of the BDG-based birefringence measurement.

Characterization of Nonlinear Temperature Dependence of Brillouin Dynamic Grating Spectra in Polarization-Maintaining Fibers

We report an optical vector network analyzer (OVNA) based on double-sideband (DSB) modulation using a dual-parallel Mach–Zehnder modulator. The device under test (DUT) is measured twice with different modulation schemes. By post-processing the measurement results, the response of the DUT can be obtained accurately. Since DSB modulation is used in our approach, the measurement range is doubled compared with conventional single-sideband (SSB) modulation-based OVNA. Moreover, the measurement accuracy is improved by eliminating the even-order sidebands. The key advantage of the proposed scheme is that the measurement of a DUT with bandpass response can also be simply realized, which is a big challenge for the SSB-based OVNA. The proposed method is theoretically and experimentally demonstrated.

Optical vector network analyzer based on double-sideband modulation.

We first propose a multichannel optical filter with an ultra-narrow 3-dB bandwidth based on sampled Brillouin dynamic gratings (SBDGs). The multichannel optical filter is generated when an optical pulse interfaces with an optical pulse train based on an ordinary stimulated Brillouin scattering (SBS) process in a birefringent optical fiber. Multichannel optical filter based on SBDG is generated with a 3-dB bandwidth from 12.5 MHz to 1 GHz. In addition, a linearly chirped SBDG is proposed to generate multichannel dispersion compensator with a 3-dB bandwidth of 300 MHz and an extremely high dispersion value of 432 ns/nm. The proposed multichannel optical filters have important potential applications in the optical filtering, multichannel dispersion compensation and optical signal processing.

Multichannel optical filters with an ultranarrow bandwidth based on sampled Brillouin dynamic gratings

A laser device frequency stability testing device comprises a first drive circuit, a second drive circuit, a first laser device, a second laser device, an optical fiber coupler, a photoelectric detector, an amplifier, a frequency spectrum analyzer, a computer and an optical spectrum analyzer. The first drive circuit and the second drive circuit respectively comprise a temperature control device. The first drive circuit provides drive control for the first laser device, and the second drive circuit provides drive control for the second laser device. One input end a of the optical fiber coupler is connected with a tail fiber of the first laser device, and the other input end b of the optical fiber coupler is connected with a tail fiber of the second laser device. A tail fiber of the photoelectric detector is connected with one output end c of the optical fiber coupler. The amplifier receives a light intensity voltage signal output by the optical fiber coupler. The frequency spectrum analyzer is connected with the amplifier. The computer receives data of the frequency spectrum analyzer through a GPIB card to conduct data acquisition of a beat frequency signal. The optical spectrum analyzer is connected with the other output end d of the optical fiber coupler.

Laser device frequency stability testing device

The invention provides a stimulated brillouin scattering-based laser device linewidth narrowing device, which comprises a DFB semiconductor laser device, an erbium-doped optical fiber amplifier, a first optical fiber circulator, a brillouin scattering device, a second optical fiber circulator, an optical fiber polarizer, an optical fiber coupler, an erbium-doped optical fiber, a third optical fiber circulator and an optical filter, wherein an input end of the erbium-doped optical fiber amplifier is connected with an output end of the DFB semiconductor laser device; a port 1 of the first optical fiber circulator is connected with the output end of the erbium-doped optical fiber amplifier; one end of the brillouin scattering device is connected with a port 2 of the first optical fiber circulator; the port 1 of the second optical fiber circulator is connected with a port 3 of the first optical fiber circulator; the input end of the optical fiber polarizer is connected with a port 2 of the second optical fiber circulator; the input end of the optical fiber coupler is connected with the output end of the optical fiber polarizer; the port B of the erbium-doped optical fiber is connected with the port 2 of the optical fiber coupler; the port A of the erbium-doped optical fiber is connected with the port 1 of the optical fiber coupler; the port 2 of the third optical fiber circulator is connected with the other end of the brillouin scattering device; and the input end of the optical fiber is connected with the port 3 of the third optical fiber circulator.

Stimulated brillouin scattering-based laser device linewidth narrowing device

we report a 1.3μm 30-GHz directly modulation distributed feed-back laser with narrow linewidth of 130kHz and high side-mode suppression ratio of 52dB. The output power is more than 16mW at 100mA and the input 1-dB compression point is showed with different frequencies.

Guo Jinjin

Papers

Optical vector network analyzer based on double-sideband modulation.

Multichannel optical filters with an ultranarrow bandwidth based on sampled Brillouin dynamic gratings

Laser device frequency stability testing device

Stimulated brillouin scattering-based laser device linewidth narrowing device

30-GHz directly modulation DFB laser with narrow linewidth