Haiqing Yuan

Surface acoustic wave velocity and electromechanical coupling coefficient of GaN grown on (0001) sapphire by metal-organic vapour phase epitaxy

High-quality and high-resistivity GaN films were grown on (0001) sapphire face by metal-organic vapour phase epitaxy. To measure the surface acoustic wave properties accurately, we deposited metallized interdigital transducers on the GaN surface. The acoustic surface wave velocity and electromechanical coupling coefficient were measured, respectively, to be 5667 m/s and 1.9% by the pulse method.

30-GHz directly modulation DFB laser with narrow linewidth

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.

Frequency-Doubling OEO Using the Polarization Property of LiNbO 3 Modulator

A frequency-doubling optoelectronic oscillator (OEO) has been proposed. In the proposed device, several passive components are introduced into the traditional OEO to handle the polarization state of the laser in the feedback loop. Making use of the polarization dependence of the LiNbO3 intensity modulator, a special double sidebands modulation is implemented where the polarization direction of the optical carrier is orthogonal with that of the first-order sidebands. Two polarizers are used to choose the specific optical components from the modulated light, which ensures that a microwave signal at the second-harmonic frequency outputs from the OEO when the fundamental frequency signal is self-oscillating in the loop. In the experiment, a 20-GHz frequency-doubled signal was generated, whose phase noise performance and immunity to the polarization drift were measured and evaluated.

Microwave packaging for 10-Gb/s EML modulators

A novel microwave packaging technique for 10Gb/s electro-absorption modulator integrated with distributed feedback laser (EML) is presented. The packaging parasitics and intrinsic parasitics are both well considered, and the packaging circuit was synthetically designed to compensate for the intrinsic parasitic of the chip. A butterfly-packaged EML module has been successfully developed to prove that. The small-signal modulation bandwidth of the butterfly-packaged module is about 10 GHz. Optical fiber transmission experiments have shown that the module can be used for 10Gb/s optical transmission system. After transmission through 40km, the power penalty is less than 1 dBm at a bit-error-rate of 10-12.

Three-dimension package design for electro-absorption modulation laser array

We report a new 3-D package design technique in this paper. Based on this technique, a 3-D RF impedance matching circuit used in the packaging of electroabsorption modulation laser (EML) array is achieved, which has the characteristics of low electrical crosstalk and small size. The 3-D package design technique overcomes the limitation of conventional 2-D design technique in which many bonding wires have to be employed. The measurement results demonstrate that the 3-D impedance matching circuit has a transmission bandwidth of 25 GHz and the reflection is suppressed below -10 dB in a wide frequency range. Compared with NTTs schemes, the 3-D impedance matching circuit and the wires in our scheme have a lower electrical crosstalk. A ten-channel EML module is fabricated, employing the above technique, and demonstrated. The module has good frequency characteristics over a bandwidth of 10 GHz. To our knowledge, this is the first time that such a 3-D impedance matching circuit has been reported publicly.

A Widely Tunable Photonic-Assisted Microwave Notch Filter with High Linearity Using a Dual-Parallel Mach—Zehnder Modulator

A widely tunable microwave photonic (MWP) notch filter with high linearity based on a dual-parallel Mach—Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. The motivation of this work lies in the fact that the MWP notch filter previously reported has nonlinear distortions generally induced by the nonlinear property of electro-optic devices. In this scheme, even-order modulated sidebands at the DPMZM output are effectively suppressed by properly adjusting bias voltages of the DPMZM, which are the dominant factor to induce the nonlinear distortions into the MWP notch filter. The proposed scheme is theoretically analyzed and experimentally verified.

Multi-microwave sources generation based on dual optical frequency combs

We proposed a scheme for multi-band microwave sources generation based on dual optical frequency combs (OFCs) in this paper. By optically channelizing the mixed OFCs, the heterodyned electrical signals in different bands can be obtained in different channels. Multiple microwave sources at 2.5GHz, 5GHz, 7.5GHz, 10GHz and 12.5GHz were generated, whose signal to noise ratio (SNR) between 38dB to 49dB in 1.4GHz bandwidth were obtained. The system has potential applications in satellite repeaters.