Tian Zhang

Dynamically tunable plasmon induced absorption in graphene-assisted metallodielectric grating

The dynamically tunable plasmon induced absorption (PIA) effect is demonstrated in a graphene-assisted metallodielectric grating structure. Two methods are employed to achieve the tunable PIA effect in the mid-infrared region: one is based on controlling the chemical potential of graphene by adjusting the gate voltage, the other is related to varying the refractive index of interlayer. Our calculated results reveal that high tunability in amplitude and bandwidth of the PIA effect can be achieved by using the above-mentioned methods. Compared with previous results, our scheme is much easier to fabricate and has significant applications in modulators, absorbers and sensors.

Tunable Plasmon Induced Transparency in a Metallodielectric Grating Coupled With Graphene Metamaterials

A novel metallodielectric grating coupled with graphene metamaterials (MGCGM) structure is proposed to achieve the tunable plasmon induced transparency (PIT) effect. Two different mechanisms are employed to explain the PIT effect in the reflection spectrum: one is originated from the destructive interference between graphene plasmonic modes and the hybrid mode in the dielectric layer, the other is related to the absorption of the graphene surface plasmons. The simulated results indicate high tunability in the amplitude and the operating wavelength of the PIT effect can be obtained by controlling the Fermi levels of graphene ribbons. Besides, double PITs are demonstrated in this scheme by altering the occupation ratio of the graphene-based ribbon grating. Compared with previous reports, the MGCGM structure is much easier to fabricate and the tunable PIT effect has significant applications in optical modulator, switching, absorber, sensor, slow light, etc.

Supermode noise suppression with mutual injection locking for coupled optoelectronic oscillator

The coupled optoelectronic oscillator (COEO) is typically used to generate high frequency spectrally pure microwave signal with serious sidemodes noise. We propose and experimentally demonstrate a simple scheme for supermode suppression with mutual injection locking between the COEO (master oscillator with multi-modes oscillation) and the embedded free-running oscillator (slave oscillator with single-mode oscillation). The master and slave oscillators share the same electrical feedback path, which means that the mutually injection-locked COEO brings no additional hardware complexity. Owing to the mode matching and mutually injection locking effect, 9.999 GHz signal has been successfully obtained by the mutually injection-locked COEO with the phase noise about -117 dBc/Hz at 10 kHz offset frequency. Besides, the supermode noise can be significantly suppressed more than 50 dB to below -120 dBc.

Spurious Suppression in Millimeter-Wave OEO With a High-

A millimeter-wave optoelectronic oscillator with low phase noise and low spurs employing ultrahigh <inline-formula> <tex-math notation=LaTeX>

Q

Q

Optoelectronic Filter

</tex-math></inline-formula> optoelectronic hybrid band-pass filter is proposed. The 1-MHz pass-band filter in 29.99 GHz with <inline-formula> <tex-math notation=LaTeX>

Generation and stabilization of millimeter-wave signal employing frequency-quadrupling phase-locked optoelectronic oscillator

Q

Photonic generation of low phase noise millimeter-wave signal based on an ultrahigh Q optoelectronic hybrid bandpass filter

</tex-math></inline-formula> value of 30000 has been demonstrated. Based on this ultranarrow band-pass filter, a 29.99-GHz millimeter-wave signal with the spurious suppression ratio more than 83 dB is successfully generated. Besides, the single-sideband phase noise is about −113 dBc/Hz at 10-kHz offset frequency.

Frequency quadrupling microwave signal generation based on an optoelectronic oscillator with low phase noise

A novel scheme for the generation and stabilization of the millimeter-wave (mmW) signal is theoretically analyzed and experimentally demonstrated. By using the microwave photonics frequency-quadrupling technology and phase-locked optoelectronic oscillator, we generate the millimeter-wave signal with low phase noise and high stability without the frequency limitation of the electrical phase detector and the voltage-controlled microwave phase shifter. Finally, a 40-GHz mmW signal with the stability of 1.38 × 10−12 at the average time of 100 s is generated. The spurious suppression ratio reaches 97 dB, and the measured single-sideband phase noise is lower than -103 dBc/Hz at 10-kHz offset frequency.

Triple band frequency generator based on an optoelectronic oscillator with low phase noise

A millimeter-wave (mmW) optoelectronic oscillator employing ultra-high Q optoelectronic hybrid bandpass filter is proposed. The novel filter with Q value of 30000, bandwidth of 1 MHz and centre frequency of 29.99 GHz has been demonstrated. Based on this ultra-narrow bandpass filter, a 29.99 GHz millimetre-wave signal is successfully generated with the single-sideband phase noise about −113 dBc/Hz at 10 kHz frequency offset. Besides, the measurement results show that the spurs in the mmW oscillator has been suppressed effectively, and the spurious suppression ratio reaches more than 83 dBc.