The second harmonic of the 842-nm output of a GaAlAs diode laser is generated in a KNbO(3) crystal in a resonant, external ring cavity. The diode laser is optically stabilized to the ring cavity through feedback from the counterpropagating fundamental wave, which is weakly excited in the resonator. We have produced 6.7 mW of tunable, narrowband radiation at 421 nm and have used that light to pe...

This paper presents a novel three-dimensional active frequency selective surfaces loading a varactor diode to achieve electrically controllable, by loading different values of paranoid voltage to control the variable capacitance diode. Simulation results show that the structure has excellent resonant characteristics in the range of 3.34GHz-1.59GHz, and has certain sensitivity for the change of ...

We demonstrate a spin diode consisting of a semiconductor-free nanoscale Fe/MgO-based double tunnel junction. The device exhibits a near perfect spin-valve effect combined with a strong diode effect. The mechanism consistent with our data is resonant tunneling through discrete states in the middle ferromagnetic layer sandwiched by tunnel barriers of different spin-dependent transparency. The ob...

The concept of on-chip double-resonant-tunneling-diode (RTD) patch-antenna oscillator has the virtues compactness, simplicity, high isolation from external circuitry, and increased output power. Relying on this concept, we demonstrate an order magnitude increase in power compared to previous reports RTD oscillators: 10 ?W at fundamental frequency 525 GHz 70 330 GHz. Estimates show that signific...

We predict and analyse a novel spin filter in semiconducting carbon nanotubes. By using local electrostatic gates, the conduction and valence bands can be modulated to form a double-barrier structure. The confined region below the valence band defines a Zener quantum dot, which exhibits resonant tunnelling. The resonances split in a magnetic field to make a bipolar spin filter for applications ...