This study describes the design of a resonant tunneling diode (RTD) oscillator (RTD oscillator) with a RTD-gated-graphene-2DEF (two dimensional electron fluid) and demonstrates the functioning of this RTD oscillator through a transmission line simulation model. Impedance of the RTD oscillator changes periodically when physical dimension of the device is of considerable fraction of the electrical wavelength. As long as impedance matching is achieved, the oscillation frequency is not limited by the size of the device. An RTD oscillator with a graphene film and negative differential resistance (NDR) will produce power amplification. The positive electrode of the DC power supply is modified and designed as an antenna. So, the reflected power can also be radiated to increase RTD oscillator output power. The output analysis shows that through the optimization of the antenna structure, it is possible to increase the RTD oscillator output to 22 mW at 1.9 THz and 20 mW at 6.1 THz respectively. Furthermore, the RTD oscillator has the potential to oscillate at 50 THz with a matching antenna.

For the further integration of receivers in multi-color visible light communication systems, a novel color photodetector (PD) was designed and fabricated by using a 40 nm standard complementary metal oxide semiconductor (CMOS) process without any process modifications. The PD consists of CMOS photodiode and two-dimensional (2D) polysilicon subwavelength grating above the photodiode. The 2D polysilicon grating is controlled in structural parameters to realize color filtering, based on guided-mode resonance, for the first time in a standard CMOS process. Here three kinds of color PDs were designed to respond to the three primary colors. The measured results demonstrate that the color PDs exhibit wavelength selectivity in the visible range (400-700 nm) and the maximum peaks in the spectral response curves of them are at 660 nm (red), 585 nm (green) and 465 nm (blue), respectively. In addition, the added 2D polysilicon grating almost does not reduce the responsivity of the photodiodes.

To prepare a desired negative differential resistance (NDR) device by standard complementary-metal-oxide-semiconductor (CMOS) process, a photoelectric dual control NDR device with a PNP bipolar-junction-transistor (BJT) and an NPN BJT was designed and fabricated by using the Si-base standard 0.18 μm CMOS process without any process modification and a special substrate. In order to reduce the valley current under optical control, a metal mask was added to the NDR device. The results show that the device exhibits good NDR characteristics under either voltage-control or photo-control. Under voltage-control, a low volley current (0.23 pA) and a high peak-to-valley current ratio (1.4 × 10 ¹⁰ ) are obtained at less than 1 V. Under photo-control, the two parameters obtained at less than 0.5 V, are 37 nA and 4827, respectively. Also, the device displays fine S-type NDR characteristics and nice maintaining response function under photo-control. These superior photoelectric NDR characteristics endow the device with greatly potential application in the photoelectric logic circuits.

Inspired by the mechanism of visual attentional selection, a color feature selection unit consisting of photoreceptors and an attentional selection circuit (ASC) is presented. The detection and wavelength recognition of trichromatic light are accomplished by the photoreceptors with RGB filters. The ASC, fabricated in a standard CMOS technology, activates the competition among photoreceptors to select the principal color-component feature defined as the attentional focus. The number of focuses and resolution can be changed with a top-down stimulus. Electrical test results show that the ASC can select and interpret the most important color-component feature. In optical tests, the ASC chip-based unit can extract the principal color-component of single-color and dual-color light in real-time to complete color recognition. The percentage ratio between the intensity of stray light relative to the light with maximum intensity is up to 93.58%. And the maximum achievable recognition frame rate is 1 kHz, which is more than one order of magnitude higher than the frequency of the biological vision systems. Besides, the unit's outputs can be transformed into binary codes as labels for color recognition, and the color recognition process does not require the participation of ADC, CPU, and memory, consequently avoiding the von Neumann bottleneck.