On-chip Power Monitoring Research Articles

On-Chip Power Monitoring: Leveraging High-Sensitivity Differential Temperature Sensors With Chopper Stabilization and Offset Calibration

On-Chip Power Monitoring: Leveraging High-Sensitivity Differential Temperature Sensors With Chopper Stabilization and Offset Calibration

Monolithically integrated, broadband, high-efficiency silicon nitride-on-silicon waveguide photodetectors in a visible-light integrated photonics platform

Visible and near-infrared spectrum photonic integrated circuits are quickly becoming a key technology to address the scaling challenges in quantum information and biosensing. Thus far, integrated photonic platforms in this spectral range have lacked integrated photodetectors. Here, we report silicon nitride-on-silicon waveguide photodetectors that are monolithically integrated in a visible light photonic platform on silicon. Owing to a leaky-wave silicon nitride-on-silicon design, the devices achieved a high external quantum efficiency of >60% across a record wavelength span from λ ~ 400 nm to ~640 nm, an opto-electronic bandwidth up to 9 GHz, and an avalanche gain-bandwidth product up to 173 ± 30 GHz. As an example, a photodetector was integrated with a wavelength-tunable microring in a single chip for on-chip power monitoring.

Output Power Monitoring of Ultraviolet Light-Emitting Diode via Sapphire Substrate

Ultraviolet (UV) light plays an important role in air/water/surface sterilization now. Maintaining a certain light intensity is often required to attain the targeted effect. In this paper, on-chip power monitoring of a UV-A light-emitting diode (LED) via sapphire substrate is reported. A p–i–n photodiode loop that surrounds the UV-A LED was designed and fabricated to monitor the output power by detecting the scattered light of the LED propagating through the sapphire substrate. No particular waveguide structure or processing parameter control was needed. The monitoring responsivities per unit of surface-emitting power obtained were approximately 21 and 25 mA/W at photodiode biases of 0 and 3 V, respectively. When combined with a transimpedance amplifier, a monitoring responsivity of 1.87 V/mW at zero bias was measured, and a different monitoring responsivity could be customized by adjusting the gain of the transimpedance amplifier. The operation principle of this device might be applicable to UV-B or UV-C LEDs.

On-chip multicomponent system made with vertical structure quantum well diode

A vertical-structure quantum well (QW) diode based monolithic multicomponent system is for the first time implemented by integrating a light-emitting diode (LED), waveguide, and photodiode (PD) on a metal-bonded III-nitride-on-silicon platform. Two identical QW-diodes that are manufactured using all existing standard fabrication processes function as the LED and PD respectively, and waveguides are formed to establish on-chip optical link between the LED and PD. The PD absorbs the light from the adjacent LED coupled through the waveguide to induce a photocurrent that is proportional to the injection current of the LED, leading to an on-chip power monitoring system. One PD can monitor multiple LEDs simultaneously by identifying individual differences of the system from the superimposed signals using signal extraction approach.

On-chip multicomponent system made with an InGaN directional coupler.

An on-chip multicomponent system is implemented on a III-nitride-on-silicon platform by integrating a transmitter, InGaN waveguide, InGaN directional coupler, and receivers onto a single chip. The transmitter and the receiver share an identical InGaN/GaN multiple-quantum-well (MQW) diode structure and are produced by using the same wafer-level process flow. The receiver sensitively responds to the short-wavelength half of the emission spectrum of the transmitter, thus realizing the multicomponent system with the capability for inplane light communication. A SiO2 isolation layer is employed to decrease the p-n junction capacitance, thus improving the modulation rate without modifying the MQW structure. The wire-bonded monolithic multicomponent system experimentally demonstrates inplane data transmission at 80Mbps and spatial light communication at 100Mbps, paving the way for diverse applications from on-chip power monitoring to inplane light communication in the visible light spectrum.

Transferrable monolithic III-nitride photonic circuit for multifunctional optoelectronics

A monolithic III-nitride photonic circuit with integrated functionalities was implemented by integrating multiple components with different functions into a single chip. In particular, the III-nitride-on-silicon platform is used as it integrates a transmitter, a waveguide, and a receiver into a suspended III-nitride membrane via a wafer-level procedure. Here, a 0.8-mm-diameter suspended device architecture is directly transferred from silicon to a foreign substrate by mechanically breaking the support beams. The transferred InGaN/GaN multiple-quantum-well diode (MQW-diode) exhibits a turn-on voltage of 2.8 V with a dominant electroluminescence peak at 453 nm. The transmitter and receiver share an identical InGaN/GaN MQW structure, and the integrated photonic circuit inherently works for on-chip power monitoring and in-plane visible light communication. The wire-bonded monolithic photonic circuit on glass experimentally demonstrates in-plane data transmission at 120 Mb/s, paving the way for diverse applications in intelligent displays, in-plane light communication, flexible optical sensors, and wearable III-nitride optoelectronics.

In-plane visible light communication made with InGaN turning mirror

The refractive index contrast between AlGaN and InGaN leads to the formation of an optically-confined InGaN waveguide structure. Therefore, we propose a simple fabrication procedure to achieve on-chip photonic integration including a light source, waveguide, beam splitter, turning mirror and photodiode on an III-nitride-on-silicon platform. By inserting InGaN/GaN multiple-quantum-well active layer inside the InGaN waveguide, the emitted light is confined and coupled to the light waveguide. The in-plane light propagation that is directly observed due to the visible light emission is manipulated by the beam splitter and turning mirror. The waveguide–splitter–mirror-integrated III-nitride photonic circuit experimentally demonstrates an in-plane data transmission at 50 Mbps using visible light, suggesting its great potential for diverse applications in on-chip power monitoring, high-resolution blue printing and in-plane light communication.

Beyond the Roofline: Cache-Aware Power and Energy-Efficiency Modeling for Multi-Cores

To foster the energy-efficiency in current and future multi-core processors, the benefits and trade-offs of a large set of optimization solutions must be evaluated. For this purpose, it is often crucial to consider how key micro-architecture aspects, such as accessing different memory levels and functional units, affect the attainable power and energy consumption. To ease this process, we propose a set of insightful cache-aware models to characterize the upper-bounds for power, energy and energy-efficiency of modern multi-cores in three different domains of the processor chip: cores, uncore and package. The practical importance of the proposed models is illustrated when optimizing matrix multiplication and deriving a set of power envelopes and energy-efficiency ranges of the micro-architecture for different operating frequencies. The proposed models are experimentally validated on a computing platform with a quad-core Intel 3770K processor by using hardware counters, on-chip power monitoring facilities and assembly micro-benchmarks.

Compact and low-loss asymmetrical multimode interference splitter for power monitoring applications.

This Letter presents a compact and low-loss 1×2 asymmetrical multimode interference (A-MMI) splitter in rib geometry for on-chip power monitoring at 1.55 μm, where a given alteration of the component cavity determines arbitrary values of the output power splitting ratios. The device shows reduced losses (∼0.4-0.8 dB) and robustness across a 40 nm optical bandwidth (1540-1580 nm).