Microheater

About: Microheater is a research topic. Over the lifetime, 814 publications have been published within this topic receiving 12478 citations.

A loss tunable long-period fiber gratings on corrugated silicon with on-chip microheater and temperature sensor

Abstract: In summary, we report a strain induced long period grating (LPG) created by bonding an etched single mode fibre (SMF) onto a corrugated Si fixture with on-chip heater and temperature sensor. The loss of the LPG can be tuned electrically through the microheater current and monitored simultaneously. The use of Si fixture lends itself to easy integration of microheater and other cascaded filter structure. The results may be useful for dynamic spectral shaping in DWDM networks.

Strategy for Low‐Loss Optical Devices When Using High‐Loss Materials

Abstract: Material loss, especially in metal and 2D materials, is the bottleneck for high‐performance integrated optical devices. Here, a novel concept by utilizing the high‐loss materials in a non‐Hermitian system instead of avoiding the loss materials. It is theoretically analyzed how the complex refractive index affects the loss of optical devices based on a two‐waveguide‐coupled non‐Hermitian system. The results reveal that the loss of optical devices can be improved by increasing the loss of materials or the difference in real refractive indexes. It is experimentally verified that a high loss material can be placed close to the optical waveguide without introducing non‐negligible loss to the optical devices, by demonstrating a thermo‐optic phase shifter with a metallic heater placed very close to the silicon waveguide. As a result, the insertion loss is only 0.1 dB for the 100 μm long heater with a gap of 400 nm, and the largest bandwidth for the metallic heater reaches up to 280 kHz. The finding offers a way to realize high‐performance optical devices with high‐loss materials, contributing to the practical applications of strongly absorbing materials based on non‐Hermitian optics.

Demonstration of green and UV wavelength high Q aluminum nitride on sapphire microring resonators integrated with microheaters

Abstract: We demonstrate a high Q aluminum nitride (AlN) on sapphire microring resonators at green (532 nm) and ultraviolet (UV) (369.5 nm), which are two important wavelengths for sensing and quantum information processing. The quality factors (Q) of these resonators are characterized using integrated microheaters and based on thermo-optic resonance sweeping around those wavelengths for which tunable lasers are typically less available. We measure a record of high intrinsic Q of 147 000 with a propagation loss of 7.3 dB/cm at 532 nm wavelength, and an intrinsic Q of 25 500 with a propagation loss of 60.4 dB/cm at UV 369.5 nm wavelength. We also investigate the thermal crosstalk between the adjacent resonators when temperature change is applied by the microheater of one of the resonators on the same chip. A large thermal crosstalk and resonance shift are observed on other microring resonators even at millimeter(s) distance away from a microheater. This study provides further insight on the functionalities and capabilities of this promising integrated photonic platform for the ultraviolet (UV) and visible range.

Design and Thermal Analysis of Flexible Microheaters

Abstract: With the development of flexible electronics, flexible microheaters have been applied in many areas. Low power consumption and fast response microheaters have attracted much attention. In this work, systematic thermal and mechanical analyses were conducted for a kind of flexible microheater with two different wire structures. The microheater consisted of polyethylene terephthalate (PET) substrate and copper electric wire with graphene thin film as the middle layer. The steady-state average temperature and heating efficiency for the two structures were compared and it was shown that the S-shaped wire structure was better for voltage-controlled microheater other than circular-shaped structure. In addition, the maximum thermal stress for both structures was from the boundary of microheaters, which indicated that not only the wire structure but also the shape of micro heaters should be considered to reduce the damage caused by thermal stress. The influence resulting from the thickness of graphene thin film also has been discussed. In all, the heating efficiency for flexible microheaters can be up to 135 °C/W. With the proposed PID voltage control system, the response time for the designed microheater was less than 10 s. Moreover, a feasible fabrication process flow for these proposed structures combing thermal analysis results in this work can provide some clues for flexible microheaters design and fabrication in other application areas.

Heat Transfer and Bubble Detachment in Subcooled Pool Boiling From a Microheater Array Under the Effect of a Nonuniform Electric Field

Abstract: The effects of a nonuniform electric field on vapor bubble detachment and heat transfer rate were studied in pool boiling at different subcooled conditions for various wall temperatures. Dielectric fluid (FC-72) was used as the working fluid at 1 atm at earth gravity with two extreme gas concentration levels. An array of 3×3 independently controlled microheaters each 0.7×0.7 mm2 in size were maintained at constant temperature using electronic feedback loops, enabling the heat transfer from each heater to be determined. An electric field was applied between the horizontal upward facing microheater array, which was grounded, and a spherical, off-axis top electrode. Boiling heat transfer results with and without the electric field are presented in this study. Without the electric field, a single large “primary” bubble was observed to form due to the coalescence of the individual “satellite” bubbles which nucleated directly from each single heater array. Before its detachment, a dry spot formed underneath this primary bubble resulted in a reduction in heat transfer. With the electric field applied, three or more small “secondary” bubbles that nucleated and grew more rapidly and detached more frequently were observed. Due to the nonuniformity of the electric field, bubbles moved away from the top electrode (into the weaker region of the electric field) during their development. Higher overall heat transfer rates were measured from the heater array. In addition, the bubble behavior showed agreement with our previous investigation of injecting air bubbles into a stagnant, isothermal liquid through orifices.Copyright © 2007 by ASME