Ultracompact on-chip photothermal power monitor based on silicon hybrid plasmonic waveguides

Abstract

Abstract:We propose and demonstrate an ultracompact on-chip photothermal power monitor based on a silicon hybrid plasmonic waveguide (HPWG), which consists of a metal strip, a silicon core, and a silicon oxide (SiO 2 ) insulator layer between them. When light injected to an HPWG is absorbed by the metal strip, the temperature increases and the resistance of the metal strip changes accordingly due to the photothermal and thermal resistance effects of the metal. Therefore, the optical power variation can be monitored by measuring the resistance of the metal strip on the HPWG. To obtain the electrical signal for the resistance measurement conveniently, a Wheatstone bridge circuit is monolithically integrated with the HPWG on the same chip. As the HPWG has nanoscale light confinement, the present power monitor is as short as ~ 3 μm, which is the smallest photothermal power monitor reported until now. The compactness helps to improve the thermal efficiency and the response speed. For the present power monitor fabricated with simple fabrication processes, the measured responsivity is as high as about 17.7 mV/mW at a bias voltage of 2 V and the power dynamic range is as large as 35 dB.

Utilization of Field Enhancement in Plasmonic Waveguides for Subwavelength Light-Guiding, Polarization Handling, Heating, and Optical Sensing

“…Traditional silicon photonic devices with heating/thermal effects usually have a relatively large volume, which leads to bottlenecks in the performance and power consumption. The hybrid nanoplasmonic waveguide, with a very strong confinement of the optical field, provides a possible way to enhance the thermal-optical effect for functionality devices [ 107 , 108 ].…”

“…In Reference [ 108 ], a photo-thermal detector is proposed for the first time by using a hybrid nanoplasmonic waveguide, as shown in Figure 12 a. In this design, the incident TM-polarized light guided by a silicon nanowire is incident to the hybrid plasmonic waveguide section and absorbed by the metal strip atop, which results in a temperature increase.…”

“… ( a ) Configuration of the photo-thermal detector based on a silicon hybrid plasmonic waveguide; ( b ) The optical field distribution of the silicon hybrid plasmonic waveguide with a core width w = 300 nm @ λ = 3.39 μm; ( c ) The temperature profile of the silicon hybrid plasmonic waveguide when 1 mW power is applied in the metal strip; ( d ) The maximal temperature in the metal strip as the input power varies; ( e ) The temporal response of the temperature of the metal strip with an applied power of 1 mW [ 108 ]. …”

Utilization of thermal effects for silicon photonics

“…An integrated power monitor with a long-range surface plasmonic waveguide on silicon was reported [17], and the responsivity is about 0.15mV/mW at the wavelength of 1550nm with a active length as long as 1 mm. Recently, in [18] we proposed a long-wave photodetector with a silicon hybrid plasmonic waveguide (HPW). The reason for considering the longwave range in our case is that people have already developed very excellent photodetectors on silicon for the short wavelength from visible light to the near-infrared light.…”

“…An integrated power monitor with a long-range surface plasmonic waveguide on silicon was reported [17], and the responsivity is about 0.15mV/mW with a active length as long as 1 mm. In [18], we proposed a long-wave photodetector with a silicon hybrid plasmonic waveguide (HPW), and the theoretical responsivity of the proposed photodetector with a footprint of 10 μm×300 nm is as high as 74mV/mW. In addition to metal heaters, more recently graphene is also an excellent candidate for the thermal management of silicon photonic devices because of its high intrinsic thermal conductivity as well as electrical conductivity [19].…”