Mid-infrared Integrated Electro-optic Modulator Operating up to 225 MHz between 6.4 and 10.7 μm Wavelength

Abstract

Mid-infrared spectroscopy is essential for identifying molecular species, while related electro-optic modulators are crucial for signal-to-noise enhancement via synchronous detection. Therefore, the development of integrated modulators is expected to have a major impact in compact and widespread sensing applications. In this work, we experimentally demonstrate a broadband integrated electro-optic modulator, based on a graded-index SiGe photonics platform and free-carrier plasma dispersion effect. Optical modulation is reported from 6.4 to 10.7 μm wavelength, showing an operational frequency up to 225 MHz. These results pave the way for the development of multimolecule on-chip spectroscopic systems, operating at the longest mid-infrared wavelengths.

Room Temperature‐Integrated Photodetector between 5 μm and 8 μm Wavelength

“…Thus, a vertical diode is obtained, as the top contact is expected to feature a Schottky behavior, while the bottom contact on highly n‐doped Si is expected to be ohmic. [ 3 ] The electrodes have been designed to ensure a characteristic impedance of the line around 50 Ω with a reduced radio frequency (RF) propagation loss. The main parameters for the optimization are the width of the signal line path and the gap between the signal and ground pads.…”

“…From this measurement, a Schottky barrier height of 0.58 eV can be deduced, with an ideality factor of 1.44, which is close to similar devices exploiting the same epitaxial growth. [ 3 ] From the derivative of the I – V curve in the injection regime, it is possible to estimate a serial resistance of 2.5 Ω for the 1.7 mm‐long diode.…”

“…This so-called molecular fingerprint region can, hence, be exploited to detect small traces of hazardous and toxic substances in a large variety of applications including environmental monitoring, hazard detection, industrial process control, or medical diagnosis. [1][2][3] A challenging task is to make mid-IR spectroscopy accessible in remote areas, driving the development of compact and cost-effective solutions to replace table-top systems. The development of mid-IR photonic circuits that integrate complete optical functions has witnessed a burst of research activity in the recent years.…”

“…[14] As a next step to achieve a complete mid-IR photonic platform, active devices are required. While electrically driven integrated optical modulator has been demonstrated recently, [3] this work reports the first integrated photodetector (PD) operating at room temperature in a wide range in the mid-IR, from 5 to 8 μm wavelength. DOI: 10.1002/adpr.202200237 Mid-infrared (mid-IR) optics has a great importance for a large number of applications in sensing, imaging, or even telecommunication.…”

“…[ 14 ] As a next step to achieve a complete mid‐IR photonic platform, active devices are required. While electrically driven integrated optical modulator has been demonstrated recently, [ 3 ] this work reports the first integrated photodetector (PD) operating at room temperature in a wide range in the mid‐IR, from 5 to 8 μm wavelength.…”