In this proposal, we discuss a thin film fabrication process designed for solar sailing. Solar sailing is an emerging in-space propulsion method that enables space exploration to be time efficient and low cost. However, to realize fast-transit in solar sailing, lightweight and solar reflective thin film materials are needed. Here we present a fabrication process that enables specular reflective metal coating on top of a freestanding, ultrathin carbon nanotube thin film. The process is scalable, enabling large area fabrication. We demonstrate a centimeter scale freestanding sample. The optical and thermal characteristics of the sample are measured.

Bragg mirrors play an essential role in various optical and photonic devices. The fabrication of Bragg mirrors is mainly done by physical and chemical vapor deposition, which are costly and do not allow for lateral patterning. Here, we demonstrate a versatile and straightforward method to realize the fabrication of Bragg mirrors by fully inkjet printing using a commercial desktop printer. The reflectance peaks of the Bragg mirrors reach 99% with ten uniform bilayers. The central wavelength of the Bragg mirrors is tuned by adjusting printing parameters. With our method, laterally-patterned Bragg mirrors are successfully printed on large and flexible foils.

The development of silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) electro-optic modulators in the 2010s has enabled the large electro-optic (EO) performance of organic chromophores to be leveraged for high-performance photonic components capable of integration with CMOS electronics. Recent improvements in theory-aided design and materials performance have enabled large increases in both electro-optic performance and materials stability. We report on the implications of these developments for hybrid device performance, manufacturability, processing, and packaging, as well as potential new directions for increasingly scalable fabrication of hybrid electro-optic devices for classical and quantum communications and computing applications.

Dielectric metasurfaces working at visible frequencies have been steadily investigated to realize practical flat optical components. However, recently investigated dielectrics, TiO2 and GaN suffer high fabrication costs since a precursor of TiO2 is expensive, and GaN requires two-step etching process. Here, this work suggests optical-loss-suppressed hydrogenated amorphous silicon (a-Si:H) for functional metasurfaces. Optical losses in the visible frequencies are manipulated by adjusting deposition conditions of plasma-enhanced chemical vapor deposition. Optical properties of a-Si:H are optimized for geometric metasurfaces, and it exhibits a high refractive index over 3.0 with low extinction coefficient (<0.1). Using them, highly efficient beam-steering metasurfaces, encapsulated metalenses, and bright structural coloration has been demonstrated. Considering that our manipulation efficiency approaches 42%, 65%, and 75% at the wavelength of 450, 532, 635 nm, it will be dominant materials for a functional photonic platform with low-fabrication costs.

Single mode emission is one of the crucial requirements for Quantum Cascade Lasers (QCLs), which are compact laser sources of infrared radiation in the mid-IR range (3–20 micrometers) and in the THz range (1–5 THz). This feature is particularly important in all spectroscopic applications such as industrial process monitoring, remote sensing, breath analysis for medical diagnostic or industrial process monitoring. In this paper, we have proposed a modified approach to coupled cavity QCLs, based on multisection (three section) coupled cavity QCLs. The range of spectral tuning is very important from the point of view of applications in optical sensing techniques based on the intrapulse tuning of the laser emission. We have designed and fabricated 3-section CC QCLs characterized by intrapulse wavelength tuning of 2.8 cm-1, obtained for 2 mirosecond pulse width. The device operates above room temperature. The improvement of the spectral tuning of 3-section device is compared to 2-section laser. The third section improved significantly the performance of the laser in terms of single mode intrapulse wavelength tuning.

Improving the heat dissipation in Quantum Cascade Lasers (QCLs) is important from the point of view of a growing number of their applications, which require better performance. In this paper, we propose and experimentally demonstrate the possibility of a significant reduction of Active Region (AR) temperature without sophisticated and fabrication-intensive means. We have examined the influence of electroplated gold thickness on thermal and electro-optical properties of InP-based QCLs. Numerical modeling, that we have performed, predicts a significant reduction of the laser core temperature of epi-side up mounted ridge waveguide QCLs with increased thickness of electroplated gold. Predictions of the numerical model have been confirmed experimentally by means of electro-optical, spectral, and thermal characterization.

Inverse opal (IO) photonic semiconductors are promising materials for photocatalysis, thanks to their slow photon properties that increase light harvesting. Here, we report, in IO TiO2-BiVO4 photonic structures, the ability not only to generate slow photons in the visible range but also to tune their frequencies and transfer their energy. Angle-resolved photocatalytic experiments revealed a 70% increase in activity in all IO structures compared to non-IO compact films and a further 20% increase when the slow photons were accurately tuned to BiVO4 electronic absorption. The synthesis and tuning strategies presented here can be extended to all solar energy conversion applications.

Biointegrated microlasers can act as highly localized sensors and report minute refractive index changes from within living cells. We previously reported non-obstructive and biointegrated whispering gallery mode nanolasers made from high-index semiconductor materials. Arsenide-free III/V alloys are attractive for this application due to minimal toxicity and high performance at visible wavelengths. Here, the band gaps of GaInP/AlGaInP quantum wells were engineered for absorption and emission at (far)-red wavelengths, allowing sub-pJ pumping at 642 nm and two-photon pumping with lasing thresholds around 80 pJ. This facilitates the wider integration of the nanolaser technology with popular fluorescence and multiphoton microscopy techniques.

Thermal radiation is the most ubiquitous form of heat. Developing new science and technology to dynamically control radiative heat transfer can bring a profound impact on the mitigation of global warming, in which thermal engineering becomes increasingly important. In this talk, I will introduce our recent electrochemically-driven device that can vary the thermal emissivity between 0.07 and 0.92, which serves as a powerful radiative thermal switch to control the heat transfer. The device is water-based, flexible, and non-volatile, which can be used as scalable building envelope thermoregulation to reduce the energy consumption and carbon footprint of space heating and cooling.