Researchers at the University of Texas at Austin have developed a hybrid nanomaterial capable of writing, erasing and rewriting optical components. The researchers believe that this nanomaterial and development techniques could be used to create a new generation of optical chips and circuits. In research published in the journal Nano Letters, the Texas team describes how they created their new hybrid nanomaterial by starting from a plasmonic surface. Surface plasmon photonics is the study of the electron density oscillations that occur when photons strike metal surfaces. These wave-like oscillating electrons are called surface plasmons.

In this case, the metal surface consists of aluminum nanoparticles covered with a polymer layer embedded with photosensitive characteristic molecules.

These photochromic molecules are capable of quantum interactions with light, making them transparent or opaque. In the photonic circuit created by the Texas researchers, a metal plasmonic surface and a photochromic molecule represent two quantum systems. In this design, the interaction or coupling between the two quantum systems is very strong. By exploiting these phenomena, the researchers created a waveguide that can control the direction of light, critical to the design of integrated photonic circuits.

The researchers first created their waveguides in nanomaterials using a green laser. They were then able to erase the waveguide using UV light, and then they used a green laser to rewrite the waveguide pattern. The research team believes that this is how humans have since mastered the ability to rewrite waveguides using all-optical techniques.

"In our work, we used hybrid plasmonic waveguides as one quantum system and added molecules to polymers as a second quantum system," Linhan Lin, one of the study's co-authors, said in explained in an email interview with IEEE Spectrum. “Once the strong coupling between these two quantum systems occurs, we can change the resonant frequency of the hybrid plasmonic waveguide in two different new directions simply by irradiating the sample with UV light. ”

According to Lin, the moment the sample is irradiated with UV light, the hybrid plasmonic waveguide fails to work at that resonant frequency, or to put it another way, the waveguide is erased. Once the green laser is irradiated on the sample (the molecule becomes transparent), the resonant frequency will return to its original value. "Through that approach, we got how the waveguide works, so we say we created the waveguide," Lin added.

Of course, the concept of this rewritable optical system is not entirely new; it is based on optical storage media such as CDs and DVDs. However, CDs and DVDs require bulky light sources, optical media, and photodetectors to work. The advantage of the rewritable integrated photonic circuit developed here is that it can be applied to 2-D materials.

“In order to develop rewritable integrated nanophotonic circuits, one needs to be able to confine light in a two-dimensional (2-D) plane, where light can travel long distances in the plane and in the direction of its propagation, Amplitude, frequency and phase were arbitrarily controlled," Yuebing Zheng, a professor at the University of Texas who led the study, said in an interview. “Our material is a hybrid that enables the development of rewritable integrated nanophotonic circuits. “

Some engineering applications need to wait until these rewritable integrated nanophotonic circuits are mature. Taking the technology beyond the lab requires improving the stability of the rewritable device while extending its lifespan, Lin explained. In addition, there is a need to match the operating frequency of the hybrid plasmonic waveguide to the on-chip communication frequency.

Zeng added: "Our goal is to develop rewritable optical components beyond waveguides, which will lead to rewritable optical filters, channel drop filters, delay lines, sensors, lasers, modulators, dispersion compensation Appearance of devices, etc. These are key components of future photonic integrated circuits. “