All-Optical Switching Demonstrated with Photoactive Yellow Protein Films.

Dániel Petrovszki,Szilvia Krekic,András Dér,Zsuzsanna Heiner,Sándor Valkai

doi:10.3390/bios11110432

Abstract

Integrated optics (IO) is a field of photonics which focuses on manufacturing circuits similar to those in integrated electronics, but that work on an optical basis to establish means of faster data transfer and processing. Currently, the biggest task in IO is finding or manufacturing materials with the proper nonlinear optical characteristics to implement as active components in IO circuits. Using biological materials in IO has recently been proposed, the first material to be investigated for this purpose being the protein bacteriorhodopsin; however, since then, other proteins have also been considered, such as the photoactive yellow protein (PYP). In our current work, we directly demonstrate the all-optical switching capabilities of PYP films combined with an IO Mach–Zehnder interferometer (MZI) for the first time. By exploiting photoreactions in the reaction cycle of PYP, we also show how a combination of exciting light beams can introduce an extra degree of freedom to control the operation of the device. Based on our results, we discuss how the special advantages of PYP can be utilized in future IO applications.

Highlights

Integrated optics (IO) is a new alternative method of information transfer analogous to integrated electronics; the speed of the system at hand is dependent on the nonlinear optical (NLO) material that is applied as the active element of the IO circuit.Several materials are being developed and used in hybrid systems—mostly nonlinear crystals with π-conjugated electron systems [1,2]
Since the results of the present paper prove that refractive index changes associated with the pG to pB transition are sufficient for integrated optical switching, it can be safely stated that it should be true for the pG to ES transition, which takes place on the femtosecond time scale, similar to the bR-I transition of bacteriorhodopsin [7]
Our results demonstrate that dried films of photoactive yellow protein (PYP) can be used for all-optical IO switching because of the favorable nonlinear optical properties of the protein film

Summary

Introduction

Several materials are being developed and used in hybrid systems—mostly nonlinear crystals with π-conjugated electron systems [1,2]. It is among the long-term goals in optical telecommunication to find proper NLO materials that make possible all-optical IO switching at the proper efficiencies and speeds. It was shown that (slow) spectral changes accompanying the photocycle of the chromoprotein bacteriorhodopsin (bR) are sufficient to achieve IO switching [4,5,6], making bR a promising candidate for IO applications. It was demonstrated that the primary events of the bR photocycle allow for ultrafast (sub-picosecond) switching as well [7]

Methods

Results

Discussion

Conclusion