ZnO nanorods for efficient third harmonic UV generation

Susanta Kumar Das,Ciarán Gray,Prasanta Kumar Das,Enda Mcglynn,Ruediger Grunwald,Frank Güell

doi:10.1364/ome.4.000701

Abstract

ZnO nanorods grown by both high temperature vapour phase transport and low temperature chemical bath deposition are very promising sources for UV third harmonic generation. Material grown by both methods show comparable efficiencies, in both cases an order of magnitude higher than surface third harmonic generation at the quartz-air interface of a bare quartz substrate. This result is in stark contrast to the linear optical properties of ZnO nanorods grown by these two methods, which show vastly different PL efficiencies. The third harmonic generated signal is analysed using intensity dependent measurements and interferometric frequency resolved optical gating, allowing extraction of the laser pulse parameters. The comparable levels of efficiency of ZnO grown by these very different methods as sources for third harmonic UV generation provides a broad suite of possible growth methods to suit various substrates, coverage and scalability requirements. Potential application areas range from interferometric frequency resolved optical gating characterization of few cycle fs pulses to single cell UV irradiation for biophysical studies.

Highlights

ZnO nanostructures offer an exceptionally interesting and broad range of nanomorphologies and growth methods, with various advantages and disadvantages in terms of potential applications [1]
In this work we report studies of Third harmonic generation (THG) by ZnO nanorod samples grown by both vapour phase transport (VPT) and chemical bath deposition (CBD)
We characterize the THG generated by both sample types using both intensity dependence and interferometric frequency resolved optical gating measurements, and extract the laser pulse parameters for situations of both high and low pulse chirp

Summary

Introduction

ZnO nanostructures offer an exceptionally interesting and broad range of nanomorphologies and growth methods, with various advantages and disadvantages in terms of potential applications [1]. Trade-offs in terms of linear optical properties and scaleability are inherent in the different growth methods of ZnO nanostructures. Further studies of frequency conversion are important because UV light generation via efficient THG in ZnO nanostructures offers many possible applications. In this work we report studies of THG by ZnO nanorod samples grown by both VPT and CBD. We characterize the THG generated by both sample types using both intensity dependence and interferometric frequency resolved optical gating (iFROG) measurements, and extract the laser pulse parameters for situations of both high and low pulse chirp. We conclude that ZnO nanomaterials of these types yield faithful pulse characterization for pulses of original widths < 10 fs and efficient THG, and are excellent prospects for the application areas mentioned above

Experimental details

Results and discussion

Conclusions