Biosensing using photonic crystal nanolasers

PDF / 3,094,963 Bytes
10 Pages / 612 x 792 pts (letter) Page_size
47 Downloads / 220 Views

lasmonics, Photonics, and Metamaterials Prospective Article

Biosensing using photonic crystal nanolasers Toshihiko Baba, Department of Electrical and Computer Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama 240-8501, Japan Address all correspondence to Toshihiko Baba at [email protected] (Received 17 September 2015; accepted 6 November 2015)

Abstract Photonic crystal nanolasers are fabricated and operated simply, and can be applied as disposable sensors for biomedical applications. They are sensitive to the change with environmental index and surface charge. Functionalizing the nanolaser surface with an antibody, the speciﬁc binding of target antigen is detected with a detection limit 2–4 orders lower than that achieved by current standard methods, enzyme-linked immuno-sorbent assay. Nanolasers also detect negatively-charged deoxyribonucleic acid from their emission intensity. This technique requires neither labels nor spectroscopy, which simpliﬁes screening procedures. Its applicability for high-speed detection of endotoxin and for label-fee imaging of living cells are also demonstrated.

Photonic crystal nanolaser A photonic crystal is a multidimensional periodic structure whose period is similar to its optical wavelength.[1] When the structure comprises high-index-contrast media, it produces a photonic bandgap and acts as a distributed Bragg mirror.[2] Therefore, when a cavity is made of an emitting material such as III–V semiconductors and surrounded by a high-indexcontrast photonic crystal, it will become a laser.[3] A cavity size that is comparable with its emission wavelength is often referred to as a photonic crystal defect, whereas a laser with such a small cavity is referred to as a nanolaser. The fabrication of three-dimensional (3D) structures is very complicated, whereas effective 3D optical conﬁnement is achievable by employing a photonic crystal slab comprising a high-index thin membrane with a 2D hole array. Light is conﬁned by the photonic bandgap and total internal reﬂection inside and outside of the slab plane, respectively. Figure 1 shows the schematic of a nanolaser discussed in this paper.[4,5] As an emitting material, an InP-based semiconductor is often used because the nonradiative surface recombination on processed surfaces is insigniﬁcantly large compared with other semiconductors. A GaInAsP single-quantum well and surrounding GaInAsP barrier and optical conﬁnement layers, all of which are epitaxially grown on InP substrate, represent the membrane with a typical thickness of 180 nm. The standard epitaxial wafer is commercially available as a laser wafer at telecom wavelengths (λ) approximately equal to 1.55 µm. The photonic crystal pattern is deﬁned in a resist by e-beam lithography. The hole diameter and hole pitch are typically 260 and 500 nm, respectively. Here high-throughput drawing is possible because the total area of one nanolaser including all holes is smaller than 20 × 20 µm2. The holes are constructed through the resist via

inductively-coupled plasm

Data Loading...