Enhancing and inhibiting stimulated Brillouin scattering in photonic integrated circuits

On-chip nonlinear optics is a thriving research field, which creates transformative opportunities for manipulating classical or quantum signals in small-footprint integrated devices. Since the length scales are short, nonlinear interactions need to be enhanced by exploiting materials with large nonlinearity in combination with high-Q resonators or slow-light structures. This, however, often results in simultaneous enhancement of competing nonlinear processes, which limit the efficiency and can cause signal distortion. Here, we exploit the frequency dependence of the optical density-of-states near the edge of a photonic bandgap to selectively enhance or inhibit nonlinear interactions on a chip. We demonstrate this concept for one of the strongest nonlinear effects, stimulated Brillouin scattering using a narrow-band one-dimensional photonic bandgap structure: a Bragg grating. The stimulated Brillouin scattering enhancement enables the generation of a 15-line Brillouin frequency comb. In the inhibition case, we achieve stimulated Brillouin scattering free operation at a power level twice the threshold

Temporal characterization of a multi-wavelength Brillouin–erbium fiber laser

This paper provides the first detailed temporal characterization of a multi-wavelength-Brillouin-erbium fiber laser (MWBEFL) by measuring the optical intensity of the individual frequency channels with high temporal resolution. It is found that the power in each channel is highly unstable due to the excitation of several cavity modes for typical conditions of operation. Also provided is the real-time measurements of the MWBEFL output power for two configurations that were previously reported to emit phase-locked picosecond pulse trains, concluded from their autocorrelation measurements. Real-time measurements reveal a high degree of instability without the formation of a stable pulse train. Finally, we model the MWBEFL using coupled wave equations describing the evolution of the Brillouin pump, Stokes and acoustic waves in the presence of stimulated Brillouin scattering, and the optical Kerr effect. A good qualitative consistency between the simulation and experimental results is evident, in which the interference signal at the output shows strong instability as well as the chaotic behavior due to the dynamics of participating pump and Stokes waves

Background-free fibre optic Brillouin probe for remote mapping of micromechanics

Brillouin spectroscopy is a century-old technique that has recently received renewed interest, as modern instrumentation has transformed it into a powerful contactless and label-free probe of micromechanical properties for biomedical applications. In particular, to fully harness the non-contact and non-destructive nature of Brillouin imaging, there is strong motivation to develop a fibre-integrated device and extend the technology into the domain of in vivo and in situ operation, such as for medical diagnostics. This work presents the first demonstration of a fibre optic Brillouin probe that is capable of mapping the mechanical properties of a tissue-mimicking phantom. This is achieved through combination of miniaturised optical design, advanced hollow-core fibre fabrication and high-resolution 3D printing. The protype probe is compact, background-free and possesses the highest collection efficiency to date, thus provides the foundation of a fibre-based Brillouin device for remote in situ measurements in challenging and otherwise difficult-to-reach environments, for biomedical, material science and industrial applications

Multi-wavelength gratings formed via cascaded stimulated Brillouin scattering

We present the experimental observation of multi-wavelength fiber Bragg gratings in As2Se3 fiber. The gratings are internally written via two-photon absorption of 1550 nm pump light and its first and second order Stokes waves generated by cascaded stimulated Brillouin scattering (SBS). We demonstrate a parameter regime that allows for 4 dB grating enhancement by suppression of SBS

Widely tunable, low phase noise microwave source based on a photonic chip

Spectrally pure microwave sources are highly desired for several applications, ranging from wireless communication to next generation radar technology and metrology. Additionally, to generate very pure signals at even higher frequencies, these advanced microwave sources have to be compact, low in weight, and low energy consumption to comply with in-field applications. A hybrid optical and electronic cavity, known as an optoelectronic oscillator (OEO), has the potential to leverage the high bandwidth of optics to generate ultrapure high-frequency microwave signals. Here we present a widely tunable, low phase noise microwave source based on a photonic chip. Using on-chip stimulated Brillouin scattering as a narrowband active filter allows single-mode OEO operation and ultrawide frequency tunability with no signal degeneration. Furthermore, we show very low close-to-carrier phase noise. This Letter paves the way to a compact, fully integrated pure microwave source

Advances in chip-based Brillouin sources

We present single- and multifrequency Brillouin lasers based on chalcogenide photonic chip. The high Brillouin gain of chalcogenide and the small waveguide cross-section make it possible to achieve lasing in a few centimeter long waveguide

Dynamics of photoinduced refractive index changes in As2S3 fibers

We investigate the dynamics of photoinduced index changes in chalcogenide As2S3 fibers. Using a novel phase sensitive technique for measuring the photoinduced index change, we find that the index evolution is a two-stage process: it consists of a fast reduction and a subsequent slow increase in the refractive index. We show that the index change depends strongly on the beam intensity with both positive and negative changes possible. These findings can have application in design and fabrication of photoinduced devices such as Bragg gratings and photonic cavities

Efficient inscription of Bragg gratings in As2S3 fibers using near bandgap light

Efficient inscription of Bragg gratings in As2S3 fibers using near bandgap light L. E. Zou,1,2,* I. V. Kabakova,2E. C. Mägi,2E. Li,2C. Florea,3I. D. Aggarwal,3 B. Shaw,4J. S. Sanghera,4and B. J. Eggleton2 1Department of Physics, Nanchang University, Nanchang 330031, China 2Center for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Institute of Photonics and Optical Sciences (IPOS), School of Physics, University of Sydney, NSW, 2006, Australia 3Sotera Defense Solutions, Annapolis Junction, Maryland 20701, USA 4U.S. Naval Research Laboratory, Washington DC 20375, USA *Corresponding author: [email protected] Received May 31, 2013; revised July 7, 2013; accepted July 17, 2013; posted July 18, 2013 (Doc. ID 191549); published September 24, 2013 Efficient inscription of Fiber Bragg gratings (FBGs) in single-mode, thin cladding As2S3fibers is demonstrated by using near bandgap light at 532 nm. The FBGs with the reflectivity of over 80% can be induced in only 80-90 s, substantially faster than in previous reports. The dynamics of the grating growth are investigated in the photosen- sitivity process, showing a fast blue shift of the Bragg wavelength and then a somewhat slower red shift. The aging of the grating after fabrication is also reported, indicating a 37% decay of the grating strength