A Directly-Written Monolithic Waveguide-Laser Incorporating a DFB Waveguide-Bragg Grating

We report the fabrication and performance of the first C-band directly-written monolithic waveguide-laser. The waveguide-laser device was created in an Erbium and Ytterbium doped phosphate glass host and consisted of an optical waveguide that included a distributed feedback Bragg grating structure. The femtosecond laser direct-write technique was used to create both the waveguide and the waveguide-Bragg grating simultaneously and in a single processing step. The waveguide-laser was optically pumped at approximately 980 nm and lased at 1537nm with a bandwidth of less than 4 pm.Comment: 6 pages, 13 references, 4 figure

Investigation of ultrafast laser photonic material interactions: challenges for directly written glass photonics

Currently, direct-write waveguide fabrication is probably the most widely studied application of femtosecond laser micromachining in transparent dielectrics. Devices such as buried waveguides, power splitters, couplers, gratings and optical amplifiers have all been demonstrated. Waveguide properties depend critically on the sample material properties and writing laser characteristics. In this paper we discuss the challenges facing researchers using the femtosecond laser direct-write technique with specific emphasis being placed on the suitability of fused silica and phosphate glass as device hosts for different applications.Comment: 11 pages, 87 references, 11 figures. Article in revie

A 100 mW monolithic Yb waveguide laser fabricated using the femtosecond laser direct-write technique

A femtosecond laser-written monolithic waveguide laser (WGL) oscillator based on a distributed feedback (DFB) architecture and fabricated in ytterbium doped phosphate glass is reported. The device lased at 1033 nm with an output power of 102 mW and a bandwidth less than 2 pm when bidirectionally pumped at 976 nm. The WGL device was stable and operated for 50 hours without degradation. This demonstration of a high performance WGL opens the possibility for creating a variety of narrow-linewidth laser designs in bulk glasses.Comment: 5 pages, 3 figures, submitted journal manuscrip

Co-propagation of maser emission at 1720 and 4765 MHz

MERLIN observations are presented of OH 4765-MHz and OH 1720-MHz masers in the massive star-forming region W3(OH). Two of the three intense spots of maser emission at 4765 MHz are spatially coincident with two similar spots at 1720 MHz in both left-hand circular (LHC) and right-hand circular (RHC) polarizations, to an accuracy of 15 mas. The spots also overlap in velocity when allowance is made for Zeeman splitting of the 1720-MHz line. We conclude that we have found two examples of masers in different rotational levels of OH which are co-propagating through the same column of gas and experiencing competitive gain effects. The third 4765-MHz maser spot was found to have no overlapping counterpart amongst the 1720-MHz masers

Ultrafast laser inscription: perspectives on future integrated applications

This paper reviews the recent advancements achieved using ultrafast laser inscription (ULI) that highlight the cross-disciplinary potential of the technology. An overview of waveguide fabrication is provided and the three distinct types of waveguide cross-section architectures that have so far been fabricated in transparent dielectric materials are discussed. The paper focuses on two key emergent technologies driven by ULI processes. First, the recently developed photonic devices, such as compact mode-locked waveguide sources and novel mid-infrared waveguide lasers are discussed. Secondly, the phenomenon and applications of selective etching in developing ultrafast laser inscribed structures for compact lab-on-chip devices are elaborated. The review further discusses the conceivable future of ULI in impacting the aforementioned fields.</p

Simultaneous Measurement of Strain and Temperature Using a Single Emission Line

In this study, we present and demonstrate a novel sensor system for simultaneous measurement of strain and temperature through a unique combination of a long period grating and a fiber laser based on a fiber Bragg grating. In order to achieve this, a new erbium-doped fiber laser structure is created, showing an optical signal-to-noise ratio of 55 dB and a peak power measured on the optical spectrum analyzer between -5 and 0 dBm. The strain and the temperature information can be obtained by using a unique emission line through monitoring both the fiber laser wavelength shift and the change of the power level, both of which showing a clear linear behavior

New Constraints from PAMELA anti-proton data on Annihilating and Decaying Dark Matter

Recently the PAMELA experiment has released its updated anti-proton flux and anti-proton to proton flux ratio data up to energies of ~200GeV. With no clear excess of cosmic ray anti-protons at high energies, one can extend constraints on the production of anti-protons from dark matter. In this letter, we consider both the cases of dark matter annihilating and decaying into standard model particles that produce significant numbers of anti-protons. We provide two sets of constraints on the annihilation cross-sections/decay lifetimes. In the one set of constraints we ignore any source of anti-protons other than dark matter, which give the highest allowed cross-sections/inverse lifetimes. In the other set we include also anti-protons produced in collisions of cosmic rays with interstellar medium nuclei, getting tighter but more realistic constraints on the annihilation cross-sections/decay lifetimes.Comment: 7 pages, 3 figures, 3 table

Two-photon quantum walks in an elliptical direct-write waveguide array

Integrated optics provides an ideal test bed for the emulation of quantum systems via continuous-time quantum walks. Here we study the evolution of two-photon states in an elliptic array of waveguides. We characterise the photonic chip via coherent-light tomography and use the results to predict distinct differences between temporally indistinguishable and distinguishable two-photon inputs which we then compare with experimental observations. Our work highlights the feasibility for emulation of coherent quantum phenomena in three-dimensional waveguide structures.Comment: 8 pages, 7 figure