Thermally stable fiber Bragg gratings for the mid-IR are demonstrated. While the grating strength and design wavelength typically change during post-annealing, we report here on grating structures which are resilient to temperatures of up to 200°C

Low-loss photonic waveguides in lithium niobate offer versatile functionality as nonlinear frequency converters, switches, and modulators for integrated optics. Combining the flexibility of laser processing with liquid phase epitaxy we have fabricated and characterized lithium niobate channel waveguides on lithium niobate and lithium tantalate. We used liquid phase epitaxy with K2O flux on laser-machined lithium niobate and lithium tantalate substrates. The laser-driven rapid-prototyping technique can be programmed to give machined features of various sizes, and liquid phase epitaxy produces high quality single-crystal, lithium niobate channels. The surface roughness of the lithium niobate channels on a lithium tantalate substrate was measured to be 90 nm. The lithium niobate channel waveguides exhibit propagation losses of 0.26 ± 0.04 dB/mm at a wavelength of 633 nm. Second harmonic generation at 980 nm was demonstrated using the channel waveguides, indicating that these waveguides retain their nonlinear optical properties.

We report on an investigation using ultrafast laser inscription in borosilicate glasses to create in-volume phase optics. An application of an optic fashioned in this way is discussed in the context of broadband “scalar vortex coronagraphy” for astronomical imaging.

Application of 266-nm picosecond (ps) laser ablation and copper (Cu)-plated metallization to p-type selective emitter (SE) passivated emitter and rear cells (PERC) is reported in this paper. Use of a 266-nm ps laser resulted in similar laser-induced periodic surface structures as observed for 355-nm ps laser ablation of a silicon (Si) nitride antireflection coating (ARC) on random-textured Si solar cell surfaces. In addition, it is shown that 266-nm ps laser ablation results in the formation of amorphous Si with an underlying distorted crystalline Si layer at the laser-ablated surfaces. The successful alignment of laser-ablated openings to the heavily doped SE regions resulted in a comparable cell efficiency of Cu-plated SE PERC cells to screen-printed controls, with a maximum cell efficiency of 20.6% being achieved for the Cu-plated cells. The plated cell performance was limited by the recombination losses, and in particular nonideal recombination caused by the use of a shallow emitter, which had been optimized for screen-printed metallization. Engineering of an SE with a junction depth of 0.52 mu m in the heavily doped regions resulted in a 0.3% absolute increase in pseudo fill factor and demonstrated the importance of displacing the p-n junction from the laser-ablated Si surface. Although 355-nm ps laser ablation has been demonstrated to result in strong busbar adhesion in previous reports of Cu-plated cells, significant variability in the busbar adhesion of the fully plated SE PERC cells resulted by 266-nm ps laser ablation. The predicted increased sensitivity of 266-nm laser ablation to the ARC thickness and the possibility that surface oxides were not uniformly removed across wafers before plating may have affected the uniformity of silicide formation and hence the adhesion of the plated busbars.

We report on single longitudinal mode Yb:YAG waveguide lasers with 2 W of output power and high efficiency. The distributed feedback (DFB) lasers are based on ultrafast laser inscribed waveguide Bragg gratings.

Traditionally, fabrication processes to produce microelectrode arrays for neural stimulating electrodes have employed photolithography and a photoresist layer to produce a pattern on a substrate which subsequently has a metal layer deposited. The deposited metal layer is then used to create stimulating electrodes that will ultimately be in close contact with neural tissue. While the process enables accurate fabrication at a reasonable cost, the use of photoresist in the process presents a number of issues. Photoresist is a contamination risk with the potential for chemicals to be absorbed into the silicone, which will then subsequently be in close proximity to neural structures, introducing a risk of toxicity. In addition, due to the use of flexible substrates such as silicone elastomer, patterning of films greater than 1μm thick can be difficult.Whilst an obvious solution would be to avoid using photoresist in the fabrication process, few alternatives have been systematically investigated. We investigated use of shadow masks fabricated from glass, brass and silicone elastomer, and exploitation of the natural tackiness of the silicone substrate for mask adhesion. All three mask materials attached well to silicone, but each presented differing degrees of difficulty during alignment and mask removal.Subsequently, thin gold films (∼20nm) and thick platinum films (∼8μm) were deposited on the silicone substrates using the shadow masks. We discuss the mask fabrication, pattern definition, the difficulties which arose, and the benefits of using shadow masks for the fabrication of medical devices.

We report a study of ultrafast laser waveguide inscription in two magneto-optical glasses. Two types of femtosecond laser systems operating in kHz and MHz repetition rate regimes are used for waveguide fabrication. Single mode waveguides in the visible are obtained in both writing regimes and exhibit distinct optical properties depending on laser writing conditions and the nature of glasses. Photodarkening, produced as a fabrication byproduct and associated with waveguide propagation loss, is shown to be reversible via annealing. Photodarkening behaves differently in the magneto-optical glasses studied, most likely due to large differences in the concentration of lanthanum and/or gallium in the materials. (C) 2013 Optical Society of America

We report femtosecond laser direct writing of single mode waveguides in a range of magneto-optical glasses. Significant photodarkening, produced as a fabrication byproduct and associated with propagation loss, is shown to be reversible via annealing.

In our community outreach activities, we have been developing teaching tools to inform high school students about Optics and Photonics. While there is research supporting the idea that incorporating computer games into education can create a 'strong cognitive effect', others suggest that games should merely be used as a teaching tool, rather than as a primary vehicle for teaching. Thus we chose to develop an open-ended Photonics Simulator using Flash, employing photonic components as building blocks to form a communications system, within a classroom lesson including an illustrated talk with a simple optical fibre demonstration. The virtual photonics components have the same properties as the devices used in actual telecommunications links and in our research laboratories. The software is available to download. We trialled the Photonics Simulator during a single lesson (lessons ranged from 50 minutes to 90 minutes) with five Year 9 or Year 10 classes (from three schools - coeducational, girls only and boys only) during 2007. We gave them a short survey before the lesson to establish their level of knowledge of photonics, and then administered a slightly longer survey, including some repeated questions, after the lesson. The level of knowledge of photonics was significantly improved in every class and in every subgroup tested. (For example answers on 'the function of an optical amplifier' improved from 40% correct/partly correct to 70% correct/partly correct). Furthermore, the 'hands-on' nature of the simulator was effective in engaging the students, (94% 'enjoyed playing the game') and showing them the basis of the communications systems that underpin the Internet. We created a simulator based on Flash which can be used on both PC and Macintosh computing platforms. It incorporates a glossary of terms to introduce the main components and concepts used in the simulator, as well as offering short movies and animations to demonstrate concepts more vividly. It is intended to become part of the teacher's toolkit for introducing science students to photonics. We incorporated the simulator into our presentations to secondary students. We deliberately did not direct students as to how to set it up, as we wanted to give the students an open choice as to how to interact with the simulator. Indeed, we found that most students preferred to 'hack' rather than be issued with instructions, and many would open the simulator when they were supposed to be busy on another aspect of the presentation. We also included other activities such as an animation of a photonic chip or a freeze-frame movie showing how various photonic components work, and a 'real' demonstration of a laser with optical fibre.

In our community outreach activities, we have been developing teaching tools to inform high school students about Optics and Photonics. While there is research supporting the idea that incorporating computer games into education can create a ‘strong cognitive effect’, others suggest that games should merely be used as a teaching tool, rather than as a primary vehicle for teaching. Thus we chose to develop an open-ended Photonics Simulator using Flash, employing photonic components as building blocks to form a communications system, within a classroom lesson including an illustrated talk with a simple optical fibre demonstration. The virtual photonics components have the same properties as the devices used in actual telecommunications links and in our research laboratories. The software is available to download. We trialled the Photonics Simulator during a single lesson (lessons ranged from 50 minutes to 90 minutes) with five Year 9 or Year 10 classes (from three schools - coeducational, girls only and boys only) during 2007. We gave them a short survey before the lesson to establish their level of knowledge of photonics, and then administered a slightly longer survey, including some repeated questions, after the lesson. The level of knowledge of photonics was significantly improved in every class and in every subgroup tested. (For example answers on ‘the function of an optical amplifier’ improved from 40% correct/partly correct to 70% correct/partly correct). Furthermore, the ‘hands-on’ nature of the simulator was effective in engaging the students, (94% ‘enjoyed playing the game’) and showing them the basis of the communications systems that underpin the Internet.

We report measurements of parameters important to Raman laser design for single crystal synthetic diamond. Raman laser operating space is assessed as functions of the pump wavelength, temporal format and design architecture.

For the first time we explore femtosecond laser writing of waveguides in magneto-optical glasses using athermal writing inscription. Single mode guidance at visible is demonstrated and opportunities for optional isolators will be reported.

We report graphite-free laser etching of diamond surfaces using 266 nm laser pulses for a wide range of incident fluences below the threshold for ablation. The etching rate is proportional to the (fluence)(x) where x = 1.88 +/- 0.16 over the range 10(-6) - 10(-2) nm per pulse for incident pulse fluences 1 - 60 J/cm(2). Surface sensitive near edge x-ray fine absorption structure measurements (partial electron yield NEXAFS) reveal that etching does not significantly alter the surface structure from the initial oxygen terminated and graphite-free state. The etching process, which is consistent with a mechanism involving the desorption of carbon species via the decay of 2-photon excited excitons near the surface, appears to have no threshold and is promising for creating a range of high resolution structures. (C) 2011 Optical Society of America

A novel, dual-band, planar artificial magnetic conductor (AMC) structure is presented. For the same operating frequencies, the unit cell length is approximately one third of that of a previous dual-band AMC, which also did not require vias. This novel AMC surface also offers additional flexibility in controlling the operating frequencies and bandwidths.

High quality lithium niobate planar waveguides, with LiTaO3 substrates, were grown using liquid phase epitaxy from K2O flux. The waveguides do not exhibit impurity absorption in the visible, yielding efficient second harmonic generation.

In the “real world”, Photonics is somewhat invisible to those who rely upon it worldwide. We would like students to connect their everyday experiences of communications with the underlying ideas in Photonics. To do this, we have developed the Photonics Simulator to illustrate to high school students how text or information is coded into binary optical signals which are relayed through photonic communications networks from sender to receiver. Using our simulator, students construct a virtual network, and then test it by sending messages. The messages are coded using ASCII binary code as digital signals in data packets with address headers, which need to be switched, combined, amplified, or delayed to get to their designated address. The students must manage their power budget, correctly target each message address, and avoid collisions of data packets to send their messages uncorrupted and error-free. We tested an early version of the simulator with five Year 9 and 10 classes. The students provided many constructive comments and their feedback was used to improve the graphical interface of the simulator. We subsequently tested the simulator with 80 Year 9 students in short workshops. Overall we had a very positive response - it was more fun than a normal class, and interactivity helped students retain information. Students enjoy the visual aspects– they see how messages are delivered, and learn the function of each network component by experiment. Tests of the simulator at the Macquarie Siemens Science Experience were also encouraging, with one student even sneaking back to class to complete his challenges!

Dielectric rod antennas have advantages as elements of focal plane arrays for imaging applications at terahertz frequencies. As well as good directivity and moderate bandwidth they are readily integrated with diode detectors. To demonstrate these attributes we describe the fabrication of a prototype antenna by laser ablation. Theoretical and measured results are presented for a dielectric rod antenna operating at 600 GHz.

By identifying appropriate quasi-phase-matching (QPM) conditions in z-cut congruent lithium niobate, we demonstrate simultaneous QPM of type-I (ooe) and higher order type-0 (eee) second-harmonic-generation, which share a common second harmonic wave. We demonstrate this experimentally at 1064nm, and show that cascading between these processes occurs. The cascading can result in energy exchange between the cross-polarized fundamentals, indicative of an equivalent 3rd order process. The nonlinear phase shifts and transfer functions resulting from this cascading are explored numerically.