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Background Recently, histologic grade was removed from salivary tumor nomenclature by the WHO to include disease of higher grade. One such entity, cribriform adenocarcinoma (CAC), is an aggressive group of polymorphous adenocarcinoma (PAC), with frequent nodal metastasis and locoregional recurrence. We aim to examine the biologic behavior of this disease as compared with the PAC general cohort inclusive of all subtypes. Methods A systematic review of the literature on polymorphous adenocarcinoma and cribriform adenocarcinoma was completed. A descriptive analysis was performed for the following predictor variables: nodal and distant metastasis, in addition to recurrence. The outcome variables, disease free recurrence, and disease specific survival, where plotted using Kaplan-Meier curves. Results PAC and CAC both show median age of diagnosis in the sixth decade of life and a female predominance. CAC occurs most frequently in the tongue and PAC in the palate. The 2 groups show a similar biologic behavior in regards to incidence of distant metastasis (4.1 vs 5.5%), recurrence (12.5 vs 17.8%), and death from disease (3 vs 2.7%). However, there was an increased incidence of nodal metastasis in CAC (53%) as compared with that in PAC of all subtypes (14%). Conclusions CAC exhibits more aggressive biologic behavior as compared with the PAC cohort. Although CAC is not an officially recognized entity, these tumors likely comprise a significant portion of the cases of PAC with poor outcomes and are deserving of attention and consideration for escalation in oncologic treatment.

Cowden syndrome is an autosomal dominant disorder characterized by hamartomas, as well as benign and malignant neoplasms that may present in organ systems throughout the body. It also poses an increased lifetime cancer risk in those with the disorder. Its clinical presentation is often variable, and diagnosis can be challenging. In the head and neck region, it can present as thyroid enlargement or mass formation, cutaneous and mucocutaneous lesions of the skin and the oral cavity. The most typical oral manifestations of Cowden syndrome are oral papillomatosis and a cobblestone appearance of the mucosa. We present a case of vascular malformation of the tongue in a patient with Cowden syndrome. This lesion was similar in appearance to a cutaneous hamartoma on the patient's upper extremity. He had received prior surgical intervention for this tongue mass, and complete resection was recommended subsequently. However, in search of a less invasive treatment to minimize impact on speech and oral function, sclerotherapy was performed, resulting in resolution of the lesion. Sclerotherapy is a well-documented treatment for head and neck vascular malformations, but it is not universally employed. In our patient with atypical oral manifestation of Cowden syndrome, bleomycin sclerotherapy was employed, resulting in resolution of the lesion, as well as preservation of speech articulation and oral function.

We demonstrate that the stimulated Brillouin scattering of a 250 mm long distributed feedback Raman fiber laser can self-pulse with repetition rates up to 7 MHz, pulse widths of 25 ns, and peak powers of 1.2 W. While both CW and pulsed lasing are produced from a bespoke grating at 1119 nm this laser design could be constructed at almost any wavelength, as the Raman and Brillouin gain regions are relative to the pump wavelength. The laser has a low lasing threshold for a Raman laser of 0.55 W, a peak slope efficiency of 14 %, and a maximum average output of 0.25 W. An investigation of beating between pure Raman and Raman-pumped Brillouin lasing shows that the outputs of the two processes are highly correlated and thus the Brillouin lasing is essentially single-frequency when CW and near transform limited for pulsed operation. A phenomenological model of the Raman-Brillouin interaction shows that the pulsing behaviour of such a cavity is expected and produces very similar pulsing to that the seen in experimental results.

We report on self-pulsing in distributed-feedback single-frequency Raman fibre lasers. We see a periodic reduction in intra-cavity power associated with each pulse and propose that this self-pulsing arises from parasitic Brilluoin scattering cavity dumping the Raman.

We analyze analytically and numerically the efficiency of UV-written tilted Bragg gratings for optical beam delivery from integrated waveguides towards atom or ion clouds trapped above the chip for quantum technology applications.

We demonstrate an increase in achievable refractive index change of 1.2×10-3 in Gedoped silica in writing waveguides and gratings using pulsed 213 nm light to deposit the same total fluence over multiple writing passes.

We report the development of 45° blazed gratings in integrated waveguides using a holographic UV laser inscription technique for out-of-plane free-space coupling of beams.

We investigate the dynamics of pulsed 213 nm planar Bragg grating writing for a range of powers and fluences. We report the regime for achieving high index contrast, and where damage is likely to occur.

We report on the regular self-pulsing of a 1119 nm Raman DFB laser at the Brillouin Stokes shift of the Raman laser. We also detail four-wave mixing between the pump and Raman.

A method for the UV writing of Bragg gratings in germanium doped photonic crystal fiber is presented. This technique uses small-spot direct UV writing to generate transmission spectra at 1550nm.

Bragg gratings were written into planar doped-silica membranes with a 213nm laser. These were written over large areas using cylindrical lenses, and the resulting gratings and diffraction orders were investigated.

We demonstrate out-of-plane coupling of large (millimeter scale) and small (focusing) beams using holographically fabricated blazed-chirped gratings in doped silica. The 45° blaze angle was achieved via a prism coupling mechanism.

We demonstrate femtosecond laser induced photosensitivity allowing to perform direct UV laser writing in pure fused silica, offering new 3D design freedoms.

A modification to the small-spot direct UV writing scheme is presented to resolve apodization-induced phase shift. Numerical and analytic simulations of the scheme are demonstrated alongside experimental results of gratings fabricated with the modified technique.

We present the first substantive investigation into the photosensitivity response of planar-doped silica to pulsed 213 nm light. We look at the response over a broad range of fluences and average powers to identify suitable regimes for simultaneous waveguide and Bragg grating writing. Unlike previously reported work, we do not observe any clear evidence of a similar non-linear photosensitivity response in B/Ge doped silica. We discuss laser-induced damage, saturation of photosensitivity, and grating response. This paper presents writing regimes for small spot direct UV writing where the photosensitivity and grating response are optimum, thereby confirming the suitability of the fabrication approach for complex devices.

Vibrational modes of chemical bonds in organic erbium (Er

Vibrational modes of chemical bonds in organic erbium (Er3+) materials play an important role in determining the efficiency of the 1.5 μm Er3+ emission. This work studies the energy coupling of the Er3+ intra-4f transitions and vibrational modes. The results demonstrate that the coupling introduces enormous nonradiative internal relaxation, which condenses the excited erbium population on to the 4I13/2 state. This suggests that vibrational modes can be advantageous for optimizing the branching ratio for the 1.5 μm transition in organic erbium materials. Through control of the quenching effect on to the 4I13/2 state and a reliable determination of intrinsic radiative rates, it is found that the pump power for population inversion can be reduced by an order of magnitude at high erbium concentrations compared to conventional inorganic erbium materials.

Experimental data collection methods and a corresponding numerical model are presented to investigate the quality of waveguide fabrication in nonlinear optics. The method utilises white light interferometry and standard image recognition techniques to calculate a waveguide propagation constant function. This enables comparison of a numerical second harmonic spectrum in quasi-phasematched materials, such as periodically poled lithium niobate, with the waveguide’s experimental phase-matching spectrum. Using the presented method, a 3rd order polynomial fit to waveguide ridge width is demonstrated to be in good agreement with experimental phasematching spectra. The presented technique provides a nondestructive route to discriminate between issues in fabrication steps in nonlinear waveguide design.

We theoretically and numerically investigate the performance of tilted Bragg gratings in planar waveguides, fabricated by direct UV writing in photosensitive silica, to couple light out of a chip. An analytic expression is derived for the coupling efficiency and validated numerically by finite element simulations. Using the analytic result, we can design gratings to generate output beams in free space of any specific shape and calculate their overall power coupling efficiency. Our simulations indicate that for currently achievable grating index contrasts devices of millimeter length are most suitable for this technology.

Two methods to inscribe co‐located fibre Bragg gratings using the small spot direct UV writing technique are described and compared, namely: superimposed gratings, which are written one over the other at the same spatial location, and superstructured gratings, where a refractive index modulation is digitally designed and all spectral signatures are written in a single step writing process. In this letter, we report a record number of 45 superimposed and 39 superstructured gratings being inscribed with an interference spot of only 14 μm in diameter.

We investigate designs of out-of-plane planar waveguide gratings that can generate any arbitrarily-shaped light beam in a target location in free space above the sample. Such devices will form an essential component in compact quantum technology devices for optical beam delivery to clouds of neutral atoms or individual ions in surface traps for, e.g., quantum sensing or quantum computing.

Uniform Fiber Bragg Grating sensors based on Polarization-Maintaining fibers are designed for simultaneous longitudinal strain and temperature measurement of Carbon Fiber Reinforced Polymer laminates. Panda, Bow tie and Pseudo-rectangle optical fiber shape sections are investigated employing three different embedding methods, for each optical fiber. The simulation accurately takes into account that the fibers are embedded in unidirectional Carbon Fiber Reinforced Polymer and covered between two adhesive polyimide films. An exhaustive, accurate and robust investigation of the mechanisms originating Bragg wavelength shift is developed by considering a complete multiphysical model including: the propagation modes and their interaction, the birefringence, the optomechanical and thermal behaviour of both the optical fiber and the embedding composite material. For the first time, the use of polyimide films is proposed to obtain an increase of temperature sensor sensitivity, reducing the stress-transfer, due to thermal expansion, between the composite laminate and the sensing element. The designed Fiber Bragg Grating sensors are compared and their potential application, for simultaneous strain and temperature measurement of Carbon Fiber Reinforced Polymer is discussed.

We propose and investigate theoretically the use of bi-directional propagation of light in silica integrated coupled waveguide structures for linear optical processing of fiber-coupled photons. We show that the class of linear operations that can be implemented in such a system is given by symmetric and unitary matrices. We present how an arbitrary $4\times 4$ coupler of this form can be realized by a linear sequence of more fundamental $2\times 2$ couplers and single-waveguide phase shifters and discuss in detail the implementation in a silica integrated platform utilizing direct UV-written waveguides and long- and short-period grating couplers with tilted gratings for optimized coupling efficiency.

With an ever-increasing interest in secure and reliable free-space optical communication, upconversion detectors enabled through nonlinear optical processes are an attractive route to transmitting data as a mid-infrared signal. This spectral region is known to have a higher transmissivity through the atmosphere. In this work, we present an upconversion scheme for detection in the silicon absorption band using magnesium-oxide doped periodically poled lithium niobate to generate 21 mW of a 3.4 µm signal from commercial laser sources using a difference frequency generation process. Following a further nonlinear frequency conversion, via sum-frequency generation, the resulting signal at 809 nm is detected. We achieve >50 µW of signal and bit error rates of 10−7 from a single-pass nonlinear conversion for both the transmitter and receiver systems without the need for additional optical amplifiers at the receiving end. The error rates due to potentially reduced laser powers at the receiver end are investigated and laser noise transfer through our system is discussed.

This work proposes a new route to overcome the limits of the thermal poling technique for the creation of second order nonlinearity in conventional silica optical fibers. We prove that it is possible to enhance the nonlinear behavior of periodically poled fibers merging the effects of poling with the nonlinear intrinsic properties of some materials, such as MoS2, which are deposited inside the cladding holes of a twin-hole silica fiber. The optical waves involved in a second harmonic generation process partially overlap inside the thin film of the nonlinear material and exploit its higher third order susceptibility to produce an enhanced SHG., SCOPUS: ar.j, info:eu-repo/semantics/published

In this paper we present the first example of waveguides fabricated by UV writing in non-hydrogen loaded Ge-doped planar silica with 213 nm light. Single mode waveguides were fabricated and the numerical apertures and mode field diameters were measured for a range of writing fluences. A peak index change of 5.3 x 10 −3 was inferred for the waveguide written with 70 kJ cm −2. The refractive index change is sufficient to match the index structure of standard optical fiber. Uniformity of the written structures was measured and a propagation loss of 0.39 ± 0.03 dB cm −1 was determined through cutback measurements.

We demonstrated two different methods for fabricating a record number of over 40 co-located fiber Bragg gratings: consecutively written superimposed and digitally synthesized superstructure gratings fabricated through small spot direct UV writing. The development of ’AC’ refractive index for superimposed gratings has been analyzed.

We report the first demonstration of integrated waveguides and Bragg gratings direct UV written into planar silica using a fifth harmonic 213 nm laser without hydrogen loading. We observe 0.44 ±0.26 dB cm − 1 propagation loss.

In this paper, a polarization maintaining (PM) Panda fiber embedded in unidirectional Carbon Fiber Reinforced Polymer (CFRP) is investigated for sensing application in the field of aerospace composite materials. The Stress and Thermal distributions due to a uniaxial load applied and a temperature variation are evaluated. In particular, the effects of the resulted strains over propagating modes are analysed through a mode analysis approach, with a 2D-FEM model, by taking into account the residual Stress-Induced Birefringence of the Panda fiber. Then, the shifts of the Bragg wavelength of a uniform Fiber Bragg grating (FBG) are obtained via the Transfer Matrix Method (TMM) and the sensitivities to variation of strain and temperature are accurately calculated.

In this paper, a comprehensive model is developed in order to take into account the effect of stress birefringence, longitudinal strain and temperature change on a sensor based on a Fiber Bragg Grating (FBG) written in a Polarization-Maintaining (PM) Panda Fiber. The electromagnetic and mechanical investigation is performed via the Finite Element Method (FEM) to determine stress-induced birefringence and its effect on the light propagation in single mode polarization maintaining optical fibers. The sensing feature of a FBG, subjected to longitudinal strain and temperature variation, is investigated with reference to the resonant wavelength shift. The reflection spectra, obtained by using transfer matrix method, show high sensitivity optical responses to thermal and mechanical stresses.

We propose and numerically simulate a new and highly compact integrated 4x4 mode coupler based on two single-mode waveguides exploiting both forward and backward propagating directions to double the number of modes. The two parallel waveguides are coupled via long and short-period gratings to the co- and counterpropagating directions, respectively, of a single cladding mode of the device which acts as a bus between the waveguides. By connecting all end facets to optical circulators we construct a device with four input and output ports but only using two single-mode waveguides. Such a device can be fabricated in a single micromachined silica ridge structure. A photosensitive raised index layer is used for vertical confinement that supports multiple modes horizontally. We UV-write the waveguides and the Bragg gratings and provide a tilt angle to improve coupling. We have demonstrated this technology before for a polarizing waveguide-to-waveguide coupler and have simulated other unidirectional devices. We use coupled mode theory to simulate the system. By tailoring the grating parameters, we can achieve a wide variety of coupling ratios. Analytically, we find a set of solutions in which no light escapes via the cladding modes through the ends of the device and we have calculated device parameters to achieve a wide range of splitting ratios including coupling light from one input port equally into all output ports. Moreover, we derived analytically a set of parameters to implement a Walsh-Hadamard transformation and are investigating further options to implement a universal 4x4 mode-coupler on this platform. We envisage that the device can be used for quantum information processing where two qubits are encoded in the waveguides using a photon in each propagation direction.