Association Between Burn Location and Psychological Distress: A Burn Model System National Database Study.

Burn injuries often lead to psychological distress, from depression and anxiety to adjustment concerns and posttraumatic stress. There is some evidence that the anatomical location of burn injuries (eg, head/neck, feet) has a specific negative effect on psychological functioning. The purpose of this study was to examine the associations between burn injury location and emotional distress. First, we administered self-report questionnaires to burn survivors with ≤ 5% TBSA at a single adult outpatient burn clinic. Second, we used a cross-sectional analysis of the Burn Model System National Database. The mean values of each measure of psychological distress (ie, quality of life, self-esteem, depression, posttraumatic stress, anxiety, and, for contrast, posttraumatic growth) were examined for each anatomical location for those participants with a burn in those anatomical areas against those with burn in other areas. Using Kruskal-Wallis tests to compare psychological distress, we found no significant differences in outcome measures in either sample analyzed in our study. These findings contrast with prior literature indicating the negative psychological effect of burn injuries on certain locations in the body. Further research should explore whether larger burns (ie, < 5% TBSA) affecting critical areas of the body may be associated with psychological distress.

Compact thin film lithium niobate folded intensity modulator using a waveguide crossing.

A small footprint, low voltage and wide bandwidth electro-optic modulator is critical for applications ranging from optical communications to analog photonic links, and the integration of thin-film lithium niobate with photonic integrated circuit (PIC) compatible materials remains paramount. Here, a hybrid silicon nitride and lithium niobate folded electro-optic Mach Zehnder modulator (MZM) which incorporates a waveguide crossing and 3 dB multimode interference (MMI) couplers for splitting and combining light is reported. This modulator has an effective interaction region length of 10 mm and shows a DC half wave voltage of roughly 4.0 V, or a modulation efficiency (Vπ ·L) of roughly 4 V·cm. Furthermore, the device demonstrates a power extinction ratio of roughly 23 dB and shows .08 dB/GHz optical sideband power roll-off with index matching fluid up to 110 GHz, with a 3-dB bandwidth of 37.5 GHz.

Subvolt electro-optical modulator on thin-film lithium niobate and silicon nitride hybrid platform.

A low voltage operation electro-optic modulator is critical for applications ranging from optical communications to an analog photonic link. This paper reports a hybrid silicon nitride and lithium niobate electro-optic Mach-Zehnder modulator that employs 3 dB multimode interference couplers for splitting and combining light. The presented amplitude modulator with an interaction region length of 2.4 cm demonstrates a DC half-wave voltage of only 0.875 V, which corresponds to a modulation efficiency per unit length of 2.11 V cm. The power extinction ratio of the fabricated device is approximately 30 dB, and the on-chip optical loss is about 5.4 dB.

High-performance racetrack resonator in silicon nitride - thin film lithium niobate hybrid platform.

In this paper, we propose an electro-optic modulator design in a hybrid Si3N4-X-cut LiNbO3. The modulator is based on a modified racetrack resonator and performs at both DC and heightened frequencies. Here the driving electrodes are defined along the straight section of the racetrack. This is done to maximize modulation and minimize modulation-cancelation that occurs in a conventional X-cut LiNbO3-based resonator due to the directional change of the electric field in the micro-ring. The single bus racetrack resonator is formed in a hybrid Si3N4-LiNbO3 platform, to guide the optical mode. The fabricated device is characterized and has a measured tunability and intrinsic quality factor (Q) of 2.9 pm/V and 1.3 × 105, respectively. In addition, the proposed racetrack device exhibits enhanced electro-optic conversion efficiency at modulation frequencies that match with the racetrack's optical free spectral range (FSR). For example, at the modulation frequency of 25 GHz, which corresponds to the fabricated device's optical FSR frequency, a ∼10 dB increase in electro-optic conversion efficiency is demonstrated. With the enhancement, our measured device demonstrates a conversion efficiency comparable to non-resonant thin-film LiNbO3 devices that possess RF electrodes that are 10 times longer in length.

Vertical mode transition in hybrid lithium niobate and silicon nitride-based photonic integrated circuit structures.

This Letter presents an optical mode transition structure for use in Si3N4/LiNbO3-based hybrid photonics. A gradual modal transition from a Si3N4 waveguide to a hybrid Si3N4/LiNbO3 waveguide is achieved by etching a terrace structure into the sub-micrometer thick LiNbO3 film. The etched film is then bonded to predefined low pressure chemical vapor deposition Si3N4 waveguides. Herein we analyze hybrid optical devices both with and without the aforementioned mode transition terrace structure. Experimental and simulated results indicate that inclusion of the terrace significantly improves mode transition compared to an abrupt transition, i.e., a 1.78 dB lower mode transition loss compared to the abrupt transition. The proposed transition structure is also applied to the design of hybrid Si3N4-LiNbO3 micro-ring resonators. A high-quality factor (Q) resonator is demonstrated with the terrace transition which mitigates undesired resonances.

Thin film lithium niobate electro-optic modulator with terahertz operating bandwidth.

We present a thin film crystal ion sliced (CIS) LiNbO3 phase modulator that demonstrates an unprecedented measured electro-optic (EO) response up to 500 GHz. Shallow rib waveguides are utilized for guiding a single transverse electric (TE) optical mode, and Au coplanar waveguides (CPWs) support the modulating radio frequency (RF) mode. Precise index matching between the co-propagating RF and optical modes is responsible for the device's broadband response, which is estimated to extend even beyond 500 GHz. Matching the velocities of these co-propagating RF and optical modes is realized by cladding the modulator's interaction region in a thin UV15 polymer layer, which increases the RF modal index. The fabricated modulator possesses a tightly confined optical mode, which lends itself to a strong interaction between the modulating RF field and the guided optical carrier; resulting in a measured DC half-wave voltage of 3.8 V·cm-1. The design, fabrication, and characterization of our broadband modulator is presented in this work.

110 GHz CMOS compatible thin film LiNbO3 modulator on silicon.

In this paper we address a significant limitation of silicon as an optical material, namely, the upper bound of its potential modulation frequency. This arises due to finite carrier mobility, which fundamentally limits the frequency response of all-silicon modulators to about 60 GHz. To overcome this limitation, another material must be integrated with silicon to provide increased operational bandwidths. Accordingly, this paper proposes and demonstrates the integration of a thin LiNbO3 device layer with silicon and a novel tuning process that matches the propagation velocities between the propagating radio-frequency (RF) and optical waves. The resulting lithium niobate on silicon (LiNOS) modulator is demonstrated to operate from DC to 110 GHz.

Thin LiNbO3 on insulator electro-optic modulator.

This Letter presents a method for the fabrication and integration of a thin LiNbO3 substrate with a Si handle wafer. An inverted ridge structure guides a single optical mode in an electro-optic modulator fabricated on a mechanically thinned substrate. To define an optical waveguide, a ridge structure is first patterned on a 500 µm thick X-cut LiNbO3 wafer; then a low dielectric constant adhesive layer is used to bond the etched LiNbO3 to Si. The LiNbO3 is mechanically thinned to 4 µm, and planar electrodes are patterned. Experimental results demonstrating modulation with a V(π)L of 7.1 V-cm were shown, optical loss was low enough, and film quality high enough, to enable an interaction length of 0.8 cm.