Coupled-wave theory of multiple-stripe semiconductor injection lasers

We apply coupled-wave theory to describe the lateral modes of semiconductor lasers with a periodic gain and refractive-index variation across their widths. The model is relevant to devices whose complex index of refraction is determined by current injection from closely spaced parallel electrodes. Good agreement is observed between the analytical modes and those computed numerically for comparison

Saturable nonlinear dielectric waveguide with applications to broad-area semiconductor lasers

Self-focusing in a passive dielectric waveguide with a saturable nonlinearity is studied. The eigensolutions constitute a good approximation to the lateral modes of broad-area semiconductor lasers under low-duty-cycle pulsed conditions. The laser modes are predicted to consist of adjacent filaments coupled in phase, leading to a single-lobed far field, and to be stable with increased current injection above saturation intensity. The ultimate filament spacing is inversely proportional to the threshold gain, and thus wider filaments are expected in low-threshold broad-area lasers

Broadband Tuning (170nm) of InGaAs Quantum Well Lasers

The wavelength tuning properties of strained InGaAs quantum well lasers using an external grating for feedback is reported. Tunable laser oscillation has been observed over a range of 170 nm, between 840 and 1010 nm, under pulsed current excitation. The optimal conditions for broadband tunability for the InGaAs lasers are different from GaAs lasers, which is attributed to a difference in spectral gain curves. Together with an optimised GaAs quantum well laser the entire region between 740 and 1010 nm is spanned

Self-stabilized Nonlinear Lateral Modes of Broad Area Lasers

The lateral modes of broad area lasers are investigated theoretically. The nonlinear interaction between optical field and effective refractive index leads to a saturable nonlinearity in the governing field equation, so that self-modulated solutions are found to be stable with increased current injection above saturation intensity. We derive approximate analytical solutions for traveling wave fields within the broad area laser. The field amplitude consists of a small ripple superimposed on a large dc value. Matching fields at the boundary determines the modulation depth and imparts an overall phase curvature to the traveling wave mode. There are multiple lateral modes for a given set of operating conditions, and modes with successively more lobes in the ripple have greater overall phase curvature. In contrast to the linear problem, several lateral modes can achieve the same modal gain, for a given injected current density, by saturating the gain to different extent. Thus, these modes would exhibit slightly different optical powers

Broadband tunability of gain-flattened quantum well semiconductor lasers with an external grating

Quantum well lasers are shown to exhibit flattened broadband gain spectra at a particular pumping condition. The gain requirement for a grating-tuned external cavity configuration is examined and applied to a semiconductor quantum well laser with an optimized length of gain region. The predicted very broadband tunability of quantum well lasers is confirmed experimentally by grating-tuning of uncoated lasers over 85 nm, with single longitudinal mode output power exceeding 200 mW

Optimised Fabry-Perot (AlGa)As quantum well lasers tunable over 105 nm

Uncoated, Fabry-Perot (AlGa)As semiconductor lasers are tuned over 105nm in a grating-coupled external cavity. Broadband tunability is achieved by optimising the resonator loss so as to invoke lasing from both the first and second quantised states of the single quantum well active region

Medication adherence among Turkish type-2 diabetics in Belgium: results from a qualitative study

Abstract title: Medication adherence among Turkish type-2 diabetics in Belgium: results from a qualitative study. Aim: Prevalence of diabetes in Belgium is 2 to 3 times higher among people from Turkish descent. Medication adherence, an essential element of the diabetic regimen, appears to be lower among nonwhite ethnic groups. This study identifies factors influencing medication adherence among Turkish type-2 diabetics living in Belgium. Methods: Since this topic hasn’t been studied before we conducted an explorative, qualitative study using semi-structured in-depth interviews with the aid of an interpreter. The topicslist was based on insights from the literature and conversations with Turkish diabetics and health care workers and was slightly adjusted after the first interviews. 21 Turkish type-2 diabetics living in Belgium were selected using theoretical sampling. Respondent’s most recent HbA1c-values were also collected. Interviews lasted between 2 and 5 hours, were audio-taped, fully transcribed and translated. Thematic analysis was conducted by the first two authors with different educational backgrounds (sociologist/pharmacist). The first phase was a detailed, thematic analysis of the individual cases, in the second phase an analysis across cases, distinguishing adherers from non-adherers, identified factors influencing medication adherence. NVivo 8 was used for managing, coding and analysing the qualitative data. Results: Factors influencing medication adherence among type-2 diabetics from Turkish descent include knowledge of and attitudes towards diabetes and antidiabetics, health and medication beliefs, social support from health care providers and family members, the nature of the patient-provider relationship, perceptions of health care worker’s expertise and social roles in daily life. A typology was constructed identifying different constellations of factors that distinguish adherers from non-adherers. Implications for clinical practice are discussed. Conclusion: This qualitative study identifies factors influencing medication adherence among type-2 Turkish diabetics living in Belgium and provides a typology, distinguishing adherers from non-adherers, that may guide clinical practice. Results from this qualitative study will be tested in a future, quantitative study

Medication adherence among Turkish type-2 diabetics in Belgium: results from a qualitative study

Abstract title: Medication adherence among Turkish type-2 diabetics in Belgium: results from a qualitative study. Aim: Prevalence of diabetes in Belgium is 2 to 3 times higher among people from Turkish descent. Medication adherence, an essential element of the diabetic regimen, appears to be lower among nonwhite ethnic groups. This study identifies factors influencing medication adherence among Turkish type-2 diabetics living in Belgium. Methods: Since this topic hasn’t been studied before we conducted an explorative, qualitative study using semi-structured in-depth interviews with the aid of an interpreter. The topicslist was based on insights from the literature and conversations with Turkish diabetics and health care workers and was slightly adjusted after the first interviews. 21 Turkish type-2 diabetics living in Belgium were selected using theoretical sampling. Respondent’s most recent HbA1c-values were also collected. Interviews lasted between 2 and 5 hours, were audio-taped, fully transcribed and translated. Thematic analysis was conducted by the first two authors with different educational backgrounds (sociologist/pharmacist). The first phase was a detailed, thematic analysis of the individual cases, in the second phase an analysis across cases, distinguishing adherers from non-adherers, identified factors influencing medication adherence. NVivo 8 was used for managing, coding and analysing the qualitative data. Results: Factors influencing medication adherence among type-2 diabetics from Turkish descent include knowledge of and attitudes towards diabetes and antidiabetics, health and medication beliefs, social support from health care providers and family members, the nature of the patient-provider relationship, perceptions of health care worker’s expertise and social roles in daily life. A typology was constructed identifying different constellations of factors that distinguish adherers from non-adherers. Implications for clinical practice are discussed. Conclusion: This qualitative study identifies factors influencing medication adherence among type-2 Turkish diabetics living in Belgium and provides a typology, distinguishing adherers from non-adherers, that may guide clinical practice. Results from this qualitative study will be tested in a future, quantitative study

Older patients' prescriptions screening in the community pharmacy: development of the Ghent Older People's Prescriptions community Pharmacy Screening (GheOP3S) tool

Background: Ageing of the population often leads to polypharmacy. Consequently, potentially inappropriate prescribing (PIP) becomes more frequent. Systematic screening for PIP in older patients in primary care could yield a large improvement in health outcomes, possibly an important task for community pharmacists. In this article, we develop an explicit screening tool to detect relevant PIP that can be used in the typical community pharmacy practice, adapted to the European market. Methods: Eleven panellists participated in a two-round RAND/UCLA (Research and Development/University of California, Los Angeles) process, including a round zero meeting, a literature review, a first written evaluation round, a second face-to-face evaluation round and, finally, a selection of those items that are applicable in the contemporary community pharmacy. Results: Eighteen published lists of PIP for older patients were retrieved from the literature, mentioning 398 different items. After the two-round RAND/UCLA process, 99 clinically relevant items were considered suitable to screen for in a community pharmacy practice. A panel of seven community pharmacists selected 83 items, feasible in the contemporary community pharmacy practice, defining the final GheOP3S tool. Conclusion: A novel explicit screening tool (GheOP3S) was developed to be used for PIP screening in the typical community pharmacy practice