Numerical modeling of lathanide-ion doped fibre lasers operating within mid-infrared wavelength region

We discuss the numerical modelling of lanthanide-ion doped chalcogenide glass fibre lasers for operation in the mid-infrared wavelength region. We extract the modelling parameters from emission and absorption measurements using Judd-Ofelt and McCumber theory. Numerical algorithms are developed based on the experimentally extracted fibre parameters. The simulation results predict lasing with slope efficiency of at least 20 % provided, that the fibre loss can be kept at the level of 1 dB/m or less

All-fiber, single-mode spectral beam combining of high power Tm-doped fiber lasers

Signal beam combining of Tm-doped fiber lasers can increase the laser output power while simultaneously maintaining the single mode beam quality. We demonstrate an all-fiber integrated dual-wavelength Tm-doped fiber laser with an output power of 36 W by using the spectral beam combining method. The constituent lasers are operating at the wavelengths 1949 and 1996 nm and an in-house-made WDM is used for combination of these two different wavelengths. All-fiber truly single mode power combining is demonstrated for the first time in this wavelength region. © OSA 2015

Single-mode spectral beam combining of high power Tm-doped fiber lasers with WDM cascades

Spectral beam combining of Tm-doped fiber lasers can increase the laser output power while simultaneously maintaining the single mode beam quality. We report on a spectral beam combining technique based on highly efficient in-house-made WDM cascade. We demonstrate continuous wave power combining employing a WDM cascade consisting of four fiber laser sources with emission wavelengths of 1920, 1949, 1996 and 2030 nm. A combined power of up to 38 W resulted in a combining efficiency of 69%. © 2016 SPIE

Clinical and immunologic phenotype associated with activated phosphoinositide 3-kinase δ syndrome 2: A cohort study

Background Activated phosphoinositide 3-kinase δ syndrome (APDS) 2 (p110δ-activating mutations causing senescent T cells, lymphadenopathy, and immunodeficiency [PASLI]–R1), a recently described primary immunodeficiency, results from autosomal dominant mutations in PIK3R1, the gene encoding the regulatory subunit (p85α, p55α, and p50α) of class IA phosphoinositide 3-kinases. Objectives We sought to review the clinical, immunologic, and histopathologic phenotypes of APDS2 in a genetically defined international patient cohort. Methods The medical and biological records of 36 patients with genetically diagnosed APDS2 were collected and reviewed. Results Mutations within splice acceptor and donor sites of exon 11 of the PIK3R1 gene lead to APDS2. Recurrent upper respiratory tract infections (100%), pneumonitis (71%), and chronic lymphoproliferation (89%, including adenopathy [75%], splenomegaly [43%], and upper respiratory tract lymphoid hyperplasia [48%]) were the most common features. Growth retardation was frequently noticed (45%). Other complications were mild neurodevelopmental delay (31%); malignant diseases (28%), most of them being B-cell lymphomas; autoimmunity (17%); bronchiectasis (18%); and chronic diarrhea (24%). Decreased serum IgA and IgG levels (87%), increased IgM levels (58%), B-cell lymphopenia (88%) associated with an increased frequency of transitional B cells (93%), and decreased numbers of naive CD4 and naive CD8 cells but increased numbers of CD8 effector/memory T cells were predominant immunologic features. The majority of patients (89%) received immunoglobulin replacement; 3 patients were treated with rituximab, and 6 were treated with rapamycin initiated after diagnosis of APDS2. Five patients died from APDS2-related complications. Conclusion APDS2 is a combined immunodeficiency with a variable clinical phenotype. Complications are frequent, such as severe bacterial and viral infections, lymphoproliferation, and lymphoma similar to APDS1/PASLI-CD. Immunoglobulin replacement therapy, rapamycin, and, likely in the near future, selective phosphoinositide 3-kinase δ inhibitors are possible treatment options

Wavelength stabilization and mode selection of a GaSb-based semiconductor disk laser at 2 µm by using a volume Bragg grating

Optically pumped semiconductor disk laser (OPSDL) based on the (AlGaIn)(AsSb) unify preferable features from semiconductor and solid state lasers, therefore they can be an excellent source in this wavelength region. To realize this with standard laser setups is quite difficult. For the first time on an OPSDL system in the 2 mum wavelength region with a volume Bragg grating (VBG) as output coupler and for wavelength selection and stabilization is reported. The approximately 10 mum thick monolithically grown OPSDL device structure comprised a high quality AlAsSb/GaSb distributed Bragg reflector with reflectivity >99.5%. For the laser experiments square peaces of 3x3 mm were used. To improve the heat removal from the active region a 0.4 mm thick SiC heat spreader was attached to the surface by liquid capillary bonding

SDL in-band pumped Q-switched 2.1 μm Ho:YAG laser

We demonstrate for the first time to our knowledge a Q-switched Ho:YAG laser in-band pumped by a 1.9 μm semiconductor disk laser (SDL). 3.3 mJ of pulse energy were achieved in a compact setup

Prospective on using fibre mid-infrared supercontinuum laser sources for in vivo spectral discrimination of disease

This is the author accepted manuscript. The final version is available from the Royal Society of Chemistry via the DOI in this record.Mid-infrared (MIR) fibre-optics may play a future role in in vivo diagnosis of disease, including cancer. Recently, we reported for the first time an optical fibre based broadband supercontinuum (SC) laser source spanning 1.3 to 13.4 μm wavelength to cover the spectral ‘fingerprint region' of biological tissue. This work has catalysed the new field of fibre MIR-SC and now very bright sources equivalent to a ‘few synchrotrons' have been demonstrated in fibre. In addition, we have made record transparency MIR fibre for routeing the MIR light and reported first-time MIR photoluminescence (with long lifetime) in small-core, rare earth ion doped, MIR fibre-an important step towards MIR fibre lasing at >4 μm wavelength for pumping fibre MIR-SC. First time fibre MIR-SC spectroscopic imaging of colon tissue is described at wavelengths in the ‘fingerprint region'.EU FP7 programm