Exalos Ag

Marcus Pierre Dülk

Christian Velez

Marco Rossetti

Antonino Francesco Castiglia

Jean Dahdah

Stefan Gloor

Nikolay Primerov

Marco Malinverni

Rainer Leitgeb

Philipp Vorreau

Nicolai Matuschek

Laurin Ginner

A module accommodates multiple superluminescent light emitting diodes, SLEDs,and. The SLEDs are arranged in an enclosure and output respective light beams to propagate into free space within the enclosure. The individual light beams from the SLED sources are combined into a single beam path within the enclosure using beam combiners--. Each beam combiner is realized as a planar optical element, the back side of which is arranged to receive a SLED beam and route it through the optical element to the front side where it is combined with another SLED beam that is incident on and reflected by the front side. The free-space propagating combined beam is output from the module via an optical fiber(or through a window).

Superluminescent diode module

An amplified spontaneous emission, ASE, source device combining a superluminescent light emitting diode, SLED, with a semiconductor optical amplifier, SOA, the SLED and SOA being arranged in series so that the SLED acts as a seed and the SOA acts as a broadband amplifier for the SLED output. Both SLED and SOA have a structure made up of a succession of epitaxial semiconductor layers which form a waveguide comprising a core of active region layers and surrounding cladding layers. The SLED and SOA confinement factors of the SLED and SOA, wherein confinement factor is the percentage of the optical mode power in the active region layers, is designed so that the SLED confinement factor is greater than that of the SOA by at least 20%. This allow higher power outputs, because the SLED power limits imposed by the onset of non-linear effects and catastrophic optical damage can be circumvented.

Amplified spontaneous emission semiconductor source

An edge-emitting semiconductor laser diode chipwith mutually opposed front and back end facet mirrors. First and second ridgesextend between the chip end facetsto define first and second waveguides in an active region layer. Low and high slope efficiency laser diodes are thus formed that are independently drivable by respective electrode pairsand. The single chipthus incorporates two laser diodes sharing a common heterostructure, one with low slope efficiency optimized for low power operation with good power stability against temperature variations and random threshold current fluctuations in the close-to-threshold power regime, and the other with high slope efficiency optimized for high wall plug efficiency operation at higher output powers when the chip is operating far above threshold.

Edge-emitting laser diode with improved power stability

Superluminescent light emitting diode, SLED, devices and modules are provided. A multi-wavelength SLED device is fabricated by sequentially depositing adjacent epitaxial stacks onto a substrate to form a monolithic chip structure. Each epitaxial stack includes n-type layers, active layers and p-type layers. A ridge is formed in the p-type layers between the end facets of the chip to induce a waveguiding region in the active layers. Different ones of the epitaxial stacks emit at different wavelength ranges. A module is made by packaging one of the above SLED devices with another SLED device, with one inverted relative to the other to form a triangle of emitters as viewed end on, for example a triangle of red, green and blue emitters. The SLED devices and modules may find use in projection, endoscopic, fundus imaging and optical coherence tomography systems.

Superluminescent diodes and diode modules

A source module suitable for an optical coherence tomography system. The source module comprises a source operable to emit a divergent, source output beam either of circular cross-section (e.g. as output by a vertical cavity surface emitting laser) or of elliptical cross-section (e.g. as output by an edge-emitting semiconductor laser or diode). Collimation optics are provided to convert the source output beam into a non-divergent, collimated beam of elliptical cross-section having a major axis and a minor axis. A cylindrical lens is arranged with its plano axis aligned with the major axis of the elliptical collimated beam and its power axis aligned with the minor axis of the elliptical collimated beam so as to form a line focus extending along the major axis of the elliptical collimated beam.

Source module and optical system for line-field imaging

A depolarizer for a broadband optical source to split the source beam by power, not by polarization state, and route the components into respective light paths. A polarization rotator arranged in one of the light paths rotates the polarization state of that beam component to make it orthogonal to that of the other. The components are then recombined by a combiner and output. A variable optical attenuator is arranged in one of the light paths, which during operation is adjusted by a controller to maintain power equalization between the light paths and hence depolarization performance. The controller receives power measurements from the light paths and from after the combiner via respective sensors. With this feedforward design reminiscent of a Mach-Zehnder interferometer the light from a light source which generates highly polarized light can be depolarized in theory with zero insertion loss and in practice with losses of about 1 dB.

Depolarizers

A low power, side-emitting semiconductor laser diode is provided. The laser diode is formed from a semiconductor heterostructure having an active layer sandwiched between an n-type layer and a p-type layer, wherein the active layer forms a gain medium of width W. Front and back reflectors of reflectivity Rf and Rb are arranged on opposing side facets of the semiconductor heterostructure part to form a cavity of length L containing at least a part of the active layer which thus forms the gain medium for the laser diode, the gain medium having an internal loss &#x3b1;i. To achieve stable, low power operation close to threshold, the laser diode is configured with the following parameter combination: width W: 1 &#x3bc;m&#x2264;W&#x2264;2 &#x3bc;m; cavity length L: 100 &#x3bc;m&#x2264;L&#x2264;600 &#x3bc;m; internal loss &#x3b1;i: 0 cm&#x2264;&#x3b1;i&#x2264;30 cm; back reflectivity Rb: 100&#x2265;Rb&#x2265;80%; and front reflectivity Rf: 100&#x2265;Rf&#x2265;60%.

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Schlieren, Switzerland

Marcus Pierre Dülk