An apparatus and method are provided. In particular, at least one first electro-magnetic radiation may be provided to a sample and at least one second electro-magnetic radiation can be provided to a non-reflective reference. A frequency of the first and/or second radiations varies over time. An interference is detected between at least one third radiation associated with the first radiation and at least one fourth radiation associated with the second radiation. Alternatively, the first electro-magnetic radiation and/or second electro-magnetic radiation have a spectrum which changes over time. The spectrum may contain multiple frequencies at a particular time. In addition, it is possible to detect the interference signal between the third radiation and the fourth radiation in a first polarization state. Further, it may be preferable to detect a further interference signal between the third and fourth radiations in a second polarization state which is different from the first polarization state. The first and/or second electro-magnetic radiations may have a spectrum whose mean frequency changes substantially continuously over time at a tuning speed that is greater than 100 Tera Hertz per millisecond.

A apparatus includes a tunable laser configured to include a tunable filter and a mirror; a first optical splitter provided between the tunable filter and the mirror, the first optical splitter including a first port and a second port on a tunable filter side and a third port and a fourth port on a mirror side, in which the tunable filter is coupled to the first port and the mirror is coupled to the third port, respectively; a first optical waveguide coupled to the second port; a second optical waveguide coupled to the fourth port; and an optical coupler with which the first optical waveguide and the second optical waveguide are combined.

An external resonator type light-emitting device includes a light source oscillating a semiconductor laser light and a grating element configuring an external resonator together with the light source. The light source includes an active layer oscillating the semiconductor laser light. The grating element includes an optical waveguide and a plurality of Bragg gratings formed in the optical waveguide. The optical waveguide includes an incident face on which the semiconductor laser light is incident and an emitting face from which an emitting light having a desired wavelength is emitted.

An external resonator type light-emitting device includes a light source oscillating a semiconductor laser light and a grating element configuring an external resonator together with the light source. The light source includes an active layer oscillating said semiconductor laser light. The grating element includes an optical waveguide and a plurality of Bragg gratings formed in the optical waveguide. The optical waveguide includes an incident face to which the semiconductor laser light is incident and an emitting face from which an emitting light having a desired wavelength is emitted. A half value reflectance R.sub.50 is larger than a reflectance R.sub.2 at an emitting end of the light source. A half value reflectance R.sub.50 is 3% or larger. A combined reflectance is not less than the half value reflectance R.sub.50 in a wavelength region .sub.50. The wavelength region .sub.50 is continuous over 10 nm or more and 30 nm or less, provided that a half value reflectance is defined as 50 percent of a maximum value Rmax of the combined reflectance of the Bragg gratings.

A laser assembly includes a set of one or more substrates having a first surface opposite a second surface. The set of one or more substrates defines a resonant cavity extension. The resonant cavity extension extends into the set of one or more substrates from an opening in the first surface. The laser assembly further includes a first reflector disposed within the resonant cavity extension and configured to reflect at least one wavelength of electromagnetic radiation received through the opening back through the opening; a laser having an active region configured to generate the at least one wavelength of electromagnetic radiation; and a second reflector. The active region is disposed in a resonant cavity extending between the first reflector and the second reflector. The resonant cavity includes the resonant cavity extension.

The invention describes a laser device (100) enabling controlled emission of individual laser beams (194). The laser device (100) comprises an optically pumped extended cavity laser with one gain element whereby a multitude of pump lasers (110) are provided in order to generate independent pump beams (191) and thus corresponding laser beams (194). The laser device (100) may be used to enable simplified or improved laser systems (500) as, for example, two or three-dimensional laser printers. The pump laser (110) may be VCSEL and the laser (160) may be a VECSEL monolithically integrated with the pump VCSEL array on the same substrate. Pump mirrors (140) and external cavity mirror (150) may be integrated into a single optical reflector with regions having different curvature. The laser emission is controlled by the pump light, i.e. transversal shape of the laser beam and/or number of laser beams is controlled by switching on/off the individual pump lasers (110).

An emitting device is intended for delivering photons with a chosen wavelength. This emitting device includes an InP substrate with a directly modulated laser arranged for generating photons modulated by a non-return-to-zero modulation to produce data to be transmitted, a passive ring resonator monolithically integrated with the directly modulated laser and having a resonance amongst several ones that is used for filtering a zero level induced by the data modulation, and a tuning means arranged along the directly modulated laser and/or around the ring resonator to tune the photon wavelength and/or the ring resonator resonance used for filtering.

A broad area semiconductor laser device includes a waveguide region and a filter region. The waveguide region includes an active region into which current is injected, and a cladding region that sandwiches the active region. The active region either protrudes or is recessed with respect to the filter region, so as to promote the divergence of higher order modes in the filter region.

A broad area semiconductor laser device includes a waveguide region and a filter region. The waveguide region includes an active region into which current is injected, and a cladding region that sandwiches the active region. The active region either protrudes or is recessed with respect to the filter region, so as to promote the divergence of higher order modes in the filter region.

A light source having a gain chip, a retro reflecting prism and a first actuator is disclosed. The gain chip amplifies light passing therethrough. The retro reflecting prism is characterized by a pivot axis within the retro reflecting prism, an input light direction, an output light direction, and a diffraction grating that receives light emitted by the gain chip traveling in the input direction, returns a diffracted light beam to the gain chip along the input light direction and generates an output light beam. The first actuator causes the retro reflecting prism to rotate about the pivot axis in response to a control signal being coupled to the first actuator.