摘要:
A semiconductor pump laser uses a depolarzer to depolarize the pump light entering the fiber amplifier. The depolarized light source is useful for reducing polarization dependent gain of fiber amplifiers. The pump laser includes one or more semiconductor, coherence-collapsed laser sources emitting polarized pump outputs, and one or more depolarizers disposed to depolarize the polarized pump output from the lasers. One or more fiber outputs are coupled to the one or more depolarizers to receive depolarized pump light. The depolarizer may include an N×M polarization preserving coupler having N inputs and M outputs, N and M being at least 2, an input to the depolarizer at a first coupler input, an output port from the depolarizer at a first coupler output. A polarization-controlling optical path is coupled between a second coupler output and a second coupler input. A polarization of light exiting the N×M coupler through the second coupler output is substantially orthogonal to a polarization of light entering the N×M coupler through the second coupler input.
摘要:
Optical pumping arrangements are provided for the broadband or multiple wavelength pumping of optical sources. Sources may be based on Raman gain media and may use multiple output couplers to couple out different wavelength ranges. Cascaded Raman resonator (CRR) configurations may also be used. Overlapping resonators at different wavelengths may be configured to share gain media, and may have separate portions in separate optical paths. Attenuation filters may also be used that are matched to the gain profile of a gain medium, to flatten the gain spectrum and allow equalization of gain to different output wavelengths. In one embodiment, polarization maintaining fiber is used to develop resonant conditions at different wavelengths in different polarization states. Wideband output gratings may be substituted for narrowband gratings to provide CRR configurations with a broader output band. Broadband amplification may also be provided by using a laser source operating in coherence collapse. The multiple wavelength pumping lends itself to a pumping arrangement in which sources at different wavelengths are combined into separate transmission/gain media such as the different fibers of an optical fiber cable.
摘要:
A pump source for a fiber Raman amplifier uses multiple lasers to generate high pump power or to generate a pump beam having a tailored spectrum for producing a desired Raman gain spectral profile. Light from two lasers, in mutually orthogonal polarization states directed to a polarization combiner that produces an output having light mixed at the two orthogonal polarization states. A depolarizer depolarizes the output. The depolarizer defines first and second orthogonal polarization modes oriented so that the light output from the polarization combiner in one polarization state excites the first and second polarization modes of the depolarizer equally and the light output from the polarization combiner in the other polarization state also excites the first and second polarization modes of the depolarizer equally.
摘要:
A buried heterostructure (BH) laser source with a narrow active region is disclosed for use in close proximity with optically-addressed data storage media for read/write functionality in a relatively high data density format. The BH laser source is formed on a pregrooved or prepatterned substrate to form mesas upon which epitaxial layers are formed to form laser source active regions that have small emission apertures at the laser source facet output. Selective removal of semiconductor cladding material and replacement of this material with lower refractive index materials provides a way of obtaining further mode size-reduction at the output facet of the laser source. Each mesa has a top surface and adjacent sidewalls such that in the growth of the epitaxial layers above the active region doped with a first conductivity type, the above active region epitaxial layers depositing on the top surface deposit as a first conductivity type and depositing on said sidewalls deposit as a second conductivity type. This growth construction provides for a naturally formed p-n junction at the laser source active region and eliminates the need to perform a subsequent diffusion process to form such a junction. The optical cavities of the laser sources may be tapered so that die cleaving a predetermined point along the length of the optical cavity will provide the desired emission aperture size at the laser source output facet.
摘要:
An optical amplifier with a flattened wideband response is obtained by coupling counter-propagating pumping energy into an optical waveguide to cause Raman amplification in the optical waveguide, and by reflecting an amplified signal received from the optical waveguide into an output waveguide using a reflector having a spectral characteristic that is complementary to the spectral gain characteristic of the Raman amplification.
摘要:
An optical amplifier with a flattened wideband response is obtained by coupling counter-propagating pumping energy into an optical waveguide to cause Raman amplification in the optical waveguide, and by reflecting an amplified signal received from the optical waveguide into an output waveguide using a reflector having a spectral characteristic that is complementary to the spectral gain characteristic of the Raman amplification.
摘要:
Optical pumping arrangements are provided for the broadband or multiple wavelength pumping of optical sources. Sources may be based on Raman gain media for amplification. Broadband amplification is provided by using a laser source operating in coherence collapse. Such a source may make use of an optical generator and an output coupler which are sufficiently far apart from one another as to ensure coherence collapse.
摘要:
An electrostatically controlled cantilever apparatus for continuous tuning of the resonance wavelength of a Fabry-Perot cavity is disclosed. A resonant cavity is formed between two distributed Bragg reflector (DBR) mirrors. The top reflector is composed of a movable top DBR supported in a freely suspended cantilever, a variable-thickness air spacer layer and a fixed DBR. The bottom reflector is fixed on the substrate. By applying a tuning voltage to create electrostatic attraction, the cantilever may be deflected towards the substrate, thereby changing the thickness of the air spacer layer and consequently the resonant wavelength of the Fabry-Perot cavity.
摘要:
One or more single mode waveguide devices are fiber coupled such that signals to an optical element affect the coupling of the waveguide device to one or more modulators and to an optical fiber. The optical element or additional optical elements are controlled to adjust the coupling of the waveguide device to a modulator and to an optical fiber.
摘要:
A photonic device including an array of lasers providing light to an array of electro-absorption modulators, both on a common substrate. In some embodiments the lasers are in a closely spaced array and lase at different wavelengths, providing with associated electro-absorption modulators a compact wavelength selectable laser.