Abstract: A transversely-coupled distributed feedback laser diode, which can be processed without overgrowth, is disclosed. The laser is made from an epitaxial heterostructure including a core layer located between two cladding layers, a cap layer, and at least one Al-rich layer. The lateral waveguide is formed by selective oxidation of the Al-rich layer. A surface corrugated grating is formed above the waveguide. The heteroepitaxial structure is designed so that the core layer is placed in close proximity to the top of the laser structure to provide a required overlap between the light and the grating. In order to avoid inadmissible optical losses, there is no metallization above the waveguide. Instead, the metal contacts are offset at some distance, so that the current has to spread in the cap layer before vertical injection into the core layer.

Abstract: A transversely-coupled distributed feedback laser diode, which can be processed without overgrowth, is disclosed. The laser is made from an epitaxial heterostructure including a core layer located between two cladding layers, a cap layer, and at least one Al-rich layer. The lateral waveguide is formed by selective oxidation of the Al-rich layer. A surface corrugated grating is formed above the waveguide. The heteroepitaxial structure is designed so that the core layer is placed in close proximity to the top of the laser structure to provide a required overlap between the light and the grating. In order to avoid inadmissible optical losses, there is no metallization above the waveguide. Instead, the metal contacts are offset at some distance, so that the current has to spread in the cap layer before vertical injection into the core layer.

Abstract: Waveguide designs and fabrication methods provide adiabatic waveguide eigen mode conversion and can be applied to monolithic vertical integration of active and passive elements in PICs. An advantage of the designs and methods is a simple fabrication procedure with only a single etching step in combination with subsequent well-controllable selective oxidation. As a result, improved manufacturability and reliability can be achieved.

Abstract: A semiconductor laser comprises an electrically isolated active section and at least one noise reducing section and operates on a ground state transition of a quantum dot array having inhomogeneous broadening greater than 10 nm. The laser preferably emits more than 10 optical modes such that a total relative intensity noise of each optical mode is less than 0.2% in the 0.001 GHz to 10 GHz range. The spectral power density is preferably higher than 2 mW/nm. An optical transmission system and a method of operating a quantum dot laser with low relative intensity noise of each optical mode are also disclosed.

Abstract: Waveguide designs and fabrication methods provide adiabatic waveguide eigen mode conversion and can be applied to monolithic vertical integration of active and passive elements in PICs. An advantage of the designs and methods is a simple fabrication procedure with only a single etching step in combination with subsequent well-controllable selective oxidation. As a result, improved manufacturability and reliability can be achieved.

Abstract: An optical transmission system includes a laser, a transmitter and a receiver. The laser is capable of operating on an inhomogeneously broadened optical transition of the active region of the laser. A spectral bandwidth of an output lasing spectrum of the laser is greater than 5 nm and a spectral power density of the laser is greater than 2 mW/nm such that an optical power of the laser is greater than 10 mW. The laser provides a plurality of optical signals at different wavelengths. The transmitter is capable of providing modulation to each lasing wavelength independently and the receiver is capable of providing detection to each lasing wavelength independently.

Abstract: A semiconductor laser comprises an electrically isolated active section and at least one noise reducing section and operates on a ground state transition of a quantum dot array having inhomogeneous broadening greater than 10 nm. The laser preferably emits more than 10 optical modes such that a total relative intensity noise of each optical mode is less than 0.2% in the 0.001 GHz to 10 GHz range. The spectral power density is preferably higher than 2 mW/nm. An optical transmission system and a method of operating a quantum dot laser with low relative intensity noise of each optical mode are also disclosed.

Abstract: A quantum dot laser operates on a quantum dot ground-state optical transition. The laser has a broadband (preferably ?15 nm) spectrum of emission and a high output power (preferably ?100 mW). Special measures control the maximum useful pump level, the total number of quantum dots in the laser active region, the carrier relaxation to the quantum dot ground states, and the carrier excitation from the quantum dot ground states. In one embodiment, a spectrally-selective loss is introduced into the laser resonator in order to suppress lasing on a quantum dot excited-state optical transition, thereby increasing the bandwidth of the emission spectrum.

Abstract: An optical transmission system includes a laser, a transmitter and a receiver. The laser is capable of operating on an inhomogeneously broadened optical transition of the active region of the laser. A spectral bandwidth of an output lasing spectrum of the laser is greater than 5 nm and a spectral power density of the laser is greater than 2 mW/nm such that an optical power of the laser is greater than 10 mW. The laser provides a plurality of optical signals at different wavelengths. The transmitter is capable of providing modulation to each lasing wavelength independently and the receiver is capable of providing detection to each lasing wavelength independently.

Abstract: A quantum dot laser operates on a quantum dot ground-state optical transition. The laser has a broadband (preferably ?15 nm) spectrum of emission and a high output power (preferably ?100 mW). Special measures control the maximum useful pump level, the total number of quantum dots in the laser active region, the carrier relaxation to the quantum dot ground states, and the carrier excitation from the quantum dot ground states. In one embodiment, a spectrally-selective loss is introduced into the laser resonator in order to suppress lasing on a quantum dot excited-state optical transition, thereby increasing the bandwidth of the emission spectrum.

Abstract: A monolithic mode-locked diode laser with improved uniformity of light distribution along the cavity. The laser includes a multiple gain section with more than one gain subsection where the length of each subsection is less than the reciprocal gain coefficient in the gain subsection and a multiple saturable absorber section with more than one saturable absorber subsection where the length of each subsection is less than the reciprocal absorption coefficient in the saturable absorber subsection. The gain subsections alternate with the saturable absorber subsections and are optically coupled in a single waveguide. They are also allocated inside the monolithic cavity such that the total length of the gain subsections and the saturable absorber subsections is equal or close to the total cavity length. The cavity length preferably corresponds to a sufficiently low fundamental repetition frequency. Special measures are preferably provided to ensure mode-locking at the fundamental frequency.