An optical device has a gallium and nitrogen containing substrate including a surface region and a strain control region, the strain control region being configured to maintain a quantum well region within a predetermined strain state. The device also has a plurality of quantum well regions overlying the strain control region.

A semiconductor vertical resonant cavity light source includes an upper and lower mirror that define a vertical resonant cavity. An active region is within the cavity for light generation between the upper and lower mirror. At least one cavity spacer region is between the active region and the upper mirror or lower mirror. The cavity includes an inner mode confinement region and an outer current blocking region. An index guide in the inner mode confinement region is between the cavity spacer region and the upper or lower mirror. The index guide and outer current blocking region each include a lower and upper epitaxial material layer thereon with an epitaxial interface region in between. At least a top surface of the lower material layer includes aluminum in the interface region throughout a full area of an active part of the vertical light source.

A semiconductor optical device is provided with a semiconductor substrate that has a length and width, a laser section that is provided on the semiconductor substrate and includes an active layer and an optical waveguide section that is provided adjacent to the laser section on the semiconductor substrate and is joined to the laser section. The optical waveguide section includes a core layer that is connected to an end portion of the active layer, and a pair of cladding layers between which the core layer is sandwiched and emits, from an emission end surface, light incident from the joining interface between the optical waveguide section and the laser section. The semiconductor optical device may be also provided with a reflection suppression layer that is provided on the upper surface of the optical waveguide section.

A semiconductor vertical light source includes upper and lower mirrors with an active region in between, an inner mode confinement region, and an outer current blocking region that includes a common epitaxial layer including an epitaxially regrown interface between the active region and upper mirror. A conducting channel including acceptors is in the inner mode confinement region. The current blocking region includes a first impurity doped region with donors between the epitaxially regrown interface and active region, and a second impurity doped region with acceptors between the first doped region and lower mirror. The outer current blocking region provides a PNPN current blocking region that includes the upper mirror or a p-type layer, first doped region, second doped region, and lower mirror or an n-type layer. The first and second impurity doped region force current flow into the conducting channel during normal operation of the light source.

This invention opens up the chip thickness for increasing VCSEL power. It describes a method by using multiple gain layers 10, separated by insulating layers 11, powered in parallel electrically through embedded electrodes 13, 14 connected through via holes. The gain layers, as a whole, are bounded on top and bottom by DBR mirrors 12. The structure, compared to a standard VCSEL, leads to higher power, lower resistive loss, higher device speed, higher beam quality, and fewer number of DBR layers.

A device and a method for aligning a laser unit to a waveguide unit. The method may include (a) placing the laser unit in a tested position in which the laser unit faces the waveguide unit; (b) supplying light, via a coupler of the waveguide unit, to an alignment waveguide of the waveguide unit; (c) receiving light emitted from the alignment waveguide; wherein the light was emitted as result of the supplying of the light; (d) determining whether the light emitted from the alignment comprises a spectral signature associated with an alignment unit of the laser unit; and (e) estimating whether the laser unit is aligned to the waveguide unit based on the determining of step (d).

A quantum cascade laser includes a first mesa waveguide provided on a substrate, the first mesa waveguide including a first core layer, a second mesa waveguide provided on the substrate, the second mesa waveguide including a second core layer, a first electrode electrically connected to the first mesa waveguide, and a second electrode electrically connected to the second mesa waveguide. The first mesa waveguide and the second mesa waveguide extend in a first direction. The first mesa waveguide and the second mesa waveguide are apart from each other by a first distance in a second direction, the second direction intersecting with the first direction. The first electrode and the second electrode are apart from each other by a second distance. The second distance is larger than the first distance.

A method for increasing the bandwidth of an electroabsorption modulator (EAM) includes the following steps. First, a plurality of p-i-n active waveguides for the EAM are defined on a p-i-n optical waveguide forming an EAM having a shorter p-i-n active waveguide length. Then, the bandwidth of the EAM can be increased. Second, the high-impedance transmission lines are used in series to connect the EAM sections to reduce the microwave reflection and then increase the device bandwidth. Finally, the impedance-controlled transmission lines for the signal input and output can not only reduce the parasitic effects resulting from packaging, but also reduce the microwave reflection resulting from the impedance mismatch at the device input and load.

An optical semiconductor device outputting a predetermined wavelength of laser light includes a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction. The optical semiconductor device includes a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer. The optical semiconductor device further includes an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer. The quantum well active layer is doped with 0.3 to 1×10.sup.18/cm.sup.3 of n-type impurity.

A monolithic integrated semiconductor random laser comprising substrate, lower confinement layer on the substrate, active layer on the lower confinement layer, upper confinement layer on the active layer, strip-shaped waveguide layer longitudinally made in middle of the upper confinement layer, P.sup.+ electrode layer divided into two segments and made on the waveguide layer and N.sup.+ electrode layer on a back face of the lower confinement layer, wherein the two segments correspond respectively to gain region and random feedback region. The random feedback region uses a doped waveguide to randomly feedback light emitted by the gain region and then generates random laser which is random in frequency and intensity. Further, the semiconductor laser is light, small, stable in performance and strong in integration.