An optical semiconductor chip of the present disclosure includes a high frequency line between an electrode pad receiving a modulation signal and a modulation electrode on the optical waveguide constituting a laser. The depletion layer capacitance generated in an active layer of the optical waveguide is cancelled by an inductance component of the high frequency line. When a portion directly below the high frequency line is embedded with a low-dielectric-constant material or is made hollow, the parasitic capacitance is further reduced. The high frequency line may have a zigzag shape as well as a linear shape. The electrode pad on the optical semiconductor chip can be connected to other substrates including RF lines for modulation signal input by bumps or wire bonding.

A transmitter circuit, an optical module, and a communications device is disclosed. A transmitter circuit includes a driver and a directly modulated laser DML. A positive electrode of the driver is connected to a positive electrode of the DML, a negative electrode of the DML is connected to a voltage terminal, and the negative electrode of the DML is connected to a ground terminal through a capacitor. The driver is configured to generate a drive current based on an input signal, and output the drive current to the DML through the positive electrode of the driver. The DML inputs a first part of current of the drive current to the ground terminal through the capacitor, and the DML inputs a second part of current of the drive current to the voltage terminal.

An aspect of the present disclosure includes a direct modulated laser (DML) with a dielectric current confinement ridge waveguide (RWG) structure. The DML comprises a substrate, one or more layers of material disposed on the substrate to provide a multi quantum well (MQW), first and second insulation/dielectric structures disposed on opposite sides of the MQW, and one or more layers of material disposed on the MQW to provide a mesa structure for receiving a driving current. The mesa structure is preferably disposed between the first and second insulation structures to provide a dielectric current confinement (RWG) structure. The mesa structure further preferably includes an overall width that is greater than the overall width than the active region of the DML that provides the MQW.

The embodiment relates to a light-emitting device in which a positional relationship between a modified refractive index region's gravity-center position and the associated lattice point differs from a conventional device, and a production method. In this device, a stacked body including a light-emitting portion and a phase modulation layer optically coupled to the light-emitting portion is on a substrate. The phase modulation layer includes a base layer and plural modified refractive index regions in the base layer. Each modified refractive index region's gravity-center position locates on a virtual straight line passing through a corresponding reference lattice point among lattice points of a virtual square lattice on the base layer's design plane. A distance between the reference lattice point and the modified refractive index region's gravity center along the virtual straight line is individually set such that this device outputs light forming an optical image.

An optical modulator carrier assembly includes a optical modulator, a transmission line substrate, a first via, a second via and a wire having an inductor component provided on a second surface of the transmission line substrate, and electrically connecting between the another end of the first via and the another end of the second via. The one end of the first via, the cathode electrode pad, the terminating resistor, the one end of the second via are arranged on the in this order.

An optical semiconductor chip of the present disclosure includes a high frequency line between an electrode pad receiving a modulation signal and a modulation electrode on the optical waveguide having a light absorption layer. The depletion layer capacitance generated in the light absorption layer is canceled by an inductor component of the high frequency line. When a portion directly below the high frequency line is embedded with a low-dielectric-constant material or is made hollow, the parasitic capacitance is further reduced. The high frequency line may have a zigzag shape as well as a linear shape. The electrode pad on the optical semiconductor chip can be connected to other substrates including RF lines for modulation signal input by bumps or wire bonding.

Driver circuitry including an inductor configured to be used both as inductor of a buck convertor, and to provide high-speed pulse driving of a load.

A system and method for providing laser diodes with broad spectrum is described. GaN-based laser diodes with broad or multi-peaked spectral output operating are obtained in various configurations by having a single laser diode device generating multiple-peak spectral outputs, operate in superluminescene mode, or by use of an RF source and/or a feedback signal. In some other embodiments, multi-peak outputs are achieved by having multiple laser devices output different lasers at different wavelengths.

An apparatus includes a plurality of VCSELs, a master laser, one or more electrical drivers, and an optical combiner. The master laser is configured to transmit laser light to the VCSELs to optically lock wavelengths of the VCSELs. The one or more electrical drivers are connected to directly electrically modulate the VCSELs in a manner responsive to one or more digital data stream. The optical combiner is configured to combine light received from, at least, a pair of the VCSELs into an optical carrier with a substantially phase digital data modulation.

Systems and methods for controlling laser modulation in burst communications. In a start-up phase, a drive circuitry sequentially applies first and second drive currents to a laser diode such that it produces a first and second optical output, respectively. A compensating current source coupled to the laser diode provides a current related to the first and second drive currents to maintain a combined current flowing through an impedance connected to the laser diode at a substantially constant level during the start-up phase. An optical sensor measures the first and second optical outputs, and a controller uses values of the first and second drive currents, the outputs from the optical sensor, and at least one supplied input value to provide control values for the drive circuitry for controlling operating current of the laser diode during a subsequent operating phase, wherein information is transmitted in at least one burst.