A method of controlling a semiconductor element that includes a semiconductor laser diode (LD), a semiconductor modulator, and a semiconductor optical amplifier (SOA) is disclosed. The LD generates CW light supplied with the first bias current. The semiconductor modulator generates a modulated light by modulating the CW light supplied with a driving signal. The SOA generates an optical signal by amplifying the modulated light supplied with the second bias current. The method first sets the second bias current in a region where the output power of the optical signal shows negative dependence of the second bias current. Then, a temperature of the semiconductor element, the first bias current, and the driving signal are adjusted such that the optical signal shows performance in respective preset ranges.

A low-cost, robust method for automatically tuning a coupled resonator to match a wavelength of electromagnetic radiation emitted from an applied laser source. Dithering signals are used for automatic wavelength tuning and thermal stabilization of microring resonators. The disclosed method can be applied using low-speed analog and digital circuitry, to create a complete photonic interconnection network. The methods disclosed also automatically detect, measure, and correct for resonance shift.

A COB bonding laser diode interface mating device comprises a laser diode and a driver integrated circuit (2). The laser diode includes a light-emitting chip (11). The light-emitting chip (11) is a bare die directly bonded to a circuit board. The driver integrated circuit (2) is a driver chip that is a packaged chip. The light-emitting chip (11) and the driver chip are connected through a capacitor-resistor network (3). The capacitor-resistor network (3) allows the driver integrated circuit (2) to provide a bias current and a modulation current to the laser diode such that the laser diode is in an activated state. The capacitor-resistor network (3) realizes interface mating between the COB bonding laser diode and the driver integrated circuit (2), thereby solving a problem that the interface mating cannot be easily achieved, reducing costs, and improving production efficiency.

A laser diode control circuit includes, a control signal supply circuit that supplies a control signal including a direct current component and an alternating current component to a laser diode, an optical output signal acquisition circuit that acquires an optical output signal indicating an optical output of the laser diode according to the control signal, a phase determination circuit that determines whether a phase of the alternating current component included in the optical output signal is the same as the phase of the alternating current component included in the control signal, and a control signal determination circuit that determines to decrease the direct current component of the control signal when it is determined that the phase of the alternating current component included in the optical output signal is not the same as the phase of the alternating current component included in the control signal.

A semiconductor laser is for generating colored light. The semiconductor laser oscillates in a longitudinal multimode. A width of a wavelength band with an intensity equal to or more than 20 dB relative to a peak intensity in a spectrum distribution of output light is equal to or less than 15 nm. A light source device may include The semiconductor laser; a wavelength estimating device configured to estimate a wavelength of light from the semiconductor laser; and an emission-light intensity setting unit configured to set an emission light intensity of the semiconductor laser in accordance with an estimation result by the wavelength estimating device.

A semiconductor laser source includes a partial-grating DFB laser with two laser electrodes, one over the grating and the other between the grating and one end of the laser. Constant laser currents flow into the waveguide through the electrodes (typically different from each other) and produce laser output. A wavelength discriminator, an optical detector, and a wavelength-control circuit act as a wavelength-control feedback mechanism to generate a wavelength control current that flows through one laser electrode or the other, or through both electrodes with opposite polarities. Phase noise on the laser output can be reduced at modulation frequencies exceeding several hundred kHz up to one or several tens of MHz or more. The laser-wavelength can be swept while exhibiting reduced phase noise.

A system for transmitting a sequence of at least two data bursts in a fibre optical communications system includes: selection circuitry configured to select one of a data input value, a logical high value or a logical low value such that the selection circuitry selects the data input value during a data transmission period during a defined burst period and selects one of the logical high value and the logical low value during an extension time period during the defined burst period and immediately following the data transmission period, such that for the sequence of at least two bursts, at least one burst has a logical low value extension period and at least one burst has a logical high value extension period; drive circuitry configured to apply a current to a laser diode, the current corresponding to the value selected by the selection circuitry during the defined burst period or a zero value otherwise, the current being such that the laser diode is configured to provide an optical output; an optical sensor module configured to provide a sensor module output corresponding to the optical output of the laser diode; wherein the sensor module output is configured to provide an electrical output proportional to the laser diode's optical output corresponding to the logical high value and the logical low value in the sequence of at least two bursts, and further configured to provide an output corresponding to an average value of the sensor module output during only the data transmission period during the sequence of bursts; and a controller configured to receive values regarding desired minimum and maximum optical output power levels of the laser diode and to receive the electrical output from the optical sensor module proportional to the optical output power level corresponding to the logical high and the logical low values, and to receive the output corresponding to the average value of the sensor module output during only the data transmission period during the sequence of bursts; wherein the controller is configured to use the received information to provide control values for the drive circuitry.

A semiconductor laser driving circuit that ensures the satisfied extinction ratio, the accuracy of the light output, and enables the light output dynamically to change based on a modulation signal. The semiconductor laser driving circuit includes a semiconductor laser LD of which the laser light is modulated by the analog modulation signal v_MOD, the differential pair circuit having impedance elements 11, 12 and transistors Q1, Q2, a power source 13, a differential driver 22 that generates a differential voltage to switch on-and-off the transistors Q1, Q2 by an analog modulation signal, a threshold electric current generation element that generates the threshold electric current to flow the threshold that the semiconductor laser emits, a slope signal generation element 32 that generates a slope signal V_SLOPE by executing a level conversion by a predetermined slope coefficient relative to the analog modulation signal, and an adder 35 that adds a slope signal, which the slope generation element generates and the threshold electric current that the threshold electric current generation element and controls the electric current or the power source by the addition output.

The present disclosure provides methods and apparatus to improve the dynamic coherent length of a sweep velocity-locked laser pulse generator (SV-LLPG) in an all-electronic fashion. A digital SV-LLPG is disclosed with two operation modes, i.e., unidirectional and bidirectional sweep modes; self-adaptive and time-dependent loop parameters (gain and location of poles/zeros); and, self-adaptive initial input curve. High frequency locking architectures, both single-side band (SSB) modulation method and direct phase measurement method, are provided to suppress the linewidth, or improve the coherent length, of the swept laser. A combination of high and low frequency locking, or a combination of multiple architectures disclosed in this invention, is utilized to achieve a higher level of linewidth reduction. The enhanced laser coherence extends the measurement range by at least one order of magnitude for applications including frequency-modulated continuous wave (FMCW) light detection and ranging (LiDAR) and optical fiber distributed sensing applications.

A wavelength estimation device including a light detector to receive light emitted from a light source and an estimation unit. The estimation unit estimates a wavelength of the light based on an amount of light received by the light detector.