In an embodiment, a laser includes a gain section. The gain section includes an active region, an upper separate confinement heterostructure (SCH), and a lower SCH. The upper SCH is above the active region and has a thickness of at least 60 nanometers (nm). The lower SCH is below the active region and has a thickness of at least 60 nm.

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.

A vertical-cavity surface-emitting laser diode includes: a first resonator that has a plurality of semiconductor layers comprising a first current narrowing structure having a first conductive region and a first non-conductor region; a first electrode that supplies electric power to drive the first resonator; a second resonator that has a plurality of semiconductor layers comprising a second current narrowing structure having a second conductive region and a second non-conductive region and that is formed side by side with the first resonator, the second current narrowing structure being formed in same current narrowing layer as the layer where the first current narrowing structure is formed; and a coupling portion as defined herein; and an equivalent refractive index of the coupling portion is smaller than an equivalent refractive index of each of the first resonator and the second resonator.

A tunable laser for tuning a lasing mode based on light beams travelling through at least one block of channel waveguides with at least two tunable combs, includes: a frequency selective optical multiplexer comprising a first terminal for receiving/transmitting light, at least one block of channel waveguides, each channel waveguide having a reflectively coated first tail and a second tail, and an optical coupling element optically coupling the first terminal with the second tails of the channel waveguides of the at least one block of channel waveguides, each of the channel waveguides having a different length; a gain element generating a broad spectrum of light, the gain element coupling the first terminal of the frequency selective optical multiplexer with a reflective element.

The DML driver includes: a post driver which supplies a driving current to the LD; and a pre-driver which drives the post driver in response to a modulated signal. The pre-driver has a transistor, a peaking inductor, a peaking inductor, a group delay inhibition inductor, and a peaking capacitor.

Method and gas analyzer for measuring the concentration of a gas component in a sample gas, wherein to measure the concentration of a gas component in a sample gas, a laser diode is actuated by a current and light generated by the laser diode is guided through the sample gas to a detector, the current is simultaneously varied within periodically successive sampling intervals for the wavelength-dependent sampling of an absorption line of interest of the gas component, and the current can be additionally modulated sinusoidally based on wavelength modulation spectroscopy with a low frequency and small amplitude, such that a measuring signal generated by the detector is evaluated to form a measurement result, where to improve the measuring signal-noise ratio and achieve a much lower detection limit with the same measuring distance, the current is modulated with a high (RF) frequency in the GHz range so that no wavelength modulation occurs, and an RF modulation amplitude is selected at the maximum level using the linear control range of the laser diode where, before evaluation, the measuring signal is demodulated at the radio frequency.

Integrated circuitry is fabricated from semiconductor layers formed on a substrate, which include at least one n-type layer, an inverted p-type modulation doped quantum well (mod-doped QW) structure, a non-inverted n-type mod-doped QW structure, and at least one p-type layer including a first P+-type layer formed below a second P-type layer. An etch operation exposes the second p-type layer. P-type ions are implanted into the exposed second p-type layer. A gate electrode of a n-channel HFET device is formed in contact with the p-type ion implanted region. Source and drain electrodes of the n-channel HFET device are formed in contact with n-type ion implanted regions formed in contact with the n-type mod-doped QW structure. P-channel HFET devices, complementary BICFET devices, stacked complementary HFET devices and circuits and/or logic gates based thereon, and a variety of optoelectronic devices and optical devices can also be formed as part of the integrated circuitry.

The present disclosure provides a narrow-pulse-width pulse laser, including a circuit substrate, a laser chip, one or more capacitors, and a field effect transistor. Each of the field effect transistor, the capacitor, and the laser chip is electrically connected to the circuit substrate. The capacitors are arranged between the field effect transistor and the laser chip along an extension direction of a gap between the field effect transistor and the laser chip. The circuit substrate may include a first conductor layer; a second conductor layer; and an insulating layer arranged between the first conductor layer and the second conductor layer, wherein the first conductor layer and the second conductor layer are electrically connected through a via hole in the insulating layer.

An optoelectronic oscillator for generating an optical and/or electric pulse comb, comprising a monolithically integrated passively mode-coupled semiconductor laser and an optical feedback loop which guides a part of the optical radiation of the semiconductor laser and feeds said part back into the semiconductor laser as feedback pulses. Without the influence of the feedback pulses, the semiconductor laser would emit comb-like optical pulses, hereafter referred to as primary pulses, and in the event of an influence, emits comb-like output pulses which have been influenced by the feedback pulses, said output pulses having a lower temporal jitter or less phase noise than the primary pulses. The feedback loop is damped between 27.5 and 37.5 dB, and the time lag of the feedback loop is selected such that each feedback pulse is incident within the temporal half-value width of each subsequent primary pulse.

Various optical systems equipped with diode laser light sources are discussed in the present application. One example system includes a diode laser light source for providing a beam of radiation. The diode laser has a spectral output bandwidth when driven under equilibrium conditions. The system further includes a driver circuit to apply a pulse of drive current to the diode laser. The pulse causes a variation in the output wavelength of the diode laser during the pulse such that the spectral output bandwidth is at least two times larger than the spectral output bandwidth under the equilibrium conditions.