Abstract: A circuit for generating a clock or sampling signal, the circuit including: a semiconductor quantum dot laser element including a region of quantum dots, wherein the region of quantum dots is characterized by an emission distribution having a half-width of at least about 10 meV; and drive circuitry connected to the quantum dot laser element for operating the quantum dot laser element as a mode-locked laser that outputs a periodic, uniformly spaced sequence of pulses, wherein the clock or sampling signal is derived from the sequence of pulses.

Abstract: An MFA-MOPA that includes a semiconductor laser with separate master oscillator and trumpet-flared power amplifier regions. Within the trumpet-flared active gain region of the uniformly-pumped power amplifier of the MFA-MOPA device, the density distribution of carriers and reflections of the laser beam are analyzed to determine the output powers at which filamentation and beam degradation due to reflections occur. The shape of the trumpet-flare is optimized to delay the onset of filamentation and the degradation of the output laser beam due to reflections to higher output powers for the MFA-MOPA device.

Abstract: A source of electromagnetic radiation including an output, means for generating a drive signal derived from a regenerative feedback signal generated from a portion of said output, further characterized in that an electrical signal obtained from said portion of said output is passed through a narrow bandpass filter in generating said regenerative feedback signal, and means for modulating said electromagnetic radiation within the cavity when the modulating means is driven by said drive signal is disclosed together with a method of generating short pulse electromagnetic radiation signals including operating a electromagnetic radiation source having an output, generating a drive signal derived from a regenerative feedback signal generated from a portion of said output, further characterized in that said portion of said output is passed through a narrow bandpass filter in generating said regenerative feedback signal, and, modulating said electromagnetic radiation, said drive signal derived from a regenerative feed

Abstract: Filtered regenerative feedback is used to modulate a laser or other source of electromagnetic radiation to generate optical pulses whose amplitudes and repetition rates are continuously tunable. The technique is in principle applicable to any source of electromagnetic radiation and is especially effective for semiconductor diode lasers.

Abstract: A wavelength resonant semiconductor gain medium is disclosed. The essential feature of this medium is a multiplicity of quantum-well gain regions separated by semiconductor spacer regions of higher bandgap. Each period of this medium consisting of one quantum-well region and the adjacent spacer region is chosen such that the total width is equal to an integral multiple of 1/2 the wavelength in the medium of the radiation with which the medium is interacting. Optical, electron-beam and electrical injection pumping of the medium is disclosed. This medium may be used as a laser medium for single devices or arrays either with or without reflectors, which may be either semiconductor or external.