A semiconductor laser tuned with an acousto-optic modulator. The acousto-optic modulator may generate standing waves or traveling waves. When traveling waves are used, a second acousto-optic modulator may be used in a reverse orientation to cancel out a chirp created in the first acousto-optic modulator. The acousto-optic modulator may be used with standing-wave laser resonators or ring lasers.

A laser comprising: at least one wavelength selective reflector that comprises a waveguide vertically coupled to at least one photonic crystal resonator, the waveguide and photonic crystal resonator being arranged to provide wave-vector matching between at least one mode of the photonic crystal resonator and at least one mode of the waveguide; an optical gain medium for generating light for coupling into the waveguide, and a reflector at an end of the optical gain medium, the reflector and the photonic crystal resonator defining a laser cavity. Light generated by the optical gain medium is coupled into the waveguide and coupled into the photonic crystal resonator, and partially reflected back to the optical gain medium.

A laser comprising: at least one wavelength selective reflector that comprises a waveguide vertically coupled to at least one photonic crystal resonator, the waveguide and photonic crystal resonator being arranged to provide wave-vector matching between at least one mode of the photonic crystal resonator and at least one mode of the waveguide; an optical gain medium for generating light for coupling into the waveguide, and a reflector at an end of the optical gain medium, the reflector and the photonic crystal resonator defining a laser cavity. Light generated by the optical gain medium is coupled into the waveguide and coupled into the photonic crystal resonator, and partially reflected back to the optical gain medium.

A semiconductor device manufacturing system includes: a PL evaluation apparatus that evaluates wavelengths of photoluminescent light produced by individual optical modulators on a single semiconductor wafer; an electron beam drawing apparatus that draws patterns of diffraction gratings of laser sections that adjoin respective optical modulators on the wafer; and a calculation section that receives the wavelengths of the photoluminescent light from the PL evaluation apparatus, calculates densities of respective diffraction gratings so that differences between the wavelengths of the photoluminescent light and oscillating wavelengths of the laser sections become a constant, and sends the densities calculated to the electron beam drawing apparatus for drawing respective diffraction grating patterns on the respective laser sections.

A photonic circuit with a hybrid III-V on silicon or silicon-germanium active section, that comprises an amplifying medium with a III-V heterostructure (1, QW, 2) and an optical wave guide. The wave guide comprises a coupling section (31) facing a central portion of the amplifying medium, a propagation section (34, 35) and a modal transition section (32, 33) arranged between the coupling section and the propagation section. In the modal transition section, the optical wave guide widens progressively from the propagation section towards the coupling section.

An edge-emitting semiconductor laser diode chip 15 with mutually opposed front and back end facet mirrors 22, 24. First and second ridges 26.sub.1, 26.sub.2 extend between the chip end facets 22, 24 to define first and second waveguides in an active region layer. Low and high slope efficiency laser diodes are thus formed that are independently drivable by respective electrode pairs 21.sub.1, 23.sub.1 and 21.sub.2, 23.sub.2. The single chip 15 thus incorporates two laser diodes sharing a common heterostructure, one with low slope efficiency optimized for low power operation with good power stability against temperature variations and random threshold current fluctuations in the close-to-threshold power regime, and the other with high slope efficiency optimized for high wall plug efficiency operation at higher output powers when the chip is operating far above threshold.

An edge-emitting semiconductor laser diode chip 15 with mutually opposed front and back end facet mirrors 22, 24. First and second ridges 26.sub.1, 26.sub.2 extend between the chip end facets 22, 24 to define first and second waveguides in an active region layer. Low and high slope efficiency laser diodes are thus formed that are independently drivable by respective electrode pairs 21.sub.1, 23.sub.1 and 21.sub.2, 23.sub.2. The single chip 15 thus incorporates two laser diodes sharing a common heterostructure, one with low slope efficiency optimized for low power operation with good power stability against temperature variations and random threshold current fluctuations in the close-to-threshold power regime, and the other with high slope efficiency optimized for high wall plug efficiency operation at higher output powers when the chip is operating far above threshold.

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.

In the method for controlling a tunable wavelength laser, information designating an oscillation wavelength is inputted. A driving condition for causing laser oscillation at a first wavelength is acquired from a memory. A control value of wavelength characteristics of the etalon and a difference between the first wavelength and a second wavelength are referred to, and a control value of wavelength characteristics of the etalon for causing laser oscillation at the second wavelength is calculated. The control value of wavelength characteristics of the etalon are assigned to the tunable wavelength laser, and a wavelength is controlled so that a wavelength sensing result becomes a first target value. Information indicating a wavelength shift amount from the designated oscillation wavelength is inputted. The wavelength sensing result is calculated as a second target value. The wavelength is controlled so that the wavelength sensing result becomes the second target value.

A tunable transmission optical filter is optically coupled between a laser section and semiconductor optical amplifier (SOA) section of a tunable laser device. The optical filter may be tuned to provide a high transmission near the lasing peak while suppressing a significant portion of back-propagating amplified spontaneous emission (ASE) of the SOA section. Without the optical filter, the laser output spectrum may develop side lobes of higher intensity after the ASE is amplified and reflected in the forward direction by the laser gain and mirror sections. While lessening the side lobes, the optical filter simultaneously transmits the laser peak for amplification by the SOA section.