A sweeping signal generating device includes a first converter that outputs a sweeping signal having a first offset value added to or subtracted from a sweeping standard level, a second converter that outputs an offset signal having a second offset value corresponding to the first offset value, and an adder circuit that adds the sweeping signal output from the first converter and the offset signal output from the second converter.

A technique for narrowing a linewidth of a plurality of lines of a coherent comb laser (CCL) concurrently comprises providing a mode-locked semiconductor coherent comb laser (CCL) adapted to output of at least 4 mode-locked lines; tapping a fraction of a power from the CCL from the laser cavity to form a tapped beam; propagating the tapped beam to an attenuator to produce an attenuated beam; and reinserting the attenuated beam into the laser cavity, where the reinserted beam has a power less than 10% of a power of the tapped beam. The reinsertion allows the CCL to be operated to output the mode-locked lines, each with a linewidth of less than 80% of the original linewidth. By propagating the tapped and attenuated beams on a solid waveguide, and ensuring that the secondary cavity is polarization maintaining, improved stability of the linewidth narrowing is ensured.

A technique for narrowing a linewidth of a plurality of lines of a coherent comb laser (CCL) concurrently comprises providing a mode-locked semiconductor coherent comb laser (CCL) adapted to output of at least 4 mode-locked lines; tapping a fraction of a power from the CCL from the laser cavity to form a tapped beam; propagating the tapped beam to an attenuator to produce an attenuated beam; and reinserting the attenuated beam into the laser cavity, where the reinserted beam has a power less than 10% of a power of the tapped beam. The reinsertion allows the CCL to be operated to output the mode-locked lines, each with a linewidth of less than 80% of the original linewidth. By propagating the tapped and attenuated beams on a solid waveguide, and ensuring that the secondary cavity is polarization maintaining, improved stability of the linewidth narrowing is ensured.

A laser frequency control apparatus comprising: (a) a laser; (b) an oscillator configured to receive an output of the laser and to output a modulated signal; (c) a frequency reference configured to receive the modulated signal and to provide an output signal; and (d) a mixer configured to mix at least a portion of the output signal with an output of the oscillator to generate a mixer output, wherein the mixer output is injected to a section of the laser.

An integrated optical transceiver, comprising a laser component, comprising an array of VCSEL diodes formed on a laser diode substrate; a laser driving component, comprising laser diode driving circuitry formed on a laser driving circuitry substrate; a photodiode component, comprising an array of photodiodes formed on a photodiode substrate; and a photodiode driving component, comprising photodiode driving circuitry formed on a photodiode driving circuitry substrate; a first heat sink comprising a connected piece of material to transport excess heat away from the integrated optical transceiver and connected to both the laser and photodiode driving components; and an electrically insulating material separating the photodiode substrate from the first heat sink and being air or dielectric material with a relative dielectric constant <10, wherein the electrically insulating material provides a gap having an effective electrical distance of at least 80 m between the photodiode substrate and the first heat sink.

Examples disclosed herein relate to multi-wavelength semiconductor lasers. In some examples disclosed herein, a multi-wavelength semiconductor laser may include a silicon-on-insulator (SOI) substrate and a quantum dot (QD) layer above the SOI substrate. The QD layer may include and active gain region and may have at least one angled junction at one end of the QD layer. The SOI substrate may include a waveguide in an upper silicon layer and a mode converter to facilitate optical coupling of a lasing mode to the waveguide.

The present disclosure provides a unique digitally integrated, self-trained pre-distortion curve generation method and apparatus for semiconductor lasers (SCLs) to generate linearly swept optical signals that are applicable to a wide range of sweep velocities and semiconductor laser types. The method requires no prior knowledge of the frequency response of the laser and is highly accurate.

Examples disclosed herein relate to multi-wavelength semiconductor lasers. In some examples disclosed herein, a multi-wavelength semiconductor laser may include a silicon-on-insulator (SOI) substrate and a quantum dot (QD) layer above the SOI substrate. The QD layer may include and active gain region and may have at least one angled junction at one end of the QD layer. The SOI substrate may include a waveguide in an upper silicon layer and a mode converter to facilitate optical coupling of a lasing mode to the waveguide.

The optical mode of a photonic device is coupled between a first region made of a semiconducting material, and a second region made of a dielectric material. Photons are generated within the first region, while the optical mode is predominantly stored within the second region. The thickness of the first region and its width are controlled to determine its effective refractive index, enabling control of the optical mode.

Examples disclosed herein relate to quantum-dot (QD) photonics. In accordance with some of the examples disclosed herein, a QD semiconductor optical amplifier (SOA) may include a silicon substrate and a QD layer above the silicon substrate. The QD layer may include an active gain region to amplify a lasing mode received from an optical signal generator. The QD layer may have a gain recovery time such that the active gain region amplifies the received lasing mode without pattern effects. A waveguide may be included in an upper silicon layer of the silicon substrate. The waveguide may include a mode converter to facilitate optical coupling of the received lasing mode between the QD layer and the waveguide.