Abstract: The present disclosure is generally directed to an EML with a filter layer disposed between an active region of the EML and a substrate of the EML to absorb a portion of unmodulated light energy, and preferably the unmodulated light energy caused by transverse electric (TE) substrate mode. The filter layer preferably comprises a material with an energy band gap (Eg) that is less than the energy band gap of the predetermined channel wavelength to absorb unmodulated laser light.

Abstract: A multi-section semiconductor optical amplifier (SOA) includes at least two sections in series—an input section at an input side and an output section at an output side—with the input section having a higher optical confinement (also referred to as a high gamma) and the output section having a lower optical confinement (also referred to as a low gamma). The input section may also have a shorter length than the output section. The multi-section structure allows optimizing the input side and the output side design separately such that the input section provides a high gain section configured to quickly increase optical power and the output section provides a low differential gain section that improves saturation. As a result, the multi-section SOA can achieve higher output power with high gain and lower signal noise while demanding low input power.

Abstract: A semiconductor optical device including a buried heterostructure (BH) has reduced parasitic capacitance and reduced inter-diffusion. The semiconductor optical device is manufactured by a regrowth on both sides of a mesa structure with an Fe-doped current blocking layer and an n-type cladding layer outside of an active region in the mesa structure. The Fe-doped current blocking layer and the n-type cladding layer may be disposed and configured such that Fe/Zn inter-diffusion is reduced or prevented by minimal contact between the Fe-doped current blocking layer and a highly Zn-doped cladding layer and by the n-type cladding layer, as will be described in greater detail below. A low Zn-doped or undoped material may be used for a thin cladding layer above the active region in the mesa structure to further suppress Zn/Fe inter-diffusion.

Abstract: An aspect of the present disclosure includes a direct modulated laser (DML) with a dielectric current confinement ridge waveguide (RWG) structure. The DML comprises a substrate, one or more layers of material disposed on the substrate to provide a multi quantum well (MQW), first and second insulation/dielectric structures disposed on opposite sides of the MQW, and one or more layers of material disposed on the MQW to provide a mesa structure for receiving a driving current. The mesa structure is preferably disposed between the first and second insulation structures to provide a dielectric current confinement (RWG) structure. The mesa structure further preferably includes an overall width that is greater than the overall width than the active region of the DML that provides the MQW.

Abstract: The present disclosure is generally directed to an EML with a filter layer disposed between an active region of the EML and a substrate of the EML to absorb a portion of unmodulated light energy, and preferably the unmodulated light energy caused by transverse electric (TE) substrate mode. The filter layer preferably comprises a material with an energy band gap (Eg) that is less than the energy band gap of the predetermined channel wavelength to absorb unmodulated laser light.

Abstract: In general, a MQW semiconductor laser chip with an electrically insulated P-side region and a process for forming the same is disclosed. The MQW semiconductor laser chip, also referred to herein as a MQW semiconductor laser or simply a semiconductor laser, includes a layer of electrically insulative material that extends along at least a portion of the sidewalls to minimize or otherwise reduce the potential for electrical shorts between P and N-sides of the same when utilizing P-side bonding techniques.

Abstract: A tunable laser with multiple in-line sections including sampled gratings generally includes a semiconductor laser body with a plurality of in-line laser sections configured to be driven independently to generate laser light at a wavelength within a different respective wavelength range. Sampled gratings in the respective in-line sections have the same grating period and a different sampling period to produce the different wavelengths. The wavelength of the light generated in the respective laser sections may be tuned, in response to a temperature change, to a channel wavelength within the respective wavelength range. By selectively generating light in one or more of the laser sections, one or more channel wavelengths may be selected for lasing and transmission. By using sampled gratings with the same grating period in the multiple in-line sections, the multiple section tunable laser may be fabricated more easily.

Abstract: A two-section semiconductor laser includes a gain section and a modulation-independent grating section to reduce chirp. The modulation-independent grating section includes a diffraction grating for reflecting light and forms a laser cavity with the gain section for lasing at a wavelength or range of wavelengths reflected by the diffraction grating. The gain section of the semiconductor laser includes a gain electrode for driving the gain section with at least a modulated RF signal and the grating section includes a grating electrode for driving the grating section with a DC bias current independent of the modulation of the gain section. The semiconductor laser may thus be directly modulated with the modulated RF signal without the modulation significantly affecting the index of refraction in the diffraction grating, thereby reducing chirp.

Abstract: Individual channels of a multiplexed laser array in a multi-channel optical transmitter are monitored at an output of an optical multiplexer. The monitoring may be used to confirm proper operation of each of the channels in the multiplexed laser array and/or to perform wavelength locking on each of the channels. Monitoring at the output of the optical multiplexer avoids the use of multiple photodetectors coupled directly to multiple lasers in the multiplexed laser array. The multiplexed laser array generally includes a plurality of laser emitters optically coupled to an optical multiplexer such as an arrayed waveguide grating (AWG). An optical transmitter with a monitored multiplexed laser array may be used, for example, in an optical line terminal (OLT) in a wavelength division multiplexed (WDM) passive optical network (PON) or in any other type of WDM optical communication system capable of transmitting optical signals on multiple channel wavelengths.

Abstract: A two-section semiconductor laser includes a gain section and a modulation-independent grating section to reduce chirp. The modulation-independent grating section includes a diffraction grating for reflecting light and forms a laser cavity with the gain section for lasing at a wavelength or range of wavelengths reflected by the diffraction grating. The gain section of the semiconductor laser includes a gain electrode for driving the gain section with at least a modulated RF signal and the grating section includes a grating electrode for driving the grating section with a DC bias current independent of the modulation of the gain section. The semiconductor laser may thus be directly modulated with the modulated RF signal without the modulation significantly affecting the index of refraction in the diffraction grating, thereby reducing chirp.

Abstract: A semiconductor laser diode with integrated heating generally includes a lasing region and a heating region integrated into the same semiconductor structure or chip. The lasing region and the heating region include first and second portions, respectively, of the semiconductor layers forming the semiconductor structure and include first and second portions, respectively, of the active regions formed by the semiconductor layers. Separate laser and heater electrodes are electrically connected to the respective lasing and heating regions for driving the respective lasing and heating regions with drive currents. The heating region may thus be driven independently from the lasing region, and heat may be conducted through the semiconductor layers from the heating region to the lasing region allowing the temperature to be controlled more efficiently.

Abstract: A semiconductor laser diode with integrated heating generally includes a lasing region and a heating region integrated into the same semiconductor structure or chip. The lasing region and the heating region include first and second portions, respectively, of the semiconductor layers forming the semiconductor structure and include first and second portions, respectively, of the active regions formed by the semiconductor layers. Separate laser and heater electrodes are electrically connected to the respective lasing and heating regions for driving the respective lasing and heating regions with drive currents. The heating region may thus be driven independently from the lasing region, and heat may be conducted through the semiconductor layers from the heating region to the lasing region allowing the temperature to be controlled more efficiently.

Abstract: Individual channels of a multiplexed laser array in a multi-channel optical transmitter are monitored at an output of an optical multiplexer. The monitoring may be used to confirm proper operation of each of the channels in the multiplexed laser array and/or to perform wavelength locking on each of the channels. Monitoring at the output of the optical multiplexer avoids the use of multiple photodetectors coupled directly to multiple lasers in the multiplexed laser array. The multiplexed laser array generally includes a plurality of laser emitters optically coupled to an optical multiplexer such as an arrayed waveguide grating (AWG). An optical transmitter with a monitored multiplexed laser array may be used, for example, in an optical line terminal (OLT) in a wavelength division multiplexed (WDM) passive optical network (PON) or in any other type of WDM optical communication system capable of transmitting optical signals on multiple channel wavelengths.

Abstract: An optical transceiver generally includes an injection locked (IL) laser configured to generate a transmit (Tx) optical signal for transmission over an optical network and a laser driver circuit configured to modulate the IL laser based on a Tx data signal. The Tx data signal may be provided to the optical transceiver for transmission over the optical network. The Tx data signal may include a crossing point level associated with a transition between a first signal level and a second signal level. The optical transceiver may also include a crossing point control circuit configured to apply distortion to the Tx data signal, the distortion to increase the crossing point level.

Abstract: An optical transceiver generally includes an injection locked (IL) laser configured to generate a transmit (Tx) optical signal for transmission over an optical network and a laser driver circuit configured to modulate the IL laser based on a Tx data signal. The Tx data signal may be provided to the optical transceiver for transmission over the optical network. The Tx data signal may include a crossing point level associated with a transition between a first signal level and a second signal level. The optical transceiver may also include a crossing point control circuit configured to apply distortion to the Tx data signal, the distortion to increase the crossing point level.

Abstract: A tunable laser with multiple in-line sections generally includes a semiconductor laser body with a plurality of in-line laser sections each configured to be driven independently to generate laser light at a wavelength within a different respective wavelength range. The wavelength of the light generated in each of the laser sections may be tuned, in response to a temperature change, to a channel wavelength within the respective wavelength range. The laser light generated in each selected one of the laser sections is emitted from a front facet of the laser body. By selectively generating light in one or more of the laser sections, one or more channel wavelengths may be selected for lasing and transmission. The tunable laser with multiple in-line sections may be used, for example, in a tunable transmitter in an optical networking unit (ONU) in a WDM passive optical network (PON) to select a transmission channel wavelength.

Abstract: A tunable laser with multiple in-line sections including sampled gratings generally includes a semiconductor laser body with a plurality of in-line laser sections configured to be driven independently to generate laser light at a wavelength within a different respective wavelength range. Sampled gratings in the respective in-line sections have the same grating period and a different sampling period to produce the different wavelengths. The wavelength of the light generated in the respective laser sections may be tuned, in response to a temperature change, to a channel wavelength within the respective wavelength range. By selectively generating light in one or more of the laser sections, one or more channel wavelengths may be selected for lasing and transmission. By using sampled gratings with the same grating period in the multiple in-line sections, the multiple section tunable laser may be fabricated more easily.