Abstract: Electro-absorption modulators (EAM) and monolithically integrated electro-absorption modulated lasers (EML) and methods of fabrication are disclosed. Vertically stacked waveguides for a distributed feedback (DFB) laser, an electro-absorption modulator (EAM) and a passive output waveguide are vertically integrated, and the DFB laser, EAM and output waveguide are optically coupled using laterally tapered vertical optical couplers. Laterally tapered vertical optical couplers provides an alternative to conventional butt-coupling of a laser and EAM, offering improved reliability for high power operation over extended lifetimes. Optionally, the EML comprises monolithically integrated electronic circuitry, e.g., driver and control electronics for the DFB laser and EAM. Beneficially, integrated EAM driver and control circuitry comprises a high-speed electro-optical control loop for very high-speed linearization and temperature compensation, e.g.

Abstract: An optical receiver comprises a monolithically integrated photodiode (PD) and transimpedance amplifier (TIA). The TIA comprises InP heterojunction bipolar transistors (HBT) fabricated from a first plurality of layers of an epitaxial layer stack grown on a SI:InP substrate; the PD may be a pin PD fabricated from a second plurality of layers of the epitaxial layer stack, overlying the first plurality of layers. The p-contact of the PIN is directly connected to the input of the TIA to reduce PIN capacitance CPIN. The TIA capacitance CTIA may be matched to CPIN. The PD may be a vertical PIN with a top facet window or a waveguide PD with a lateral facet window. Device parameters comprising a device area, device capacitance CPIN+CTIA; and feedback resistance RF of the TIA are optimized to performance specifications comprising a specified sensitivity and responsivity at an operational wavelength. This design approach enables cost-effective fabrication of integrated PIN-TIA.

Abstract: Electro-photonic integrated circuits comprising optical transmitters and receivers are disclosed, wherein a monolithically integrated electro-absorption modulated laser (EML) is operable bidirectionally, in a transmitter mode and in a receiver mode. Vertically stacked waveguides are provided for a laser and an electro-absorption modulator (EAM). The laser and EAM are optically coupled using a laterally tapered vertical optical coupler. The EML comprises monolithically integrated electronic circuitry, e.g., driver and control electronics for the driving the laser and EAM as an EML, in transmitter mode. The electronic circuitry comprises a transimpedance amplifier (TIA). The EAM has first and second parts that can be 10 independently biased. In receiver mode, the laser current is reduced to close to the threshold, and a first part of the EAM is biased to absorb residual laser light, and the second part of the EAM acts as a photodiode receiver to provide a photocurrent to the TIA.

Abstract: An optical receiver comprises a variable optical attenuator (VOA), a photodiode (PD) which may be a pin-PD or an APD, a transimpedance amplifier (TIA), and a feedback/control circuit for adjusting a bias voltage of the VOA in response to an optical input signal level, to provide an attenuated optical output signal to the PD having a narrower dynamic range. Providing signal level adjustment in the optical domain mitigates the requirement for a TIA with a large dynamic range and provides for fast switching. The optical receiver may comprise a waveguide configuration, wherein a first electro-absorption modulator (EAM) is operable as the VOA and a second EAM is operable as the photodiode. A monolithically integrated electro-photonic circuit comprising the VOA, PD, TIA and feedback/control circuit may be provided using InP-based semiconductor materials.

Abstract: An optical receiver comprises a monolithically integrated pin photodiode (PIN) and transimpedance amplifier (TIA). The TIA comprises InP heterojunction bipolar transistors (HBT) fabricated from a first plurality of layers of an epitaxial layer stack grown on a SI:InP substrate; the PIN is fabricated from a second plurality of layers of the epitaxial layer stack. The p-contact of the PIN is directly connected to the input of the TIA to reduce PIN capacitance CPIN. The TIA capacitance CTIA may be matched to CPIN. Device parameters comprising: a thickness of the absorption layer, window area, and an optional mirror thickness of the PIN; device capacitance CPIN+CTIA; and feedback resistance RF of the TIA; are optimized to performance specifications comprising a specified sensitivity and responsivity at an operational wavelength. This design approach enables cost-effective fabrication an integrated PIN-TIA, for applications such as a 1577 nm receiver for an ONU for 10G-PON.

Abstract: A burst-mode optical receiver for an optical line terminal (OLT) of a passive optical network (PON) comprises a variable optical attenuator (VOA), a photodiode (PD) which may be a pin-PD or an APD, a transimpedance amplifier (TIA), and a feedback/control circuit for adjusting a bias voltage of the VOA in response to a burst-mode optical input signal level, to provide an attenuated optical output signal to the PD having a narrower dynamic range. Providing signal level adjustment in the optical domain mitigates the requirement for a burst-mode TIA with a large dynamic range and provides for fast switching. The burst-mode optical receiver may comprise a waveguide configuration, wherein a first electro-absorption modulator (EAM) is operable as the VOA and a second EAM is operable as the photodiode. A monolithically integrated electro-photonic circuit comprising the VOA, PD, TIA and feedback/control circuit may be provided using InP-based semiconductor materials.

Abstract: Electro-photonic integrated circuits comprising optical transmitters and receivers are disclosed, wherein a monolithically integrated electro-absorption modulated laser (EML) is operable bidirectionally, in a transmitter mode and in a receiver mode. Vertically stacked waveguides are provided for a laser and an electro-absorption modulator (EAM). The laser and EAM are optically coupled using a laterally tapered vertical optical coupler. The EML comprises monolithically integrated electronic circuitry, e.g., driver and control electronics for the driving the laser and EAM as an EML, in transmitter mode. The electronic circuitry comprises a transimpedance amplifier (TIA). The EAM has first and second parts that can be independently biased. In receiver mode, the laser current is reduced to close to the threshold, and a first part of the EAM is biased to absorb residual laser light, and the second part of the EAM acts as a photodiode receiver to provide a photocurrent to the TIA.

Abstract: Electro-photonic integrated circuits comprising optical transmitters and receivers are disclosed, wherein a monolithically integrated electro-absorption modulated laser (EML) is operable bidirectionally, in a transmitter mode and in a receiver mode. Vertically stacked waveguides are provided for a laser and an electro-absorption modulator (EAM). The laser and EAM are optically coupled using a laterally tapered vertical optical coupler. The EML comprises monolithically integrated electronic circuitry, e.g., driver and control electronics for the driving the laser and EAM as an EML, in transmitter mode. The control circuitry comprises a transimpedance amplifier (TIA). The EAM has first and second parts that can be independently biased. In receiver mode, the laser current is reduced to close to the threshold, and a first part of the EAM is biased to absorb residual laser light, and the second part of the EAM acts as a photodiode receiver to provide a photocurrent to the TIA.

Abstract: A burst-mode optical receiver for an optical line terminal (OLT) of a passive optical network (PON) comprises a variable optical attenuator (VOA), a photodiode (PD) which may be a pin-PD or an APD, a transimpedance amplifier (TIA), and a feedback/control circuit for adjusting a bias voltage of the VOA in response to a burst-mode optical input signal level, to provide an attenuated optical output signal to the PD having a narrower dynamic range. Providing signal level adjustment in the optical domain mitigates the requirement for a burst-mode TIA with a large dynamic range and provides for fast switching. The burst-mode optical receiver may comprise a waveguide configuration, wherein a first electro-absorption modulator (EAM) is operable as the VOA and a second EAM is operable as the photodiode. A monolithically integrated electro-photonic circuit comprising the VOA, PD, TIA and feedback/control circuit may be provided using InP-based semiconductor materials.

Abstract: An optical receiver comprises a monolithically integrated pin photodiode (PIN) and transimpedance amplifier (TIA). The TIA comprises InP heterojunction bipolar transistors (HBT) fabricated from a first plurality of layers of an epitaxial layer stack grown on a SI:InP substrate; the PIN is fabricated from a second plurality of layers of the epitaxial layer stack. The p-contact of the PIN is directly connected to the input of the TIA to reduce PIN capacitance CPIN. The TIA capacitance CTIA may be matched to CPIN. Device parameters comprising: a thickness of the absorption layer, window area, and an optional mirror thickness of the PIN; device capacitance CPIN+CTIA; and feedback resistance RF of the TIA; are optimized to performance specifications comprising a specified sensitivity and responsivity at an operational wavelength. This design approach enables cost-effective fabrication an integrated PIN-TIA, for applications such as a 1577 nm receiver for an ONU for 10G-PON.

Abstract: Semiconductor device structures comprising laser diode cavities with at least one of a mode-selective filter and a phase-alignment element, and methods for their fabrication, are disclosed. An example device structure comprises a surface-etched grating distributed-feedback (SEG DFB) laser with a mode-selective reflector structure. The reflector structure is designed to provide higher pot feedback of the fundamental TE0 mode and suppression of higher order mode effects. The reflector structure may be a single interface (single facet) mirror type reflector comprising a spatially patterned reflector, or a multi-interface distributed Bragg reflector (DBR). A phase alignment element may be included to provide precise optical phase control. A photodetector for back-facet power monitoring may be included. A method of fabrication is disclosed, based on a self-aligned process in which DBR features are included on the same mask that is used for the DFB laser grating.