Abstract: In this invention, a semiconductor device designed for use as an optical amplifier is provided with three sections; an input section, a middle section and an output section. A continuous optical waveguide extends through the input section, the middle section and the output section and the three sections are electrically isolated from each other. More specifically, a semiconductor laser amplifier is electrically split into three separate sections by implanting ions of, for example, hydrogen, helium or fluorine into the areas of the semiconductor amplifier which are between the middle section and the two end sections. The ion implantation provides a high degree of electrical isolation between the various sections, but it does not alter the continuity of the optical waveguide which passes through the three sections.

Abstract: An improved process for fabricating photonic circuits is disclosed. The inventive process starts with a growth of a base wafer comprising a stack of epitaxial layers of various materials. At least a portion of each of the material layers will ultimately be a functioning part of any of a number of devices which will form the PIC or will serve a role in at least one of the fabrication processing steps. Specific inventive processing steps are addressed to (1) interconnecting passive waveguides, active devices, and grating filtering regions without the substantial optical discontinuities which appear in the prior art, and (2) etching continuous waveguide mesas to different depths in different regions of the PIC so as to optimize the performance of each PIC device.

Abstract: Various optical functions are generated in accordance with the present invention of a novel broadly tunable monolithic wavelength selective coupler which can be integrated with a gain medium to form a broadly tunable laser. The tunable wavelength selective coupler supports a pair of asynchronous waveguides, an upper waveguide and a lower waveguide, in combination with a phase match course grating for coupling optical energy between said waveguides. One end of the lower waveguide terminates at an output facet. The corresponding end of the upper waveguide terminates in an optical signal absorbing medium. The other end of the lower waveguide is terminated to prevent optical energy from entering the waveguide; and, the corresponding end of the upper waveguide terminates at an input facet.

Abstract: An improved process for fabricating photonic circuits is disclosed. The inventive process starts with a growth of a base wafer comprising a stack of epitaxial layers of various materials. At least a portion of each of the material layers will ultimately be a functioning part of any of a number of devices which will form the PIC or will serve a role in at least one of the fabrication processing steps. Specific inventive processing steps are addressed to (1) interconnecting passive waveguides, active devices, and grating filtering regions without the substantial optical discontinuities which appear in the prior art, and (2) etching continuous waveguide mesas to different depths in different regions of the PIC so as to optimize the performance of each PIC device.

Abstract: Full duplex lightwave communications is achieved in a diplex transceiver realized in a semiconductor photonic integrated circuit having an inline interconnecting waveguide integral with the transmitting and receiving portions of the transceiver. Semiconductor lasers and detectors operating in different wavelength regimes permit diplex or wavelength-division-multiplexed operation. In the transceiver, lightwave signals from the laser propagate through the detector without interfering with the detector operation or the lightwave signals being detected.

Abstract: An optical amplifier and photodetector are monolithically integrated, with the photodetector being optically coupled to the optical amplifier through a low radiative loss and low back reflectivity branching waveguide. Because of the low reflectivity, the branching waveguide, although having a truncated wedge tip, is able to redirect a small portion of optical radiation from the amplifier to the photodetector without deleteriously effecting the performance of the optical amplifier. The branching waveguide is realized by employing between the branches of the waveguide, a junction region having a gradual decrease in effective refractive index such as to decrease the difference between the refractive indices at the optical interface of the truncated wedge tip as seen by optical radiation incident thereto from the optical amplifier.

Abstract: An optical branching waveguide having low radiative loss and low back-reflectivity is described. By employing between the branches a region having a gradual decrease in effective refractive index along the direction of optical propagation, the deleterious effect of wedge tip truncation can be reduced. According to the teachings of the invention, this may be accomplished by gradually decreasing the thickness of the optical material along the axis of optical propagation and planarizing the region with an optical material having a lower refractive index than the underlying optical material.

Abstract: Full duplex lightwave communications is achieved in a diplex transceiver realized in a semiconductor photonic integrated circuit having an inline interconnecting waveguide integral with the transmitting and receiving portions of the transceiver. Semiconductor lasers and detectors operating in different wavelength regimes permit diplex or wavelength-division-multiplexed operation. In the transceiver, lightwave signals from the laser propagate through the laser without interfering with the laser operation or the lightwave signals being generated.

Abstract: Wavelength tunability and single frequency output are achieved in a coherent light source employing an adjustably controllable reflector. The light source includes a gain medium coupled to a single-mode fiber having a partially reduced cladding region at a predetermined distance from the gain medium. A Bragg reflector is either formed on the reduced cladding region of the single-mode fiber or formed on an external element in close proximity to the reduced cladding region. A single resonant optical cavity is formed by placing another reflector on the side of the gain medium opposite the gain medium-to-fiber coupling. Wavelength tuning of the light source is accomplished by controllably adjusting the period or the Bragg reflector element.

Abstract: Adiabatic mode control and structural reproducibility are achieved by a tapered semiconductor waveguide structure wherein semiconductor guiding layers are interleaved with stop-etch layers and each guiding layer extends further along the propagation axis of the waveguide further than the guiding layer immediately adjacent thereabove to create a staircase-like core or guiding structure. Cladding regions of appropriate semiconductor material having a lower index of refraction than the tapered core structure may be added to completely surround the tapered guiding structure. The profile of the tapered structure is realizable as any desired staircase-like shape such as linear, parabolic, exponential or the like. Additional layers of higher index of refraction semiconductor material may be included in the cladding region to permit additional beam shaping of the expanded spatial mode propagating along the tapered waveguide.

Abstract: Adiabatic mode control and structural reproducibility are achieved by a tapered semiconductor waveguide structure wherein semiconductor guiding layers are interleaved with stop-etch layers and each successive guiding layer extends further along the propagation axis of the waveguide than the guiding layer immediately adjacent thereabove to create a staircase-like core or guiding structure. Cladding regions of appropriate semiconductor material having a lower index of refraction than the tapered core structure may be added to completely surround the tapered guiding structure. The profile of the tapered structure is realizable as any desired staircase-like shape such as linear, parabolic, exponential or the like. Additional layers of higher index of refraction semiconductor material may be included in the cladding region to permit additional beam shaping of the expanded spatial mode propagating along the tapered waveguide.

Abstract: A grating coupler is combined with a quantum well index modulator and an optical waveguide to alter the reverse or forward coupling characteristics between two different propagation modes of the system.