Patents by Inventor Ram Jambunathan
Ram Jambunathan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
-
Patent number: 6987908Abstract: A grating dispersion compensator (GDC), including: a substrate; a dielectric grating layer; a planar waveguide; and a passivation layer. The dielectric grating layer may be formed on the substrate and includes a variation in refractive index. This variation in refractive index defines a grating period. The grating period may vary along the longitudinal axis of the GDC according to a predetermined function. A selected center wavelength and dispersion curve may be created. The chirp of the grating period may be controlled by current, voltage, temperature, or pressure. The planar waveguide is formed on the dielectric grating layer and includes an input/output (I/O) surface normal to the longitudinal axis of the planar waveguide. The passivation layer is formed on the planar waveguide. Alternatively, a GDC may be formed with the dielectric grating layer on top of the planar waveguide rather then beneath it.Type: GrantFiled: June 11, 2002Date of Patent: January 17, 2006Assignee: T-Networks, Inc.Inventors: Aaron Bond, Ram Jambunathan, Newton C. Frateschi
-
Patent number: 6862376Abstract: A method of manufacturing a monolithic expanded beam mode electroabsorption modulator including a waveguide layer with a two expansion/contraction sections and an electroabsorption section arranged along a longitudinal axis. At least one patterned growth retarding layer is formed on the top surface of a substrate. The waveguide layer is formed on a portion of the top surface of the substrate by selective area growth and has an index of refraction different from the substrate. An electroabsorption portion of the waveguide layer has a thickness which is greater than thicknesses in its other portions. The semiconductor layer is formed on the waveguide layer and includes an index of refraction different from the waveguide. The waveguide and semiconductor layers are defined and etched to form the expansion/contraction and electroabsorption sections of the waveguide layer. Electrical contacts are formed, one electrically coupled to the substrate and another electrically coupled to the semiconductor layer.Type: GrantFiled: July 21, 2004Date of Patent: March 1, 2005Assignee: T-Networks, Inc.Inventors: Aaron Bond, Ram Jambunathan, Won Jin Choi
-
Patent number: 6844212Abstract: A grating dispersion compensator (GDC), including: a substrate; a dielectric grating layer; a planar waveguide; and a passivation layer; is disclosed. The dielectric grating layer may be formed on the substrate and includes a variation in refractive index. This variation in refractive index defines a grating period. The grating period may vary along the longitudinal axis of the GDC according to a predetermined function. A selected center wavelength and dispersion curve may be created. The chirp of the grating period may be controlled by current, voltage, temperature, or pressure. The planar waveguide is formed on the dielectric grating layer and includes an input/output (I/O) surface normal to the longitudinal axis of the planar waveguide. The passivation layer is formed on the planar waveguide. Alternatively, a GDC may be formed with the dielectric grating layer on top of the planar waveguide rather than beneath it.Type: GrantFiled: May 12, 2004Date of Patent: January 18, 2005Assignee: T-Networks, Inc.Inventors: Aaron Bond, Ram Jambunathan, Newton C. Frateschi
-
Patent number: 6844954Abstract: An exemplary monolithic stabilized monolithic transmissive active optical device, such as an electroabsorption modulator (EAM), a variable optical attenuator (VOA), or a semiconductor optical amplifier (SOA), with an output optical tap, is formed from: a substrate; a waveguide layer; a semiconductor layer. The waveguide layer is coupled to the substrate and includes an active medium, which interacts with a predetermined wavelength of light, and is responsive to an electric signal. The electric signal is applied between the substrate and the semiconductor layer. The waveguide layer includes an output optical tap section and an active section adjacent to the output optical tap section. These sections include portions of the active medium. Further embodiments of the present invention incorporate temperature as well as bias control to improve performance of exemplary monolithic transmissive active optical devices.Type: GrantFiled: August 6, 2003Date of Patent: January 18, 2005Assignee: T-Networks, Inc.Inventors: Aaron Bond, John Kai Anderson, Ram Jambunathan
-
Publication number: 20040258339Abstract: A method of manufacturing a monolithic expanded beam mode electroabsorption modulator including a waveguide layer with a two expansion/contraction sections and an electroabsorption section arranged along a longitudinal axis. At least one patterned growth retarding layer is formed on the top surface of a substrate. The waveguide layer is formed on a portion of the top surface of the substrate by selective area growth and has an index of refraction different from the substrate. An electroabsorption portion of the waveguide layer has a thickness which is greater than thicknesses in its other portions. The semiconductor layer is formed on the waveguide layer and includes an index of refraction different from the waveguide. The waveguide and semiconductor layers are defined and etched to form the expansion/contraction and electroabsorption sections of the waveguide layer. Electrical contacts are formed, one electrically coupled to the substrate and another electrically coupled to the semiconductor layer.Type: ApplicationFiled: July 21, 2004Publication date: December 23, 2004Inventors: Aaron Bond, Ram Jambunathan, Won Jin Choi
-
Patent number: 6828166Abstract: A low threshold distributed feedback (DFB) laser is constructed for improved performance at subzero temperatures. A loss grating is employed to enhance the probability that lasing occurs near the short wavelength side of the stopband and to counteract the effect of negative gain tilt that occurs when DFB lasers are positively detuned. A method of making DFB lasers from wafers with improved yield for low temperature side mode suppression ratio (SMSR) is also disclosed.Type: GrantFiled: September 6, 2002Date of Patent: December 7, 2004Assignee: Agere Systems, Inc.Inventors: Lars E. Eng, Ram Jambunathan, Kishore K. Kamath, Alexander Robertson, Daniel Paul Wilt
-
Publication number: 20040208446Abstract: A grating dispersion compensator (GDC), including: a substrate; a dielectric grating layer; a planar waveguide; and a passivation layer; is disclosed. The dielectric grating layer may be formed on the substrate and includes a variation in refractive index. This variation in refractive index defines a grating period. The grating period may vary along the longitudinal axis of the GDC according to a predetermined function. A selected center wavelength and dispersion curve may be created. The chirp of the grating period may be controlled by current, voltage, temperature, or pressure. The planar waveguide is formed on the dielectric grating layer and includes an input/output (I/O) surface normal to the longitudinal axis of the planar waveguide. The passivation layer is formed on the planar waveguide. Alternatively, a GDC may be formed with the dielectric grating layer on top of the planar waveguide rather than beneath it.Type: ApplicationFiled: May 12, 2004Publication date: October 21, 2004Inventors: Aaron Bond, Ram Jambunathan, Newton C. Frateschi
-
Patent number: 6804421Abstract: A monolithic single pass expanded beam mode active optical device includes: a substrate; a waveguide layer coupled to the top surface of the substrate; a semiconductor layer coupled to the waveguide layer; first and second electrodes for receiving an electric signal coupled to the substrate and the semiconductor layer, respectively. The waveguide layer includes a plurality of sublayers, forming a quantum well structure, which is responsive to the electric signal. The waveguide layer has three sections, two expansion/contraction sections and an active section, which extends between and adjacent to the two expansion/contraction sections. The thickness of at least one of the plurality of sublayers varies within the expansion/contraction portions of the quantum well structure. Possible interactions of the active region with the light include: absorption in the case of an electro-absorptive modulator and optical gain.Type: GrantFiled: January 25, 2002Date of Patent: October 12, 2004Assignee: T-Networks, Inc.Inventors: Aaron Bond, Ram Jambunathan, Won Jin Choi
-
Publication number: 20040027634Abstract: An exemplary monolithic stabilized monolithic transmissive active optical device, such as an electroabsorption modulator (EAM), a variable optical attenuator (VOA), or a semiconductor optical amplifier (SOA), with an output optical tap, is formed from: a substrate; a waveguide layer; a semiconductor layer. The waveguide layer is coupled to the substrate and includes an active medium, which interacts with a predetermined wavelength of light, and is responsive to an electric signal. The electric signal is applied between the substrate and the semiconductor layer. The waveguide layer includes an output optical tap section and an active section adjacent to the output optical tap section. These sections include portions of the active medium. Further embodiments of the present invention incorporate temperature as well as bias control to improve performance of exemplary monolithic transmissive active optical devices.Type: ApplicationFiled: August 6, 2003Publication date: February 12, 2004Inventors: Aaron Bond, John Kai Andersen, Ram Jambunathan
-
Patent number: 6661556Abstract: An exemplary monolithic stabilized monolithic transmissive active optical device, such as an electroabsorption modulator (EAM), a variable optical attenuator (VOA), or a semiconductor optical amplifier (SOA), with an output optical tap, includes: a substrate; a waveguide layer; a semiconductor layer. The waveguide layer is coupled to the substrate and includes an active medium, which interacts with a predetermined wavelength of light, and is responsive to an electric signal. The electric signal is applied between the substrate and the semiconductor layer. The waveguide layer includes an output optical tap section and an active section adjacent to the output optical tap section. These sections include portions of the active medium. Further embodiments of the present invention incorporate temperature as well as bias control to improve performance of exemplary monolithic transmissive active optical devices. Additional embodiments include exemplary methods of manufacture and methods of operation.Type: GrantFiled: August 14, 2002Date of Patent: December 9, 2003Assignee: T-Networks, Inc.Inventors: Aaron Bond, John Kai Andersen, Ram Jambunathan
-
Publication number: 20030142895Abstract: A monolithic single pass expanded beam mode active optical device includes: a substrate; a waveguide layer coupled to the top surface of the substrate; a semiconductor layer coupled to the waveguide layer; first and second electrodes for receiving an electric signal coupled to the substrate and the semiconductor layer, respectively. The waveguide layer includes a plurality of sublayers, forming a quantum well structure, which is responsive to the electric signal. The waveguide layer has three sections, two expansion/contraction sections and an active section, which extends between and adjacent to the two expansion/contraction sections. The thickness of at least one of the plurality of sublayers varies within the expansion/contraction portions of the quantum well structure. Possible interactions of the active region with the light include: absorption in the case of an electro-absorptive modulator and optical gain.Type: ApplicationFiled: January 25, 2002Publication date: July 31, 2003Inventors: Aaron Bond, Ram Jambunathan, Won Jin Choi
-
Publication number: 20030043448Abstract: An exemplary monolithic stabilized monolithic transmissive active optical device, such as an electroabsorption modulator (EAM), a variable optical attenuator (VOA), or a semiconductor optical amplifier (SOA), with an output optical tap, includes: a substrate; a waveguide layer; a semiconductor layer. The waveguide layer is coupled to the substrate and includes an active medium, which interacts with a predetermined wavelength of light, and is responsive to an electric signal. The electric signal is applied between the substrate and the semiconductor layer. The waveguide layer includes an output optical tap section and an active section adjacent to the output optical tap section. These sections include portions of the active medium. Further embodiments of the present invention incorporate temperature as well as bias control to improve performance of exemplary monolithic transmissive active optical devices. Additional embodiments include exemplary methods of manufacture and methods of operation.Type: ApplicationFiled: August 14, 2002Publication date: March 6, 2003Inventors: Aaron Bond, John Kai Andersen, Ram Jambunathan
-
Publication number: 20030039442Abstract: A grating dispersion compensator (GDC), including: a substrate; a dielectric grating layer; a planar waveguide; and a passivation layer; is disclosed. The dielectric grating layer may be formed on the substrate and includes a variation in refractive index. This variation in refractive index defines a grating period. The grating period may vary along the longitudinal axis of the GDC according to a predetermined function. A selected center wavelength and dispersion curve may be created. The chirp of the grating period may be controlled by current, voltage, temperature, or pressure. The planar waveguide is formed on the dielectric grating layer and includes an input/output (I/O) surface normal to the longitudinal axis of the planar waveguide. The passivation layer is formed on the planar waveguide. Alternatively, a GDC may be formed with the dielectric grating layer on top of the planar waveguide rather than beneath it.Type: ApplicationFiled: June 11, 2002Publication date: February 27, 2003Inventors: Aaron Bond, Ram Jambunathan, Newton C. Fratesch
-
Publication number: 20030002557Abstract: A low threshold distributed feedback (DFB) laser is constructed for improved performance at subzero temperatures. A loss grating is employed to enhance the probability that lasing occurs near the short wavelength side of the stopband and to counteract the effect of negative gain tilt that occurs when DFB lasers are positively detuned. A method of making DFB lasers from wafers with improved yield for low temperature side mode suppression ratio (SMSR) is also disclosed.Type: ApplicationFiled: September 6, 2002Publication date: January 2, 2003Inventors: Lars E. Eng, Ram Jambunathan, Kishore K. Kamath, Alexander Robertson, Daniel Paul Wilt
-
Patent number: 6477194Abstract: A low threshold distributed feedback (DFB) laser is constructed for improved performance at subzero temperatures. A loss grating is employed to enhance the probability that lasing occurs near the short wavelength side of the stopband and to counteract the effect of negative gain tilt that occurs when DFB lasers are positively detuned. A method of making DFB lasers from wafers with improved yield for low temperature side mode suppression ratio (SMSR) is also disclosed.Type: GrantFiled: November 15, 1999Date of Patent: November 5, 2002Assignee: Agere Systems Guardian Corp.Inventors: Lars E. Eng, Ram Jambunathan, Kishore K. Kamath, Alexander Robertson, Daniel Paul Wilt