Optical modulator having Mach-Zender arrangement and method to generate modulated optical signal using the same
AssigneeSumitomo Electric Industries, Ltd.
InventorMichio Murata
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Abstract
A semiconductor optical modulator with the Mach-Zender type is disclosed. The optical modulator of the invention cab driven by a single phase signal and reduce the chirping of the modulated light. Two waveguides of the Mach-Zender modulator each including an active layer showing the exciton resonance in the refractive index are connected with a resistor. The driving signal is applied to one of the waveguides, while, the signal is applied to the other waveguide through the resistor where the other waveguide is grounded through a resistor. Adjusting the resistance of two resistors and the amplitude of the applied signal, the Mach-Zender modulator shows a substantial modulation degree with substantially no chirping characteristic.
Claims12
A semiconductor optical modulator with a Mach-Zender type having a semiconductor substrate, an optical de-coupler, an optical coupler, and first and second waveguides each provided on said semiconductor substrate and optically coupled with said optical de-coupler and said optical coupler, said optical modulator further comprising:
- a first resistor connecting said first waveguide and said second waveguide;
- and
- a second resistor for grounding said second waveguide, wherein said first and second resistors are connected in series,
- wherein said first waveguide is provided with a driving signal superposed with a first bias voltage, and said second waveguide is biased by a second bias voltage generated by a resistive divider constituted of said first and second resistors.
A method to generate a modulated light by a semiconductor optical modulator with a Mach-Zender type having an optical de-coupler, an optical coupler, and first and second waveguides each connected to said optical de-coupler in an end and connected to said optical coupler in another end, said method comprising steps of:
- generating first and second light each de-coupled by said optical de-coupler from incident light, said first light being provided to said first waveguide and said second light being provided to said second waveguide;
- applying a first bias voltage to said first waveguide to generate third light and a second bias voltage different from said first bias voltage to said second waveguide to generate fourth light;
- generating output light by coupling said third light with said fourth light by said optical coupler,
- wherein said second bias voltage is generated from said first bias voltage by a resistive divider constituted of a first resistor connecting said first waveguide to said second waveguide and a second resistor grounding said second waveguide.
Dependencies are inferred from the claim text.