Optoelectronic oscillator and pulse generator

• US 8,031,012 B2
• Filed: 02/06/2009
• Issued: 10/04/2011
• Est. Priority Date: 02/08/2008
• Status: Expired due to Fees

• Current Assignee: Furukawa Electric Company Limited
• Original Assignee: Furukawa Electric Company Limited
• Inventors: Hasegawa, Hideaki
• Primary Examiner(s): Gannon; Levi
• Application Number:
  US12/367,086
• Publication Number:
  US 20090225799A1
• Time in Patent Office: 970 Days
• Field of Search: 331/66, 250/205, 250/227.11, 250/227.12, 359237-239, 359/245, 359/246, 372/6, 372/25, 372/26, 372/29.011, 372/29.014, 372/29.02, 372 30- 32, 372/38.01, 372/38.02, 372/38.07, 385 1- 3, 385/8, 385/39
• US Class Current: 331/66
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 2006/12121 Laser
• CPC Class Codes: G02B 2006/12123 Diode
• CPC Class Codes: G02B 2006/1213 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/1223 high refractive index type, i.e. high-contrast waveguides
• CPC Class Codes: G06F 1/04 Generating or distributing clock signals or signals derived directly therefrom
• CPC Class Codes: H01S 5/06223 using delayed or positive feedback

Abstract

The objects of the present invention are to shorten a cavity length of an optoelectronic oscillator and to integrate on a semiconductor or SiO2-substrate. An optoelectronic oscillator 10 have an optoelectronic loop comprising a semiconductor laser 11, an optical waveguide 12 guiding laser light emitted from the semiconductor laser, a photodetector 13 detecting laser light guided by the optical waveguide and outputting an electrical signal, an amplifier 14 amplifying the electrical signal outputted from the photodetector, generating an amplified signal and formed on a semiconductor substrate 15. Laser light emitted from the semiconductor laser 11 is controlled by generated amplified signal and it oscillates with a fundamental oscillation frequency determined by a delay time of carrier in the optoelectronic loop circuit or one of the high harmonic components of integral multiples of a fundamental oscillation frequency.

Claims

1. An optoelectronic oscillator having an optoelectronic loop circuit, said optoelectronic loop circuit formed on a semiconductor substrate or a SiO2 substrate, said optoelectronic loop circuit comprising:

a semiconductor laser;

an optical waveguide guiding laser light emitted from said semiconductor laser, wherein said optical waveguide has a length on an order of centimeters;

a photodetector detecting said laser light guided by said optical waveguide and outputting an electrical signal;

an amplifier amplifying said electrical signal outputted from said photodetector and generating an amplified signal; and

a refractive index compensation part, made of silicone resin, that compensates a change of a refractive index by a temperature of said optical waveguide, wherein said refractive index compensation part has a length shorter than the length of said optical waveguide and is formed in the middle of said optical waveguide,

wherein said optoelectronic oscillator modulates said laser light emitted from said semiconductor laser by said amplified signal, and said optoelectronic oscillator generates microwave and optical pulses with a fundamental oscillation frequency determined by a delay time of said microwave and optical pulses at said optoelectronic loop circuit or a high harmonic component of integral multiples of said fundamental oscillation frequency.

2. An optoelectronic oscillator according to claim 1, wherein said optical waveguide includes a clad comprising a silicon oxide film formed on a silicon substrate and a core doped with impurity and formed in said silicon oxide film.

3. An optoelectronic oscillator according to claim 2, wherein said amplifier includes a CMOS (Complementary Metal Oxide Semiconductor) transistor formed on said silicon substrate.

4. An optoelectronic oscillator according to claim 1, wherein said optical waveguide comprises compound semiconductor or SiO2 formed on a compound semiconductor substrate.

5. An optoelectronic oscillator according to claim 3, wherein said compound semiconductor is InP or GaAs.

6. An optoelectronic oscillator according to claim 1, wherein said optical waveguide comprises compound semiconductor or SiO2 formed on a SiO2-substrate.

7. An optoelectronic oscillator according to claim 1, wherein said amplified signal directly modulates a drive current of said semiconductor laser.

8. An optoelectronic oscillator according to claim 1, wherein said optoelectronic loop circuit further comprises an optical modulator intercalated between said semiconductor laser and said optical waveguide, and said amplified signal modulates an emission light of said semiconductor laser through said optical modulator.

9. A pulse generator comprising an optoelectronic oscillator having an optoelectronic loop circuit, said optoelectronic loop circuit formed on a semiconductor substrate or a SiO2 substrate, said optoelectronic loop circuit comprising:

a semiconductor laser;

an optical waveguide guiding laser light emitted from said semiconductor laser, wherein said optical waveguide has a length on an order of centimeters;

a photodetector detecting said laser light guided by said optical waveguide and outputting an electrical signal;

an amplifier amplifying said electrical signal outputted from said photodetector and generating an amplified signal; and

a refractive index compensation part made of a silicone resin that compensates a change of a refractive index by a temperature of said optical waveguide, wherein said refractive index compensation part has a length shorter than the length of the optical waveguide and formed in the middle of said optical waveguide,

wherein said optoelectronic oscillator modulates said laser light emitted from said semiconductor laser by said amplified signal, and said optoelectronic oscillator generates microwave and optical pulses with a fundamental oscillation frequency determined by a delay time of said microwave and optical pulses at said optoelectronic loop circuit or a high harmonic component of integral multiples of said fundamental oscillation frequency.

10. The pulse generator of claim 9, wherein said optical waveguide comprises compound semiconductor or SiO2 formed on a SiO2-substrate.

11. The pulse generator of claim 9, wherein said refractive index compensation part includes a photonic crystal structure including a semiconductor material and said optoelectronic loop circuit further includes a filter.

12. A method, comprising:

forming an optoelectric loop circuit on a semiconductor substrate or a SiO2 substrate, wherein the optoelectric loop circuit comprises a semiconductor laser, an optical waveguide guiding laser light, wherein said optical waveguide has a length on an order of centimeters, a photodetector outputting an electrical signal in response to the laser light, an amplifier generating an amplified signal, and a refractive index compensation part made of a silicone resin that compensates a change of a refractive index by a temperature of said optical waveguide, wherein said refractive index compensation part has a length shorter than the length of the optical waveguide and formed in the middle of said optical waveguide;

modulating said laser light by said amplified signal; and

generating microwave and optical pulses with a fundamental oscillation frequency determined by a delay time of said microwave and optical pulses at said optoelectronic loop circuit or a high harmonic component of integral multiples of said fundamental oscillation frequency.

13. An optoelectronic oscillator having an optoelectronic loop circuit, said optoelectronic loop circuit formed on a semiconductor substrate or a SiO2 substrate, said optoelectronic loop circuit comprising:

a semiconductor laser;

an optical waveguide with a length on an order of centimeters, wherein the optical waveguide guiding laser light emitted from said semiconductor laser;

a photodetector detecting said laser light guided by said optical waveguide and outputting an electrical signal; and

an amplifier amplifying said electrical signal outputted from said photodetector and generating an amplified signal,

wherein said optoelectronic oscillator modulates said laser light emitted from said semiconductor laser by said amplified signal, and said optoelectronic oscillator generates microwave and optical pulses with a fundamental oscillation frequency determined by a delay time of said microwave and optical pulses at said optoelectronic loop circuit or a high harmonic component of integral multiples of said fundamental oscillation frequency,

wherein said optoelectronic loop circuit includes a refractive index compensation part compensating a change of a refractive index by a temperature of said optical waveguide,

wherein said refractive index compensation part includes silicone resin, is of a length shorter than said waveguide, and is formed in the middle of said waveguide.

14. An optoelectronic oscillator having an optoelectronic loop circuit, said optoelectronic loop circuit formed on a semiconductor substrate or a SiO2 substrate, said optoelectronic loop circuit comprising:

a semiconductor laser;

an optical waveguide having a core made of SiO₂ buried by the SiO₂, the optical waveguide guiding laser light emitted from said semiconductor laser;

a photodetector detecting said laser light guided by said optical waveguide and outputting an electrical signal; and

an amplifier amplifying said electrical signal outputted from said photodetector and generating an amplified signal,

wherein said optoelectronic oscillator modulates said laser light emitted from said semiconductor laser by said amplified signal, and said optoelectronic oscillator generates microwave and optical pulses with a fundamental oscillation frequency determined by a delay time of said microwave and optical pulses at said optoelectronic loop circuit or a high harmonic component of integral multiples of said fundamental oscillation frequency,

wherein a photonic crystal made of SiO₂ is provided at the middle of the optical waveguide, wherein the photonic crystal decreases a group velocity of the laser light propagating in the wave guide by extending a group refractive index,

wherein said optoelectronic loop circuit further includes a filter, and

wherein a normalized wave number, k/(2π

/a1), is 0.3 to 0.5, wherein k is a wave number of light guided in the optical waveguide and a1 is a hole interval of said photonic crystal structure in a parallel direction to the traveling direction of light.

15. An optoelectronic oscillator according to claim 14, wherein said photonic crystal structure of said optical waveguide has said group refractive index of more than 100 and is formed longer than 5 cm.

16. An optoelectronic oscillator according to claim 14, wherein said high harmonic components of integral multiples of said fundamental oscillation frequency are extracted by an electrical filter.

17. An optoelectronic oscillator according to claim 14, wherein said filter comprises an SG-DBR (Sampled Grating-Distributed Bragg Reflector) or a Fabry-Perot type optical filter.

18. An optoelectronic oscillator according to claim 14, wherein said filter comprises a bypass optical waveguide other than said waveguide, and said bypass optical waveguide connects an optical input port and an optical output port of said optical waveguide.