Light pulse intensity regenerator, light tranforming repeater, pre-amplifier for light signal, light intensity change measuring apparatus, and stabilized light source

• US 5,350,913 A
• Filed: 04/23/1993
• Issued: 09/27/1994
• Est. Priority Date: 04/24/1992
• Status: Expired due to Fees

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Aoshima, Shinichiro, Hirano, Isuke
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US08/051,688
• Time in Patent Office: 522 Days
• Field of Search: 250/214 VT, 250/201.1, 250/214 A, 250/201.9, 250/205, 359/174-179
• US Class Current: 250/205
• CPC Class Codes: H04B 10/299 Signal waveform processing, e.g. reshaping or retiming

Abstract

Input light incident into fiber end is separated by a light separator. Light traveling straight through the light separator is guided through an optical fiber to a light amplifying and deflecting section, where only components with deflection angle in a predetermined range are amplified and deflected then to be extracted. The extracted components are output as output light through an optical fiber. The other part of light separated by the light separator is received by a photo detector. The light received by the photo detector is converted into an electric signal, and the electric signal is then input into the light amplifying and deflecting section. Using the electric signal generated from the photo detector, desired wave shaping may be effected by adjusting a light amplification factor of the light amplifying and deflecting section, a change speed of deflection angle, and/or a range of deflection angle selected.

Claims

1. A light pulse intensity regenerating apparatus comprising:

separating means for separating incident light into a first beam and a second beam;

light detecting means for receiving said first beam from said separating means;

a light amplifying section for amplifying the second beam from said separating means in accordance with an amplitude of an electric signal output from said light detecting means;

a light deflecting section for deflecting the second beam in accordance with an amplitude of an electric signal output from said light detecting means; and

light limiting means for permitting only light having a deflection angle within a predetermined range out of output light from said light deflecting section to pass therethrough;

wherein control timings of said light amplifying section and of said light deflection section are adjusted with the electric signal from said light detecting means such that an amplification amount in said light amplifying section and a deflection amount in said light deflecting section reflect an intensity of light passing through said light amplifying section and an intensity of light through said light deflecting sections respectively.

2. A light pulse intensity regenerating apparatus according to claim 1, wherein there is provided with a light amplifying and deflecting device capable of simultaneously carrying out a light amplification operation of said light amplifying section and a light deflection operation of said light deflecting section.

3. A light pulse intensity regenerating apparatus according to claim 1, wherein said separating means comprises a half mirror having a fixed separation ratio.

4. A light pulse intensity regenerating apparatus according to claim 1, wherein said separating means comprises a photo coupler having a fixed separation ratio.

5. A light pulse intensity regenerating apparatus according to claim 1, wherein said separating means is arranged to comprise a photo coupler made of a material having an electro-optical effect in which a separation ratio is variable according to a value of applied voltage.

6. A light pulse intensity regenerating apparatus according to claim 1, wherein said light detecting means comprises a photo detector which outputs an electric signal in accordance with an amount of received light.

7. A light pulse intensity regenerating apparatus according to claim 5, wherein said electric signal is either one of an electric current signal and a voltage signal.

8. A light pulse intensity regenerating apparatus according to claim 1, wherein said light detecting means comprises a photo detector and an amplifier for amplifying an electric signal output from the photo detector.

9. A light pulse intensity regenerating apparatus according to claim 8, wherein said electric signal is either one of an electric current signal and a voltage signal.

10. A light pulse intensity regenerating apparatus according to claim 1, wherein said light amplifying section comprises a light amplifier composed of a semiconductor laser element and an antireflection coating applied on either end face of said semiconductor laser element, and wherein the amplification factor is variable in accordance with an electric signal input from the outside.

11. A light pulse intensity regenerating apparatus according to claim 1, wherein said light amplifying section comprises a fiber light amplifier using a rare earth doped fiber in which the amplification factor is variable in accordance with an electric signal input from the outside.

12. A light pulse intensity regenerating apparatus according to claim 1, wherein said light deflecting section comprises a light deflector composed of a light deflecting element made of a material of semiconductor which changes an index of refraction by carrier induction.

13. A light pulse intensity regenerating apparatus according to claim 1, wherein said light deflecting section comprises a light deflector composed of a galvanomirror.

14. A light pulse intensity regenerating apparatus according to claim 1, wherein said light amplifying section has saturation characteristics in amplification factor of input light.

15. A light pulse intensity regenerating apparatus according to claim 1, wherein said light deflecting section has saturation characteristics in deflection angle amount of input light.

16. A light pulse intensity regenerating apparatus according to claim 1, wherein said light amplifying section comprises multiple sets of light amplifiers connected in series with each other.

17. A light pulse intensity regenerating apparatus according to claim 1, wherein said light deflecting section comprises multiple sets of light deflectors connected in series with each other.

18. A light pulse intensity regenerating apparatus according to claim 1, wherein said light limiting means is a slit vertically disposed at a predetermined deflection angle.

19. A light pulse intensity regenerating apparatus according to claim 1, wherein said light limiting means is an optical fiber vertically disposed with an end face thereof at a predetermined deflection angle.

20. A light transforming repeater comprising a light pulse intensity regenerating apparatus as set forth in claim 1 used between optical fibers in optical fiber communication system.

21. A pre-amplifier for light signal comprising a light pulse intensity regenerating apparatus as set forth in claim 1 used between optical fibers in optical fiber communication system.

22. A light intensity change measuring apparatus comprising:

a light pulse intensity regenerating apparatus as set forth in claim 1 for receiving light to be measured;

a photo detector for receiving light output from said light pulse intensity regenerating apparatus and then converting the received light into an electric signal corresponding to an amount of the received light; and

a measuring device for measuring the electric signal output from said photo detector.

23. A light intensity change measuring apparatus according to claim 22, wherein said photo detector comprises either one of a photoelectric tube, a pin photodiode, and an avalanche diode as a light detecting element.

24. A light intensity change measuring apparatus according to claim 22, wherein said measuring device is an oscilloscope.

25. A stabilized light source system comprising:

a non-stabilized light source controllable in amount of light emission with an external electric signal;

a light separator for separating light emitted from said non-stabilized light source into two beams;

a light pulse intensity regenerating apparatus as set forth in claim 1, into which one of said two separate beams is input;

a photo detector for receiving light output from said light pulse intensity regenerating apparatus and converting the light received into an electric signal corresponding to an amount of the light received; and

a feedback circuit for receiving the electric signal output from said photo detector to produce an electric signal for controlling the amount of light emission of said non-stabilized light source;

wherein the other of said two separate beams separated by said light separator is output as output light.

26. A stabilized light source system according to claim 25, wherein said light separator is either one of a half mirror and an optical fiber coupler.

27. A stabilized light source system according to claim 25, wherein said photo detector comprises either one of a photoelectric tube, a pin photodiode, and an avalanche photodiode as a light detecting element.

28. A stabilized light source system according to claim 25, wherein said feedback circuit detects a difference between a value of input electric signal and a predetermined value of electric signal and outputs an electric signal of value for compensating a change in light emission amount of said non-stabilized light source necessary for canceling the difference.