Optical telephone using optical modulator

• US 5,357,362 A
• Filed: 05/07/1993
• Issued: 10/18/1994
• Est. Priority Date: 02/13/1991
• Status: Expired due to Fees

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Azuma, Yuji, Shibata, Yoshihiro, Kuwahara, Akio, Tamura, Shinji, Fukuda, Akira, Kuwaki, Nobuo, Ikawa, Nobuhiro
• Primary Examiner(s): PASCAL, LESLIE C
• Application Number:
  US08/059,467
• Time in Patent Office: 529 Days
• Field of Search: 359/149-151, 359/188, 359/195, 359/173, 385/4, 385/13
• US Class Current: 398/134
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 6/2852 using tapping light guides arranged sidewardly, e.g. in a non-parallel relationship with respect to the bus light guides (light extraction or launching through cladding, with or without surface discontinuities, bent structures)
• CPC Class Codes: H04B 10/505 using external modulation

Abstract

An optical modulation method operable in an optical transmission path using an optical fiber, wherein an optical fiber bending region is formed by bending a portion of the optical fiber into a U shape having a predetermined bending width. A bending width set point is set in correspondence with a predetermined inclined portion of a characteristic curve representing a dependency ratio of insertion loss of light propagating in said optical fiber bending region relative to the bending width thereof, said predetermined inclined portion of said characteristic curve being located between a predetermined maximum and minimum portion thereof. Intensity modulation of light propagating in the optical fiber is performed using a signal to be transmitted by adjusting the bending width of the optical fiber bending region in correspondence with the signal to be transmitted with reference to the bending width set point as a center. An optical telephone uses an optical modulator including an optical fiber having a U-shaped bending region and a transducer for vibrating one straight portion of the optical fiber.

Claims

1. An optical telephone comprising:

an optical modulator including optical fiber guide means for guiding an optical fiber having a U-shaped bending region formed in an optical transmission path, means for adjusting a bending width of said optical fiber so as to cause an increase in the amount of change in a bending loss with respect to a change in the bending width, thereby increasing the degree of modulation, and electromagnetic transducer means for vibrating one straight portion of said optical fiber;

means, electrically connected to said electromagnetic transducer means, for modulating a voice into an electrical signal and for supplying the electrical signal to said electromagnetic transducer means; and

means, arranged near said bending region of said optical fiber, for receiving light leaking from said bending region, for converting the light into an electrical signal, and for demodulating the electrical signal into a voice.

2. A telephone according to claim 1, wherein said electromagnetic transducer means comprises a speaker.