Light amplifier for use in optical communication system

Claim 2

A light amplifier comprising a first light receiving means for converting an optical input into an electrical signal, a comparator amplifier means connected to said first light receiving means for receiving the electrical output signal of said first light receiving means as one of two inputs thereto, a light emitting means connected to said comparator amplifier means for delivering an optical output signal in response to the application of the electrical output signal of said comparator amplifier means, and a second light receiving means disposed opposite to said light emitting means for converting a portion of the optical output signal of said light emitting means into an electrical signal and connected to said comparator amplifier means for applying the electrical signal in negative feedback fashion to said comparator amplifier means as the other input thereto, said comparator amplifier means driving said light emitting means in such a manner that coincidence is attained between the electrical output signals of said first and second light receiving means.

Claim 3

A light amplifier as claimed in claim 1, wherein said first and second light receiving means are packaged so that they are placed under substantially the same thermal conditions.

Claim 4

A light amplifier as claimed in claim 1, wherein a prism is provided for dividing the optical output signal of said light emitting means into two signal portions so as to apply one of the two signal portions to said second light receiving means and to derive the other signal portion as an amplified optical output.

Claim 5

A light amplifier as claimed in claim 1, wherein a glass fiber means consisting of two optical fiber portions is provided for dividing the optical output signal of said light emitting means into two signal portions so as to apply one of the two signal portions to said second light receiving means and to derive the other signal portion as an amplified optical output.

Claim 6

A light amplifier as claimed in claim 1, wherein said light emitting means comprises a first and a second light emitting elements, the optical output signal of said first light emitting element being applied to said second light receiving means to provide the negative feedback input to said comparator amplifier means, and the optical output signal of said second light emitting element being derived as an amplified optical output.

Claim 7

A light amplifier as claimed in claim 5, wherein the optical output signal of said first light emitting element is applied to said second light receiving means through a light attenuator.

Claim 8

A light amplifier as claimed in claim 5, wherein the optical output signal of said first light emitting element is applied to said second light receiving means through a pair of polarizers.

Claim 9

A light amplifier as claimed in claim 5, wherein said first and second light emitting elements are packaged so that they are placed under substantially the same thermal conditions.

Claim 10

A light amplifier comprising a first photo transistor (6) for converting an optical input (LI) applied by way of an optical transmission line (4) into an electrical signal (EI), a comparator amplifier (8) connected to said first photo transistor (6) for receiving the electrical output signal (EI) of said photo transistor (6) as one of two inputs thereto, a pair of a first and a second light emitting diodes (9, 9'') connected in series to said comparator amplifier (8) for delivering optical output signals (LO, LT) in response to the application of the output current (I) of said comparator amplifier (8), and a second photo transistor (7) disposed opposite to said second light emitting diode (9'') for converting a portion (LTI) of the optical output signal (LT) of said light emitting diode (9'') applied through a pair of polarizers (14, 14'') into an electrical signal (ET) and connected to said comparator amplifier (8) for applying the electrical signal (ET) in negative feedback fashion to said comparator amplifier (8) as the other input thereto, said comparator amplifier (8) driving said light emitting diodes (9, 9'') in such a manner that coincidence is attained between the electrical output signals (EI, ET) of said photo transistors (6, 7), and the optical output signal (LO) of said first light emitting diode (9) being delivered to another optical transmission line (5) as an amplified optical output.

Claim 11

A light amplifier comprising a first photo transistor (6) for converting an optical input (LI) applied by way of an optical transmission line (4) into an electrical signal (EI), a comparator amplifier (8) connected to said first photo transistor (6) for receiving the electrical output signal (EI) of said photo transistor (6) as one of two inputs thereto, a pair of a first and a second light emitting diodes (9, 9'') connected in series to said comparator amplifier (8) for delivering optical output signals (LO, LT) in response to the application of the output current (I) of said comparator amplifier (8), and a second photo transistor (7) disposed opposite to said second light emitting diode (9'') for converting a portion (LTI) of the optical output signal (LT) of said light emitting diode (9'') applied through a pair of polarizers (14, 14'') into an electrical signal (ET) and connected to said comparator amplifier (8) for applying the electrical signal (ET) in negative feedback fashion to said comparator amplifier (8) as the other input thereto, said comparator amplifier (8) driving said light emitting diodes (9, 9'') in such a manner that coincidence is attained between the electrical output signals (EI, ET) of said photo transistors (6, 7), and the optical output signal (LO) of said first light emitting diode (9) being delivered to another optical transmission line (5) as an amplified optical output.