Optical comb generator using optical white noise source

• US 5,663,822 A
• Filed: 06/14/1995
• Issued: 09/02/1997
• Est. Priority Date: 06/14/1995
• Status: Expired due to Term

• Current Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Original Assignee: MCI Incorporated (Verizon Communications Inc.)
• Inventors: Fee, John A.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): BACARES, RAFAEL D
• Application Number:
  US08/490,392
• Time in Patent Office: 811 Days
• Field of Search: 359/115, 359/120, 359/121, 359/126, 359/128, 359/132, 359/167, 359/179, 359/341, 359/161
• US Class Current: 398/95
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

A system and method for multi-wavelength modulated optical communication uses the same optical fiber without the use of multiple tuned lasers. A transmitter includes an optical comb generator and a digital modulator. The optical comb generator generates a broad spectrum of wavelengths using a white noise generator. A Fabry-Perot cavity filters the wavelengths to form a set of equally spaced resonances lambda-1 . . . lambda-n. The comb generator is locked to a particular wave length by comparing each carrier or the composite mean of the carriers to an optical reference. An error signal is generated and fed back into the into comb generator. The resonances are split into n-channels using a tree splitter. Each channel is modulated in the digital modulator. The channels are summed as an optical signal and amplified to ensure proper power levels prior to being fed to an optical fiber.

Claims

1. A transmitter for multi-wavelength modulated optical communication, comprising:

a) an optical white noise generator having an optical amplifier stimulated by a laser for providing an output of a broad spectrum of wavelengths;

b) a wavelength staggered optical bandpass filter, coupled to said optical white noise generator and responsive to said output, for generating a series of equally spaced optical information carriers in the form of a comb of optical wavelengths;

c) a digital modulator means for receiving said comb of optical wavelengths, and synchronously modulating said comb of optical wavelengths; and

d) an optical fiber coupled to said digital modulator means for transmitting said synchronously modulated comb of optical wavelengths.

2. The transmitter of claim 1, further comprising:

a plurality of bandpass filters;

reference means for locking each of said bandpass filters to a corresponding one of said optical information carriers having a particular wavelength by comparing the wavelength of said each bandpass filter to an optical reference signal derived from said comb of optical wavelengths.

3. The transmitter of claim 1, wherein said digital modulator means comprises:

an optical n-fold splitter for receiving said equally spaced optical information carriers;

a plurality of tunable optical bandpass filters coupled to the splitter;

a plurality of elemental modulators correspondingly coupled to said plurality of bandpass filters; and

an n-fold optical coupler.

4. The transmitter as claimed in claim 1, wherein said digital modulator means comprises a plurality of selectively modulated notch filters arranged in series.

5. In a transmitter for multi-wavelength modulated optical communication, said transmitter including an optical comb generator and a digital modulator means, a method of generating optical carriers for transmission via an optical fiber without using multiple tuned lasers, comprising the steps of:

a) generating a broad spectrum of wavelengths using a white noise generator;

b) using a wavelength staggered optical bandpass filter for filtering said wavelengths to form a set of equally spaced resonances lambda-1 . . . lambda-n;

c) using a tree splitter for splitting said resonances into n-channels;

d) modulating each of said n-channels in said digital modulator means; and

e) summing and amplifying said channels as an optical signal to ensure proper power levels prior to feeding said optical signal to an optical fiber.

6. The method of claim 5, wherein said step b further comprises the step of:

utilizing a Fabry-Perot comb generator for said wavelength staggered optical bandpass filter for emitting frequencies or carriers having characteristics reflective of a Fabry-Perot cavity.

7. The method of claim 6, further comprising the step of:

locking said comb generator to a particular wavelength by comparing each carrier or the composite mean of the carriers to an optical reference.

8. The method of claim 7, further comprising the step of:

sweeping an optical bandpass filter and centering said filter on the peak of each carrier.

9. The method of claim 8 further comprising the step of:

generating an error signal to be used as a feed-back to said comb generator to regulate the stability of said comb generator.

10. The method of claim 9, further comprising the steps of:

utilizing a Fabry-Perot LED for said comb generator;

utilizing a series arrangement of notch filters for the digital modulator means.