Apparatus for compensating chromatic and polarization dispersion and frequency chirp in fiber optics and for pulse compression in laser systems

• US 5,587,827 A
• Filed: 02/01/1995
• Issued: 12/24/1996
• Est. Priority Date: 02/01/1995
• Status: Expired due to Fees

• Current Assignee: Farhad Hakimi, Hosain Hakimi
• Original Assignee: Farhad Hakimi, Hosain Hakimi
• Inventors: Hakimi, Farhad, Hakimi, Hosain
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): Robbins, Thomas
• Application Number:
  US08/381,741
• Time in Patent Office: 692 Days
• Field of Search: 359/249, 359/498, 359/499, 372/30, 372/29
• US Class Current: 359/249
• CPC Class Codes: G02B 6/2713 cascade of polarisation selective or adjusting operations
• CPC Class Codes: G02B 6/274 based on light guide birefringence, e.g. due to coupling between light guides G02B6/105, G02B6/024 take precedence; mechanically induced birefringence G02F1/0134
• CPC Class Codes: G02B 6/278 Controlling polarisation mode dispersion [PMD], e.g. PMD compensation or emulation PMD minimised transmission systems H04B10/2569
• CPC Class Codes: G02B 6/29394 Compensating wavelength dispersion G02B6/29376 takes precedence; dispersion compensated optical transmission systems H04B10/2507
• CPC Class Codes: G02F 1/0327 Operation of the cell; Circuit arrangements G02F1/05 takes precedence
• CPC Class Codes: H01S 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108
• CPC Class Codes: H04B 10/25133 including a lumped electrical or optical dispersion compensator H04B10/2519, H04B10/2525 takes precedence
• CPC Class Codes: H04B 10/2572 due to forms of polarisation-dependent distortion other than PMD

Abstract

Chromatic and polarization dispersion and transmitter frequency chirp are the dominant data rate limiting factors for high-speed, long distance communication systems. To overcome such limitations, a chromatic and polarization dispersion and frequency chirp compensator is utilized. The applicants provide a compensator by combining a wavelength to polarization transformer with a polarization to delay converter having a dispersion characteristic of substantially equivalent in magnitude, and opposite in sign, to the desired amount of dispersion and frequency chirp to be compensated. Optical gain may be incorporated in any of the elements of the compensator which makes the present invention a lightwave amplifier as well as a dispersion compensator. The present invention is also applicable as an optical pulse time compressor that compresses a relatively long width optical pulse to a short width pulse.

Claims

1. Apparatus for compensating a predetermined amount of chromatic dispersion and polarization dispersion and frequency chirp in a lightwave signal, the apparatus comprising:

first means for transforming each wavelength component of the lightwave to different respective polarization states; and

second means to convert each different respective polarization state to a different respective time delay and wherein said second means to convert is connected to an output of the first transforming means for compensating chromatic dispersion and frequency chirp of the lightwave by inducing an amount of chromatic dispersion substantially equal in magnitude, and opposite in sign, to the predetermined amount of chromatic dispersion and polarization dispersion and frequency chirp.

2. The apparatus as defined in claim 1 further comprising:

a means for amplifying the lightwave signal.

3. The apparatus as defined in claim 1 further comprising:

a means for controlling the polarization of the lightwave signal in order to produce a specific state of polarization and wherein said means for controlling the polarization is coupled to an input of the first means for transforming each wavelength component of the lightwave to different polarization state.

4. The apparatus as defined in claim 1 further comprising:

a means for repolarizing the lightwave signal and wherein said means for repolarization is connected to an output of the second means to convert each polarization state to a different respective time delay.

5. The apparatus as defined in claim 1 further comprising:

a means for depolarizing the lightwave signal and wherein said means for depolarization is connected to an input of the first means for transforming each wavelength component of the lightwave to different polarization state.

8. Apparatus for compensating a predetermined amount of chromatic dispersion and polarization dispersion and frequency chirp in a lightwave signal comprising:

a means to split the lightwave signal into two orthogonal polarization components; and

couple each said polarization components into inputs of two compensators of the claim 4; and

a means to combine two orthogonal polarization components connected to the outputs of two said compensators.

9. The apparatus as defined in claim 8 further comprising:

a means for amplifying the lightwave signal.

6. Apparatus for compensating a predetermined amount of chromatic dispersion and polarization dispersion and frequency chirp in a lightwave signal comprising:

first means to depolarize the lightwave signal; and

second means for transforming each wavelength components of the lightwave to different respective polarization states and wherein said second means for transforming is connected to an output of the first depolarizer means; and

third means to convert each polarization state to a different respective time delay for compensating chromatic dispersion and polarization dispersion and frequency chirp of the lightwave by inducing an amount of dispersion and frequency chirp substantially equal in magnitude, and opposite in sign, to the predetermined amount of dispersion and frequency chirp and wherein said third means to convert is connected to an output of the second means for transforming; and

fourth means to repolarize the lightwave to a polarized light and wherein said fourth means to repolarize is connected to an output of the third means to convert each polarization state to a different respective time delay.

7. The apparatus as defined in claim 6 further comprising:

a means for amplifying the lightwave signal.