Fast variable optical delay

• US 6,674,930 B2
• Filed: 11/08/2001
• Issued: 01/06/2004
• Est. Priority Date: 01/25/1999
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Hall, Katherine L., Hakimi, Farhad, Hakimi, Hosain, Rauschenbach, Kristin A., Moriarty, Daniel T.
• Primary Examiner(s): Chang, Audrey
• Assistant Examiner(s): Curtis, Craig
• Application Number:
  US10/007,455
• Publication Number:
  US 20020061164A1
• Time in Patent Office: 789 Days
• Field of Search: 385/15, 385/24, 385/37, 385/42, 385/122, 385/127, 359/127, 359/130, 359/188, 359/290, 350/96.15
• US Class Current: 385/15
• CPC Class Codes: G02B 6/2706 as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters
• 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 6/2861 using fibre optic delay lines and optical elements associated with them, e.g. for use in signal processing, e.g. filtering delay lines in general H03H, H01P9/00; optical computing devices G06E
• CPC Class Codes: G02B 6/29346 operating by wave or beam interference interferometers for measuring G01B9/02
• CPC Class Codes: G02B 6/29356 Interference cavity within a single light guide, e.g. between two fibre gratings G02B6/29347 - G02B6/2935 take precedence; evanescent coupling to a resonator cavity G02B6/29335
• CPC Class Codes: G02B 6/29374 in an optical light guide G02B6/02214 takes precedence
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35

Abstract

A method introduces variable time offsets into a stream of optical pulses. The method includes receiving a plurality of coherent optical pulses, receiving a plurality of control signals, and forming a coherent pulse array (CPA) from each pulse in response to one of the received control signals. Temporal spacings between pulses of each CPA are responsive to the associated one of the received control signals. For optical control signals, response times can be very short. The method further includes transmitting each pulse through a dispersive optical medium. The act of transmitting makes pulses of each CPA overlap to form an interference pattern.

Claims

1. A method to introduce variable time offsets into a stream of optical pulses, comprising:

receiving a plurality of optical pulses;

receiving a plurality of control signals;

forming a coherent pulse array (CPA) from each optical pulse, temporal spacings between pulses of each CPA being responsive to one of the received control signals; and

transmitting each pulse through a dispersive optical medium, the transmitting making pulses of each CPA overlap to form an interference pattern.

2. The method of claim 1, wherein each act of forming a CPA from a pulse is responsive to the act of transmitting the same pulse.

3. The method of claim 1, wherein the transmitting includes sending the coherent pulse arrays through the dispersive optical medium.

4. The method of claim 1, further comprising sending each interference pattern through an intensity discriminator to pass a peak thereof.

5. The method of claim 4, wherein the act of sending transmits the highest intensity peak of each interference pattern.

6. The method of claim 4, wherein the act of forming further comprises:

splitting each received pulse into a plurality of pulses; and

delaying at least one of the pulses of said plurality by propagating the one of the pulses and one of the control signals in a nonlinear optical media.

7. The method of claim 6, further comprising:

eliminating the one of the control pulses from said nonlinear medium.

8. The method of claim 1, wherein the one of the pulses and one of the control signals propagate in opposite directions in the nonlinear medium.