Amplification of ultrashort pulses with Nd:glass amplifiers pumped by alexandrite free running laser

• US 5,235,606 A
• Filed: 10/29/1991
• Issued: 08/10/1993
• Est. Priority Date: 10/29/1991
• Status: Expired due to Term

• Current Assignee: Laser Energetics, Inc., Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Alliedsignal Inc., University of Michigan
• Inventors: Squier, Jeffrey, Coe, John S., Harter, Donald J., Mourou, Gerard A.
• Primary Examiner(s): Scott, Jr., Leon
• Application Number:
  US07/784,232
• Time in Patent Office: 651 Days
• Field of Search: 372/69, 372/25, 372/29, 372/30, 372/31, 372/20, 359/559, 359/154
• US Class Current: 372/25
• CPC Class Codes: H01S 2301/04 Gain spectral shaping, flattening
• 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: H01S 3/094 by coherent light
• CPC Class Codes: H01S 3/17 amorphous, e.g. glass
• CPC Class Codes: H01S 3/2316 Cascaded amplifiers

Abstract

A system for producing ultra-high peak power pulses employs a plurality of solid state amplifying materials, such as Nd:glass, alexandrite, and Ti:sapphire, to achieve stretching of a pulse prior to amplification by a factor of approximately between 100 and 10,000. The time-stretched pulse is amplified by many orders of magnitude, illustratively 10⁹. After time-stretching and amplification, the pulse is then recompressed to its original duration. Pumping of the multiple solid-state elements is performed simultaneously using an alexandrite laser which is tunable between approximately 700 and 800 nm. The pumping energy has a pulse duration which is less than the fluorescence lifetime of the excited solid-state media.

Claims

1. A method of producing an ultra-high peak power pulse, the method comprising the steps of:

receiving a short optical pulse having a predetermined duration from an optical oscillator;

stretching in time the short optical pulse by a factor of approximately between 100 and 10,000 to produce a time-stretched optical pulse to be amplified;

amplifying the time-stretched optical pulse in a solid state amplifying media, said step of amplifying additionally including the step of combining the time-stretched optical pulse with an optical energy generated by a laser used to pump the solid-state amplifying media; and

compressing in time the amplified time-stretched optical pulse, whereby the amplitude of the resulting amplified time-stretched compressed optical pulse is increased.

2. The method of claim 1 wherein said step of amplifying is performed at an amplification factor of at least 10³.

3. The method of claim 1 wherein said step of compressing is performed to an extent whereby the amplified time-stretched compressed optical pulse is returned to the predetermined duration of the short optical pulse from the optical oscillator.

4. The method of claim 1 wherein said step of amplifying is performed in Nd:

glass.

5. The method of claim 4 wherein said step of amplifying comprises the step of pumping said Nd:

glass material.

6. The method of claim 5 wherein said step of pumping comprises the further step of energizing an alexandrite laser.

7. The method of claim 6 wherein said step of energizing comprises the further step of flash lamp pumping said alexandrite laser.

8. The method of claim 6 wherein said step of pumping is preformed at an approximate wavelength selected from 740 nm, 800 nm, and 820 nm.

9. The method of claim 6 wherein said step of pumping is performed using a pulse duration which is shorter than the lifetime of an excited state of said Nd:

glass rods.

10. The method of claim 9 wherein said pulse duration is approximately between 50 and 100 μ

s.

11. The method of claim 6 wherein there is further provided the step of tuning said alexandrite laser within a range of approximately between 700 and 800 nm.

12. A system for producing an ultra-high peak power optical pulse, the system comprising:

an optical oscillator for producing a short optical pulse having a predetermined duration;

a plurality of glass rods, of the type which produce optical amplification, disposed in an optically serial arrangement having first and second ends, said plurality of glass rods being arranged at said first end thereof to receive said optical pulse from said optical oscillator, and at said second end thereof to output an amplified output pulse which has a duration longer than said predetermined duration of said short optical pulse from said optical oscillator;

optical pump means for optically pumping said plurality of glass rods simultaneously, said optical pump means being formed of an alexandrite laser; and

compressor means for reducing the duration of the amplified output pulse and producing at an output thereof the ultra-high peak power optical pulse.

13. The system of claim 12 wherein there is further provided optical means for receiving the optical pulse from said optical oscillator and a pumping energy from said optical pump means, said optical means being coupled optically to said first end of said plurality of glass rods.

14. The system of claim 12 wherein said alexandrite laser operates in a free-running mode.

15. The system of claim 12 wherein said glass rods are formed of Nd:

glass.

16. The system of claim 15 wherein said Nd:

glass rods are formed of respectively different types of glass, so as to have respectively different central frequency characteristics.

17. The system of claim 15 wherein said optical pumping means is a tunable optical pumping means, said tunable optical pumping means being tunable within a range of approximately between 700 and 800 nm.

18. The system of claim 12 wherein said short optical pulse from said optical oscillator is a chirped pulse.