Nonequilibrium pulsed femtosecond semiconductor disk laser

Patent metadata

Field	Value
Publication number	US-9853417-B2
Application number	US-201615264335-A
Country	US
Kind code	B2
Filing date	Sep 13, 2016
Priority date	Sep 22, 2014
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A surface-emitting semiconductor laser system contains at least one MQW unit of at least three constituent QWs, axially separated from one another substantially non-equidistantly. The MQW unit is located within the axial extent covered, in operation of the laser, by a half-cycle of the standing wave of the field at a wavelength within the gain spectrum of the gain medium; immediately neighboring nodes of the standing wave are on opposite sides of the MQW unit. So-configured MQW unit can be repeated multiple times and/or complemented with individual QWs disposed outside of the half-cycle of the standing wave with which such MQW unit is associated. The semiconductor laser further includes a pump source configured to input energy in the semiconductor gain medium and a mode-locking element to initiate mode-locking.

First claim

What is claimed is:

1. A surface-emitting semiconductor laser system configured to operate in a mode-locked regime, the laser system comprising:
an optical resonator having an optical axis;
a semiconductor laser chip within the optical resonator, the semiconductor laser chip containing a semiconductor gain medium,
wherein said semiconductor gain medium is characterized by a gain spectrum, the gains spectrum having a bandwidth that includes a first wavelength,
wherein said semiconductor gain medium has a first multiple quantum well (MQW) unit, said first MQW unit defined by a sequence of at least three first quantum wells (QWs) that are spaced substantially non-equidistantly with respect to one another;

and
a pump source in operable communication with said semiconductor laser chip and configured to pump energy to the semiconductor gain medium to produce excited-state carriers in the first MQW unit,
wherein said semiconductor laser system is configured to form a standing optical wave within said semiconductor laser chip at a frequency of the first wavelength, said standing optical wave having first and second immediately neighboring modes located along the optical axis within the semiconductor gain medium, said first and second nodes formed on the opposite sides of said first MQW unit.

2. A laser system according to claim 1 , wherein the first MQW unit is positioned asymmetrically between the first and second immediately neighboring nodes.

3. A laser system according to claim 1 , further comprising a mode-lock element disposed in optical communication with the laser chip and configured to define mode-locked pulses of optical radiation inside said optical resonator when said energy is pumped to the laser chip.

4. A laser system according to claim 3 , wherein the mode-lock element comprises at least one of a semiconductor saturable absorber mirror element, a self-phase modulation Kerr lens element, and an active modulation element.

5. A laser system according to claim 1 , wherein said laser system is configured to define durations, of said mode-locked pulses, each of which durations is shorter than one hundred femtoseconds.

6. A laser system according to claim 1 ,
wherein two neighboring QWs from said at least three first QWs are separated from one another by a first confinement barrier material, the first confinement barrier material having a first thickness that is smaller than a thickness of a QW from the first QWs to delocalize at least one carrier wavefunction over more than one first QW.

7. A laser system according to claim 1 , wherein an overall thickness of said first MQW unit, measured along the optical axis, is greater than a half of a distance between the first and second immediately neighboring nodes of said standing optical wave.

8. A laser system according to claim 1 , wherein the semiconductor gain medium includes a base material that is a compound semiconductor comprising a combination of elements from (i) groups III and V of the periodic table, or (ii) groups II and VI of the periodic table.

9. A laser system according to claim 1 , wherein the pump source is configured to electrically create electrons in a conduction band of the semiconductor gain medium.

10. A laser system according to claim 1 , wherein the pump source includes a (p-and-n) doped semiconductor chip.

11. A laser system according to claim 1 , further comprising an optical system configured as at least one of a single-pass optical pumping system, a multi-pass Z-cavity optical pumping system, a multi-pass V-cavity optical pumping system, and a linear cavity optical pumping system,
said optical system positioned to define optical communication between the semiconductor gain medium and the pump source to create electrons in a conduction band of the semiconductor gain medium with radiation from the pump source.

12. A laser system according to claim 1 ,
wherein said standing optical wave has third and fourth nodes located along the optical axis within the gain medium, said third and fourth nodes being immediately neighboring to one another,
wherein said gain medium includes a second MQW unit, said second MQW unit containing at least one second QW, said second MQW unit located between the third and fourth nodes, and
wherein the pump source is configured to pump energy to the gain medium to produce excited carriers in all MQW units present in the laser system.

13. A laser system according to claim 12 , wherein said at least one second QW includes at least three second QWs that are spaced substantially non-equidistantly with respect to one another.

14. A laser system according to claim 12 ,
wherein a reflector of the optical resonator includes a distributed Bragg reflector (DBR) integrated with the gain medium,
wherein said second and third nodes are immediately neighboring to one another such that the first, second, third, and fourth nodes form a sequence of nodes in which the first node is the closest to the DBR;
wherein the first MQW unit includes four first QWs, the second MQW unit includes at least three second QWs; and
further comprising a third MQW unit containing multiple third QWs, said third MQW unit located between the second and third nodes.

15. A laser system according to claim 14 , QWs of at least one of the second and third MQW units are spaced substantially non-equidistantly with respect to one another.

16. A laser system according to claim 1 , wherein
said standing optical wave has a third node located along the optical axis within the gain medium, said second and third nodes being immediately neighboring with respect to one another,
and wherein said gain medium includes a second MQW unit, said second MQW unit containing a sequence of at least three second QWs, all of said at least three second QWs located between the second and third nodes.

17. A laser system according to claim 16 , wherein said at least three second QWs are separated from one another substantially non-equidistantly.

18. A laser system according to claim 1 , wherein a reflector of the optical resonator has a reflectance exceeding 99% at the first wavelength, said reflector being one of a distributed Bragg reflector and a simple reflector.

19. A laser system according to claim 18 ,
wherein said optical resonator further comprises an output coupler configured to transmit radiation, generated with the gain medium, outside the optical resonator,
wherein said reflector is in integrated with the semiconductor gain medium, and
wherein said laser system contains a space between the laser chip and the output coupler.

20. A laser system according to claim 1 ,
wherein said standing optical wave has third and fourth nodes located along the optical axis, the third node located within a space occupied by a reflector of the optical resonator, the fourth node located within the gain medium, said third and fourth nodes being immediately neighboring to one another,
wherein said gain medium includes a second MQW unit, said second MQW unit containing at least one second QW, said second MQW unit located between the third and fourth nodes, and
wherein the pump source is configured to pump energy to the gain medium to produce excited carriers in all MQW units present in the laser system.

Assignees

• Univ Arizona

Inventors

• Kilen Isak R
• Koch Stephan W
• Moloney Jerome V

Classifications

• H01S5/14

  External cavity lasers (H01S5/18 takes precedence; mode locking H01S5/065) · CPC title

• H01S5/187

  using Bragg reflection · CPC title

• H01S5/0657 Primary

  Mode locking, i.e. generation of pulses at a frequency corresponding to a roundtrip in the cavity · CPC title

• H01S3/1118

  Semiconductor saturable absorbers, e.g. semiconductor saturable absorber mirrors [SESAMs]; Solid-state saturable absorbers, e.g. carbon nanotube [CNT] based · CPC title

• H01S3/1115

  using intracavity saturable absorbers · CPC title