1. A laser structure, comprising:
a semiconductor gain region configured to emit radiation at a central laser wavelength;
a pump source configured to emit a pump radiation beam at a central pump wavelength directed toward the gain region;
a first reflector comprising a distributed Bragg reflector (DBR) disposed in the pump radiation beam, the first reflector having reflectivity greater than about 90% across a bandwidth of less than about 60 nm centered at the central laser wavelength, the first reflector also having a reflectivity less than about 50% at the central pump wavelength;
a second reflector, wherein the gain region is disposed between the first reflector and the second reflector.
2. The laser structure of claim 1, wherein the first reflector comprises a number of layer pairs, each layer pair including a first layer and a second layer, wherein an optical thickness of the first layer is \xbe of the central laser wavelength and an optical thickness of the second layer is \xbe of the central laser wavelength.
3. The laser structure of claim 2, wherein a number of layer pairs is greater than about 6.
4. The laser structure of claim 1, wherein the first reflector comprises alternating layers of non-epitaxial, dielectric materials.
5. The laser structure of claim 1, wherein the first reflector comprises alternating layers of epitaxially grown semiconductor materials.
6. The laser structure of claim 1, wherein the first reflector comprises:
a first portion having a first thermal conductivity; and
a second portion having a second thermal conductivity that is less than the first thermal conductivity.
7. The laser structure of claim 6, wherein:
the first portion comprises alternating layers of epitaxially grown semiconductor materials; and
the second portion comprises alternating layers of non-epitaxial, dielectric materials.
8. The laser structure of claim 1, wherein the central pump radiation wavelength is between about 370 and about 530 nm and the peak laser wavelength is in a range of about 390 to about 550 nm.
9. The laser structure of claim 1, wherein the pump radiation beam is incident on a surface of the first reflector at an angle with respect to normal to the surface of the first reflector.
10. The laser structure of claim 9, wherein the angle is about 25 to about 30 degrees or about 35 to about 40 degrees and the first reflector has reflectivity less than about 25% at the pump wavelength of about 405 nm.
11. The laser structure of claim 9, wherein the pump radiation beam is incident on the first reflector at an angle of about 43 degrees and the first reflector has reflectivity less than about 25% at the pump wavelength of about 445 nm.
12. The laser structure of claim 1, wherein the second reflector has a reflectivity greater than 90% for both the peak pump wavelength and the peak laser wavelength.
13. The laser structure of claim 1, wherein the laser gain region comprises InGaN quantum well layers.
14. A laser structure, comprising:
a semiconductor gain region configured to emit radiation at a central laser wavelength;
a pump source configured to emit a pump radiation beam at a central pump wavelength directed toward the gain region;
a heat sink;
a first reflector comprising a distributed Bragg reflector (DBR) disposed proximate the heat sink, the first reflector having a thermal conductivity that varies with distance from the heat sink;
a second reflector, wherein the gain region is disposed between the first reflector and the second reflector.
15. The laser structure of claim 14, wherein a first portion of the first reflector has a first thermal conductivity and a second portion of the first reflector has a second thermal conductivity that is lower than the thermal conductivity of the first portion, wherein the first portion is closer to the gain region than the second portion.
16. The laser structure of claim 15, wherein:
the first portion comprises alternating layers of epitaxially grown semiconductor materials; and
the second portion comprises alternating layers of non-epitaxial, dielectric materials.
17. A semiconductor laser structure, comprising:
a semiconductor gain region having a first side and a second side and configured to emit radiation at a central laser wavelength;
a pump source configured to emit a pump radiation beam at a central pump wavelength directed toward the gain region;
a first reflector comprising a distributed Bragg reflector (DBR) arranged proximate the first side of the gain region and in the pump radiation beam;
a reflecting surface disposed proximate the second side of the gain region;
a second reflector; and
an air gap between the second reflector and the reflecting surface.
18. The semiconductor laser structure of claim 17, wherein:
the first reflector having reflectivity greater than about 90% across a bandwidth of less than about 60 nm centered at the central laser wavelength, the first reflector also having a reflectivity less than about 50% at the central peak pump wavelength.
19. The laser structure of claim 17, further comprising positioning elements configured to adjust a thickness of the air gap.
20. The laser structure of claim 17, wherein the pump radiation beam comprises multiple modes and the laser radiation comprises a single mode.
21. The laser structure of claim 17, wherein the reflecting surface is a surface of a substrate remnant upon which the gain region is epitaxially grown.
22. The laser structure of claim 17, wherein the second reflector is disposed on a substrate that is substantially transparent to radiation at the central laser wavelength.
23. A method, comprising:
operating a laser comprising a semiconductor gain region configured to emit radiation at a central laser wavelength, first and second reflectors and a reflecting surface disposed proximate to the gain regions, the first and second reflectors defining a primary laser cavity and the reflecting surface and the second reflector defining a secondary optical cavity;
operating a pump source configured to emit pump radiation having a number of input modes, the pump radiation directed toward and at least partially absorbed in the semiconductor gain region; and
adjusting a gap between the reflecting surface and the second reflector until the laser outputs a number of output modes that is less than the number of input modes.
24. The method of claim 23, wherein the number of output modes is only one.
25. The method of claim 23, wherein adjusting the gap comprises increasing or decreasing a length of a secondary cavity until the laser outputs one or more selected output modes.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of tracing the activity of an expression, said method comprising the machine-implemented steps of:
(a) receiving, from a user, a specification of a machine-implemented process in which a trigger expression resulting in an L value during the machine-implemented process is to be traced;
(b) receiving, from a user, a specification of the trigger expression to be traced in the machine-implemented process, said trigger expression representing a non-executable data value having a state;
(c) responsive to steps (a) and (b), monitoring execution of said machine-implemented process without altering a logic flow of said machine-implemented process to detect occurrences of a plurality of references to a location in machine memory representing a state of said trigger expression, wherein each said occurrence of a reference to a location in machine memory representing a state of said trigger expression occurs as a result of executing said machine-implemented process;
(d) responsive to each detected occurrence of a reference to said location in machine memory representing a state of said trigger expression, storing the respective state of the trigger expression at the time of the respective detected occurrence of a reference to said location in machine memory representing a state of said trigger expression to create a history of said trigger expression within the machine-implemented process, said storing step being performed without interrupting the machine-implemented process; and
(e) restoring the state of the trigger expression when requested.
2. The method of claim 1, further comprising:
(a) imposing a condition onto the trigger expression; and
(b) storing the state of the trigger expression only when the condition is satisfied.
3. The method of claim 1, further comprising:
(a) displaying the history such that the state of the trigger expression each time the trigger expression was active can be displayed separately.
4. The method of claim 1, wherein the reference to said location in machine memory representing a state of said trigger expression is a Read andor a Write.
5. The method of claim 1, further comprising:
(a) receiving, from a user, a specification of at least one attached expression;
(b) responsive to each detected occurrence of a reference to said location in machine memory representing a state of said trigger expression, storing the respective state of the at least one attached expression at the time of the respective detected occurrence of a reference to said location in machine memory representing a state of said trigger expression, the states of the at least one attached expression being associated with said history of said trigger expression within the machine-implemented process; and
(c) restoring the state of the at least one attached expression when requested.
6. The method of claim 1, wherein the machine-implemented process is a computer program.
7. A method of tracing the activity of an expression in an executing computer program, said method comprising the machine-implemented steps of:
(a) receiving, from a user, a specification of the computer program in which a trigger expression resulting in an L value during the execution of the computer program is to be traced;
(b) receiving, from a user a specification of the trigger expression and any optional attachment expressions to be traced in the computer program, said trigger expression representing a non-executable data value having a state;
(c) imposing a condition onto the trigger expression;
(d) responsive to steps (a) and (b), monitoring execution of said computer program to detect occurrences of a plurality of accesses to a location in memory containing a state representing said trigger expression, wherein each said occurrence of an access to a location in memory containing a state representing said trigger expression occurs as a result of executing said computer program;
(e) responsive to each detected occurrence of an access to said location in memory containing a value representing said trigger expression, if said condition is satisfied, then storing the respective state of the trigger expression and any optional attachment expressions at the time of the respective detected occurrence of an access to said location in memory containing a state representing the trigger expression to create a snapshot corresponding to the respective detected occurrence of an access to said location in memory, the step of storing being accomplished without interrupting the process;
(f) creating a profile of the trigger expression comprising storing each snapshot;
(g) displaying the profile such that each snapshot can be displayed separately; and
(h) restoring the state of each snapshot, when requested.