Surface emitting laser and optical coherence tomography apparatus

Patent metadata

Field	Value
Publication number	US-2016013618-A1
Application number	US-201514790118-A
Country	US
Kind code	A1
Filing date	Jul 2, 2015
Priority date	Jul 11, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

In order to provide a wavelength tunable surface emitting laser capable of improving a wavelength tuning efficiency, provided is a surface emitting laser, including: a first reflector; a semiconductor cavity including an active layer; and a second reflector, the first reflector, the semiconductor cavity, and the second reflector being formed in the stated order, a gap portion being formed between the first reflector and a semiconductor layer, a cavity length being tunable, in which the surface emitting laser has a high reflectivity structure formed between the gap portion and the semiconductor cavity, and an expression of “(λ/2)×m+λ/8<L<(λ/2)×m+3λ/8” is satisfied, where L is an optical thickness of the semiconductor cavity, m is an integer of 1 or larger, and λ is a center wavelength of laser oscillation.

First claim

What is claimed is:

1 . A surface emitting laser, comprising:
a first reflector; a semiconductor cavity including an active layer; and a second reflector, the first reflector, the semiconductor cavity, and the second reflector, which are formed in the stated order, wherein a gap portion is formed between the first reflector and a semiconductor layer, wherein a cavity length is tunable, wherein the surface emitting laser has a high reflectivity structure formed between the gap portion and the semiconductor cavity, and wherein (λ/2)×m+λ/8<L<(λ/2)×m+3λ/8 is satisfied, where L is an optical thickness of the semiconductor cavity after conversion into an optical thickness in a case of no phase change in optical reflection at a first interface that is at a first reflector side of the semiconductor cavity and at a second interface that is at a second reflector side of the semiconductor cavity, m is an integer of 1 or larger, and λ is a center wavelength of laser oscillation.

2 . A surface emitting laser according to claim 1 , wherein the high reflectivity structure comprises a structure in which at least one pair of a high refractive index layer comprising a material that has a relatively high refractive index and a low refractive index layer comprising a material that has a relatively low refractive index are stacked.

3 . A surface emitting laser according to claim 1 , wherein the high reflectivity structure comprises a distribution Bragg reflector (DBR).

4 . A surface emitting laser according to claim 1 , wherein the optical thickness L of the semiconductor cavity satisfies (λ/2)×m+3λ/16<L<(λ/2)×m+5λ/16.

5 . A surface emitting laser according to claim 1 , wherein the optical thickness L of the semiconductor cavity satisfies (λ/2)×m+7λ/40≦L≦(λ/2)×m+13λ/40.

6 . A surface emitting laser according to claim 1 , wherein the optical thickness of the semiconductor cavity comprises an optical path length between an interface of the high reflectivity structure and the semiconductor cavity and an interface between the semiconductor cavity and the second reflector.

7 . A surface emitting laser according to claim 1 , wherein the semiconductor cavity comprises a stacked body of all semiconductor layers placed between the high reflectivity structure and the second reflector.

8 . A surface emitting laser according to claim 1 , wherein the high reflectivity structure has a reflectivity of 50% or more at the center wavelength of the laser oscillation.

9 . An apparatus, comprising:
a surface emitting laser, comprising:
a first reflector;
a semiconductor cavity including an active layer; and
a second reflector,
the first reflector, the semiconductor cavity, and the second reflector, which are formed in the stated order,
wherein a gap portion is formed between the first reflector and a semiconductor layer,
wherein a cavity length is tunable,
wherein the surface emitting laser has a high reflectivity structure formed between the gap portion and the semiconductor cavity, and
wherein (λ/2)×m+λ/8<L<(λ/2)×m+3λ/8 is satisfied, where L is an optical thickness of the semiconductor cavity after conversion into an optical thickness in a case of no phase change in optical reflection at a first interface that is at a first reflector side of the semiconductor cavity and at a second interface that is at a second reflector side of the semiconductor cavity, m is an integer of 1 or larger, and λ is a center wavelength of laser oscillation and
an information acquisition portion configured to acquire information on an inside of an object to be measured.

10 . The apparatus according to claim 9 , further comprising:
an interference optical system configured to branch light from a light source device into irradiation light to be irradiated to an object to be measured and reference light, and generate coherent light by reflection of light irradiated to the object to be measured and the reference light; and a light detection portion configured to receive the coherent light, wherein the information acquisition portion acquires information on the object to be measured based on a signal from the light detection portion.

11 . A surface emitting laser, comprising:
a first reflector; a semiconductor cavity including an active layer; and a second reflector,
the first reflector, the semiconductor cavity, and the second reflector being formed in the stated order,
wherein a gap portion is formed between the first reflector and a semiconductor layer, wherein a cavity length is tunable, wherein the surface emitting laser has a high reflectivity structure formed between the gap portion and the semiconductor cavity, and wherein (λ/2)×m+λ/8<L<(λ/2)×m+3λ/8 is satisfied, where L is an optical thickness of the semiconductor cavity, m is an integer of 1 or larger, and λ is a center wavelength of laser oscillation.

12 . A surface emitting laser according to claim 11 , wherein the high reflectivity structure comprises a structure in which at least one pair of a high refractive index layer comprising a material that has a relatively high refractive index and a low refractive index layer comprising a material that has a relatively low refractive index are stacked.

13 . A surface emitting laser according to claim 11 , wherein the high reflectivity structure comprises a distribution Bragg reflector (DBR).

14 . A surface emitting laser according to claim 11 , wherein the optical thickness L of the semiconductor cavity satisfies (λ/2)×m+3λ/16<L<(λ/2)×m+5λ/16.

15 . A surface emitting laser according to claim 11 , wherein the optical thickness L of the semiconductor cavity satisfies (λ/2)×m+7λ/40≦L≦(λ/2)×m+13λ/40.

16 . A surface emitting laser according to claim 11 , wherein the optical thickness of the semiconductor cavity comprises an optical path length between an interface of the high reflectivity structure and the semiconductor cavity and an interface between the semiconductor cavity and the second reflector.

17 . A surface emitting laser according to claim 11 , wherein the semiconductor cavity comprises a stacked body of all semiconductor layers placed between the high reflectivity structure and the second reflector.

18 . A surface emitting laser according to claim 11 , wherein the high reflectivity structure has a reflectivity of 50% or more at the center wavelength of the laser oscillation.

19 . An apparatus, comprising:
a surface emitting laser, comprising: a first reflector; a semiconductor cavity including an active layer; and a second reflector,
the first reflector, the semiconductor cavity, and the second reflector being formed in the stated order,
wherein a gap portion is formed between the first reflector and a semiconductor layer, wherein a cavity length is tunable, wherein the surface emitting laser has a high reflectivity structure formed between the gap portion and the semiconductor cavity, and wherein (λ/2)×m+λ/8<L<(λ/2)×m+3λ/8 is satisfied, where L is an optical thickness of the semiconductor cavity, m is an integer of 1 or larger, and λ, is a center wavelength of laser oscillation; and an information acquisition portion configured to acquire information on an inside of an object to be measured.

20 . The apparatus according to claim 19 , further comprising:
an interference optical system configured to branch light from a light source device into irradiation light to be irradiated to an object to be measured and reference light, and generate coherent light by reflection of light i

Assignees

• Canon Kk

Inventors

• Nagatomo Yasuhiro

Classifications

• H01S5/18361

  Structure of the reflectors, e.g. hybrid mirrors · CPC title

• H01S5/18363

  comprising air layers · CPC title

• H01S5/18333

  only above the active layer · CPC title

• H01S5/187

  using Bragg reflection · CPC title

• H01S5/18366 Primary

  Membrane DBR, i.e. a movable DBR on top of the VCSEL · CPC title