Self-standing parallel plate beam splitter, method for manufacturing the same, and laser diode package structure using the same

• US 8,235,605 B2
• Filed: 03/18/2008
• Issued: 08/07/2012
• Est. Priority Date: 03/19/2007
• Status: Expired due to Fees

• Current Assignee: Jeong Soo Kim
• Original Assignee: Jeong Soo Kim
• Inventors: Kim, Jeong Soo
• Primary Examiner(s): Healy, Brian
• Application Number:
  US12/531,950
• Publication Number:
  US 20100226655A1
• Time in Patent Office: 1,603 Days
• Field of Search: 385/31, 385/88, 385/89, 385/92, 385/93, 385/94, 385/49, 385/36, 359/260, 359/261, 359/528, 359/546, 359/639, 359/640, 359/629, 398/135, 398/136, 398/137, 398/138, 398/139, 427/162, 430/321
• US Class Current: 385/92
• CPC Class Codes: G02B 27/1006 for splitting or combining different wavelengths G02B27/1086, G02B27/141 take precedence
• CPC Class Codes: G02B 27/1073 characterized by manufacturing or alignment methods
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 6/29361 Interference filters, e.g. multilayer coatings, thin film filters, dichroic splitters or mirrors based on multilayers, WDM filters
• CPC Class Codes: G02B 6/4206 Optical features G02B6/4207, G02B6/421 take precedence
• CPC Class Codes: G02B 6/4214 the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device G02B6/4246 takes precedence
• CPC Class Codes: G02B 6/4215 the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers G02B6/4246 takes precedence
• CPC Class Codes: G02B 6/4246 Bidirectionally operating package structures
• CPC Class Codes: H01L 2224/05144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05166 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/05169 Platinum [Pt] as principal constituent
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/14 of a plurality of bump connectors
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01S 5/005 : Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• CPC Class Codes: H01S 5/02208 : characterised by the shape of the housings
• CPC Class Codes: H01S 5/02212 : Can-type, e.g. TO-CAN housings with emission along or parallel to symmetry axis
• CPC Class Codes: H01S 5/02251 : using optical fibres
• CPC Class Codes: H01S 5/02253 : using lenses
• CPC Class Codes: H01S 5/02255 : using beam deflecting elements
• CPC Class Codes: H01S 5/02325 : Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/02415 : by using a thermo-electric cooler [TEC], e.g. Peltier element
• CPC Class Codes: H01S 5/02438 : Characterized by cooling of elements other than the laser chip, e.g. an optical element being part of an external cavity or a collimating lens
• CPC Class Codes: H01S 5/0683 : by monitoring the optical output parameters
• CPC Class Codes: H01S 5/0687 : Stabilising the frequency of the laser
• CPC Class Codes: H01S 5/4012 : Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4025 : Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence
• CPC Class Codes: H01S 5/4056 : emitting light in more than one direction

Abstract

Disclosed herein are a self-standing parallel plate beam splitter, a method for manufacturing the same, and a laser diode package structure using the same. The self-standing parallel plate beam splitter according to the present invention is easy to manufacture and is applicable to various laser diode packages, thereby enabling easy implementation of a laser diode package that is capable of performing bidirectional communication, a laser diode package having a triplexer function, a laser diode package having a wavelength locking function, and a laser diode package having a front side monitoring function to monitor the operation state of a laser diode chip using some of laser light emitted from the front side of the laser diode chip.

Claims

1. A self-standing parallel plate beam splitter for performing a function to divide light incident thereon by reflecting or transmitting the light depending upon a wavelength of the light, wherein the self-standing parallel plate beam splitter is constructed in a structure in which a front side incline plane and a back side incline plane formed at opposite sides of a substrate is at an angle of 45 degrees to a bottom plane of the substrate, whereby, when the bottom plane of the substrate is attached to a top plane of a sub mount having a flat bottom plane, the front side incline plane and the back side incline plane are at a tilt angle of 45 degrees to the top plane of the sub mount, and dielectric thin films or metal thin films are deposited on the front side incline plane and the back side incline plane such that the front side incline plane and the back side incline plane have transmissivity or reflexibility of a ratio predetermined with respect to light of a specific wavelength.

2. The self-standing parallel plate beam splitter according to claim 1, wherein a cutting plane is formed between the front side incline plane and the bottom plane of the self-standing parallel plate beam splitter to partially cut the front side incline plane and the bottom plane.

3. A method of manufacturing a self-standing parallel plate beam splitter according to claim 1, the method comprising:

(a) cutting a silicon wafer from a silicon ingot such that the silicon wafer is tilted 9.74 degrees with respect to a plane and applying photo resist on a portion of a top plane of the silicon wafer;

(b) removing the photo resist at a region to be etched of the silicon wafer by photolithography;

(c) etching the region where the photo resist is removed using an anisotropic etching solution such that the exposed planes are formed as planes having a tilt angle of 54.74 degrees to the plane;

(d) depositing a dielectric thin film or a metal thin film on a bottom plane of the silicon wafer such that the bottom plane of the silicon wafer has transmissivity or reflexibility of a ratio predetermined according to a wavelength of incident light;

(e) depositing a dielectric thin film or a metal thin film on the top plane, including the planes, of the silicon wafer such that the top plane, including the planes, of the silicon wafer has transmissivity or reflexibility of a ratio predetermined according to a wavelength of incident light; and

(f) cutting the silicon wafer to complete the self-standing parallel plate beam splitter.

4. A method of manufacturing a self-standing parallel plate beam splitter according to claim 1, the method comprising:

(a) depositing a dielectric thin film or a metal thin film on one plane of a silicon or glass parallel plate such that the one plane of the silicon or glass parallel plate has transmissivity or reflexibility of a ratio predetermined according to a wavelength of incident light;

(b) depositing a dielectric thin film or a metal thin film on the other plane of the silicon or glass parallel plate such that the other plane of the silicon or glass parallel plate has transmissivity or reflexibility of a ratio predetermined according to a wavelength of incident light; and

(c) sawing the parallel plate such that the parallel plate has an angle of 45 degrees to the section of the parallel plate to complete the self-standing parallel plate beam splitter.

5. The method according to claim 4, wherein the step of (c) sawing the parallel plate includes sawing the parallel plate using a 45-degree wedge-type rotary saw having a protrusion at the section thereof to form a cutting plane for cutting the bottom plane and the incline plane between the bottom plane and the incline plane.

6. The method according to claim 4, wherein the step of (c) sawing the parallel plate includes sawing the parallel plate by dry etching or laser.

7. A bidirectional-communication laser diode package structure having a self-standing parallel plate beam splitter according to claim 1, a laser diode chip, and a receiving photo diode chip mounted in a package housing, wherein a front side incline plane of the self-standing parallel plate beam splitter is coated with a single dielectric thin film or a plurality of dielectric thin films having different refractive indexes to reflect laser light of a wavelength emitted from the laser diode chip and exit the reflected laser light to an optical fiber outside the package and to transmit laser light of a wavelength incident from the optical fiber outside the package and forward the transmitted laser light to the receiving photo diode chip.

8. A TO type laser diode package structure constructed in a structure in which a laser diode chip is disposed at one side of a front side incline plane of a self-standing parallel plate beam splitter according to claim 1, and a light receiving device for monitoring is disposed at the other side of a back side incline plane of the self-standing parallel plate beam splitter, wherein the front side incline plane of the self-standing parallel plate beam splitter is coated with a single dielectric thin film or a plurality of dielectric thin films having different refractive indexes to reflect some of laser light emitted from the front side of the laser diode chip and exit the reflected laser light out of the package, and the remaining laser light, not reflected at the front side incline plane, is transmitted through the front side incline plane, and is irradiated to a monitoring photo diode chip through the back side incline plane, whereby the operation state of the laser diode chip is monitored using some of the laser light emitted from the front side of the laser diode chip.

9. A bidirectional-communication triplexer laser diode package structure having a self-standing parallel plate beam splitter according to claim 1, a laser diode chip, and two receiving photo diode chips mounted in a package housing, wherein the laser diode chip, for emitting light toward a front side incline plane of the self-standing parallel plate beam splitter, is disposed at the side of the self-standing parallel plate beam splitter, one of the receiving photo diode chips, for receiving laser light of a 1490 nm band wavelength incident from an optical fiber through a back side incline plane of the self- standing parallel plate beam splitter, and the other receiving photo diode chip, for receiving laser light of a 1550 nm band wavelength incident from the optical fiber through the back side incline plane, are disposed below the back side incline plane.

10. The laser diode package structure according to claim 9, wherein the front side incline plane of the self-standing parallel plate beam splitter transmits laser light of a 1310 nm band wavelength and reflects laser light of a 1490 nm band wavelength, and the back side incline plane of the self-standing parallel plate beam splitter transmits laser light of a 1310 nm band wavelength and laser light of a 1490 nm band wavelength and reflects laser light of a 1550 nm band wavelength.

11. A bidirectional-communication triplexer laser diode package structure having two self-standing parallel plate beam splitters according to claim 1, a laser diode chip, and two receiving photo diode chips mounted in a package housing, wherein a self-standing parallel plate beam splitter for a 1490 nm band wavelength, which transmits laser light of a wavelength emitted from the laser diode chip and reflects laser light of a 1490 nm band wavelength incident from an optical fiber downward, and a self-standing parallel plate beam splitter for a 1550 nm band wavelength, which transmits laser light of a wavelength emitted from the laser diode chip and laser light of a 1490 nm band wavelength incident from the optical fiber and reflects laser light of a 1550 nm band wavelength incident from the optical fiber downward, are disposed at the side of the laser diode chip in a line, and a receiving photo diode chip for a 1490 nm band wavelength, which detects laser light of a 1490 nm band wavelength, is disposed below the self-standing parallel plate beam splitter for the 1490 nm band wavelength, and a receiving photo diode chip for a 1550 nm band wavelength, which detects laser light of a 1550 nm band wavelength, is disposed below the self-standing parallel plate beam splitter for the 1550 nm band wavelength.

12. The laser diode package structure according to claim 11, wherein a front side incline plane and a back side incline plane of the self-standing parallel plate beam splitter for the 1490 nm band wavelength are alternately coated with a plurality of dielectric thin films having relatively high and low refractive indexes to transmit a 1310 nm band wavelength at the front side incline plane and transmit a 1310 nm band wavelength and reflect a 1490 nm band wavelength at the back side incline plane, and a front side incline plane and a back side incline plane of the self-standing parallel plate beam splitter for the 1550 nm band wavelength are alternately coated with a plurality of dielectric thin films having relatively high and low refractive indexes to transmit a 1310 nm band wavelength and a 1490 nm band wavelength at the front side incline plane and transmit a 1310 nm band wavelength and a 1490 nm band wavelength and reflect a 1550 nm band wavelength at the back side incline plane.

13. The laser diode package structure according to claim 9, wherein a reflective self-standing parallel plate beam splitter for reflecting laser light emitted from the self-standing parallel plate beam splitter at a front side incline plane thereof and forwarding the reflected laser light to the optical fiber, disposed above the reflective self-standing parallel plate beam splitter, and reflecting laser light incident from the optical fiber at the front side incline plane thereof and forwarding the reflected laser light to the self-standing parallel plate beam splitter is further disposed at the side of the self-standing parallel plate beam splitter.

14. A bidirectional-communication triplexer laser diode package structure constructed in a structure in which two TO type optical modules are disposed at a right angle to each other, and a beam splitter is disposed at an intersection point between optical axes of the TO type optical modules, wherein one of the TO type optical modules is a receiving TO type optical module for receiving a 1550 nm wavelength, and the other TO type optical module is a TO type optical module having a bidirectional communication function to transmit laser light of a 1310 nm wavelength and receive laser light of a 1490 nm wavelength as the bidirectional-communication laser diode package according to claim 7, and the beam splitter, disposed at the intersection point between the optical axes of the TO type optical modules, reflects laser light of a 1550 nm wavelength and transmits laser light of a 1490 nm wavelength and laser light of a 1310 nm wavelength.

15. A bidirectional-communication laser diode package structure having a self-standing parallel plate beam splitter according to claim 1, comprising:

a laser diode chip for emitting laser light;

a back side monitoring photo diode chip for detecting the laser light emitted from the back side of the laser diode chip;

a self-standing parallel plate beam splitter having a front side incline plane exhibiting a property to partially reflect and partially transmit laser light emitted from the front side of the laser diode chip;

a narrow line width filter for selecting and transmitting a narrow wavelength region of the laser light transmitted through the self-standing parallel plate beam splitter; and

a front side monitoring photo diode chip for detecting the laser light transmitted through the narrow line width filter, the laser diode chip, the back side monitoring photo diode chip, the self-standing parallel plate beam splitter, the narrow line width filter, and the front side monitoring photo diode chip being arranged in a line to perform a wavelength locking function.

16. The laser diode package structure according to claim 15, wherein the front side incline plane of the self-standing parallel plate beam splitter has a property to transmit laser light emitted from an optical fiber, disposed above the self-standing parallel plate beam splitter, and a receiving photo diode chip for receiving an optical signal emitted from the optical fiber and transmitted through the self-standing parallel plate beam splitter is further disposed below the self-standing parallel plate beam splitter.

17. The laser diode package structure according to claim 15, wherein the back side monitoring photo diode chip, the laser diode chip, the self-standing parallel plate beam splitter, the narrow line width filter, and the front side monitoring photo diode chip are disposed above a thermoelectric device.

18. The laser diode package structure according to claim 7, further comprising:

a preamplifier for amplifying the optical signal received through the receiving photo diode chip.

19. The laser diode package structure according to claim 7, further comprising:

a lens for changing the laser light emitted from the laser diode chip into parallel light.

20. The laser diode package structure according to claim 7, wherein the photo diode chip is installed at the top of a photo diode chip sub mount, and a side plane of the photo diode chip and a space defined between the photo diode chip and the photo diode chip sub mount are filled with a material exhibiting opacity with respect to laser light and an electric insulating property.

21. The laser diode package structure according to claim 7, wherein the laser diode chip is fixedly installed at the top of a second sub mount, and the second sub mount and the self-standing parallel plate beam splitter are fixedly installed at the top of a first sub mount.

22. The laser diode package structure according to claim 7, wherein the laser diode chip is fixedly installed at the top of a second sub mount, the second sub mount and the self-standing parallel plate beam splitter are fixedly installed at the top of a first sub mount, and the receiving photo diode chip is installed inside the first sub mount.

23. The laser diode package structure according to claim 22, wherein the first sub mount has a -shaped groove, in which the receiving photo diode chip is placed.

24. The laser diode package structure according to claim 21, wherein the second sub mount has the same structure as the self-standing parallel plate beam splitter.

25. The communication optical module package structure according to claim 24, wherein the second sub mount is installed at the top of the first sub mount such that the second sub mount is in tight contact with the front side incline plane of the self-standing parallel plate beam splitter.

26. The bidirectional-communication optical module package structure according to claim 7, wherein the receiving photo diode chip is installed at the top of a receiving photo diode chip sub mount, and the receiving photo diode chip is flip-chip bonded to the receiving photo diode chip sub mount.

27. The bidirectional-communication optical module package structure according to claim 7, wherein the package housing is a TO type package housing.

28. The bidirectional-communication optical module package structure according to claim 9, wherein the package housing is a mini-DIL, mini-flat or butterfly package.

29. The laser diode package structure according to claim 7, wherein the minimum height of the optical axis of an optical signal emitted from the optical fiber reaching the front side incline plane of the self-standing parallel plate beam splitter from the bottom plane of the self-standing parallel plate beam splitter is represented by the following Mathematical equation h=t×

cos(45°

−

θ

₂)/cos₂ on the assumption that the refractive index of the air is n₁, the refractive index of the self-standing parallel plate beam splitter is n₂, the incidence angle of the optical axis on the self-standing parallel plate beam splitter in the air is θ

₁ and θ

₂=arc sin(n₂ x sin θ

₁/n₂).