WO2002014230A1

WO2002014230A1 - Flame hydrolysis deposition process for making integrated optical components

Info

Publication number: WO2002014230A1
Application number: PCT/US2001/018542
Authority: WO
Inventors: Heather D. Boek; Nikolaus Boos
Original assignee: Corning Incorporated
Priority date: 2000-08-15
Filing date: 2001-06-06
Publication date: 2002-02-21
Also published as: AU2001268254A1

Abstract

A method for depositing a presintered glass layer (20) rather than fine soot particles on a substrate for use in an integrated optical component. Varying the ratio of the fuel mixture components or fuel rate of the burner (26) (or both) provides control over the microuniformity of the deposited glass layer (20) upon the substrate (22). The presintered glass layer (20) provides a planar optical waveguide with better compositional microuniformity and surface roughness values.

Description

FLAME HYDROLYSIS DEPOSITION PROCESS FOR MAKING INTEGRATED OPTICAL COMPONENTS

CROSS-REFERENCE TO RELATED APPLICATIONS This is a continuation-in-part of the co-pending United States Patent

Application Serial No. 08,988,170 filed on December 10, 1997, which in turn claims priority from provisional application Serial No. 60/032,904 filed on December 16, 1996, each of which is incorporated herein by reference as though fully set forth in all details, and the benefit of priority pursuant to the applicable provisions of 35 USC §119 and § 120 is hereby claimed for any common subject matter disclosed therein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to fabricating integrated optical components, and more particularly to a flame hydrolysis deposition (FHD) process used in manufacturing integrated optical components.

2. Technical Background

Integrated optical components are important to optical networks. An integrated or "planar" optical component as used in this application is typically a substrate with one or more layers of core and cladding glass (or polymeric overclads) deposited thereon. An integrated optical component may be used in the optical path of an entirely-planar optical circuit, or in combination with other optical elements such as fiber waveguides, free-space optics, and so forth. Typical and representative types of integrated optical components include phased-arrays ("phasars") for wavelength- division-multiplexing, optical cross-connect switches, gratings, lenses, and microprisms. The preceding list is illustrative only, and not intended to be all- inclusive. As used herein, the term "planar" identifies a particular class of substrates, components, and fabrication processes as understood by those skilled in the art, and is not intended to refer to a physical shape of the substrate or component.

Several techniques are known for producing integrated optical components for use in optical devices or circuits. One such approach is utilizing a flame hydrolysis deposition (FHD) technique to deposit a core layer of doped silica onto a substrate. In this technique, a flame burner deposits fine glass particles ("soot") on the substrate. A subsequent sintering step vitrifies the fine soot particle layer into a transparent glass layer.

In this approach, somewhat stringy particle aggregates are deposited and stacked upon the substrate, as shown for example in Figure 1. The average particle size is typically in the range of 0.1-0.2 μm, which results in a total surface area of soot deposit on the order of a few square meters. In the subsequent sintering step (which is typically performed in a temperature range from approximately 1000°C - 1400°C), the layer is densified due to viscous flow.

One disadvantage with this approach is that sintering temperatures are typically high enough to induce loss of dopants due to volatilization. For example, the dissociation reaction GeO₂ (s) «-> GeO(g)+ Vτ O₂ is in equilibrium at approximately

1490°C and shifts to the right at higher temperatures. The vapor pressure of the dopant oxides P₂O₅ and B₂O₃ at consolidation temperatures is very high, as may be understood from the vapor pressure curves related to dopant oxides as shown and discussed in U.S. Patent No. 5,503,650. Figures 2a-2d are backscattered electron images taken at various stages of a prior art sintering process for deposition of a fine glass particle layer on a substrate. Figure 2a illustrates the composition microuniformity of the consolidation sintering process of the fine glass particle layer after thirty minutes of consolidation for a section through a thin glass film. Figure 2b is a photograph of the compositional microuniformity of the surface of the thin glass film after thirty minutes of consolidation. The bright areas in Figure 2b correspond to zones enriched with the dopant GeO , while the relatively darker zones are GeO₂ depleted. Figure 2c is a section through the thin glass film after forty-five minutes of consolidation. Figure 2d illustrates composition microuniformity of the surface of thin glass film after forty-five minutes of consolidation. A dopant concentration gradient exists at the free surfaces and pores of the not-yet-fully-densified glass layer, as shown in Figures 2a and 2b. The compositional inhomogeneities remain in the core layer and on its surface even after full densification of the glass as shown in Figures 2c and 2d.

As illustrated by Figures 2a-2d, the prior art approaches suffer from the disadvantage of producing a glass layer composition which is insufficiently uniform on a microscopic scale and therefore gives rise to a non-uniform refractive index when used in an integrated optical component. Moreover, prior art approaches also experience the disadvantage of surface roughness characteristics that result in -undesirable optical propagation loss when used in integrated optical components.

SUMMARY OF THE INVENTION

The present invention overcomes these disadvantages. In accordance with the teachings of the present invention, a presintered glass layer (rather than fine soot particles) is deposited on the substrate. Preferably, the fuel mixture contains oxygen, methane, and an organometallic compound. The fuel may include a dopant to dope the components. Varying the ratio of the fuel mixture components or the fuel rate of the burner (or both) provides control over the microuniformity of the deposited glass layer upon the substrate. The presintered glass layer provides a planar optical waveguide with relatively better compositional microuniformity and surface roughness values. Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or-recognized by practicing the invention as described in the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both of the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview of framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various features and embodiments of the invention, and together with the description serve to explain the principles and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a photograph illustrating a deposition of fine glass particles on a silica substrate according to a prior art approach;

Figures 2a-2d are photographs illustrating composition microuniformity at various stages of the consolidation sintering process of a fine glass particle layer in a prior art approach;

Figure 3 is a side view of the flarrie hydrolysis deposition process of the present invention;

Figure 4 is a backscattered electron image of the surface of a core layer with a fine glass particle deposition and consolidation performed according to a prior art approach;

Figure 5 is a backscattered electron image of the surface of a core layer with a presintered glass layer deposition and consolidation performed according to the teachings of the present invention; Figure 6 includes photographs depicting the topography and a backscattered electron image of a core wafer formed in accordance with a prior art approach;

Figure 7 is a photograph that includes an x-y graph illustrating the composition microuniformity of a core layer that had been processed according to the teachings of the present invention; Figure 8 is a photograph that includes an x-y graph illustrating the composition microuniformity of a core layer that had been processed according to a prior art approach; and

Figure 9 is an x-y graph depicting the mean surface roughness value R_a of flame hydrolysis deposition thin films versus softening point of the glass. DETAILED DESCRIPTION THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts.

Figure 3 depicts an exemplary embodiment of the present invention for depositing a presintered glass layer 20 on a substrate 22. A flame hydrolysis deposition unit 24 feeds a burner 26 with a fuel mixture. Preferably, the fuel mixture contains oxygen, methane, and an organometallic vapor. Varying the ratio of the fuel mixture constituents and/or fuel rate of burner 26 provides control of the density and hence the microuniformity of deposited glass layer 20 upon substrate 22. In the preferred embodiment, the ratio of methane to oxygen is less than or greater than 1:2. Such ratios provide for better microuniformity. Exemplary ratios of methane to oxygen include approximately 1 : 1.9 or 1 :2.1. As an example, substrate 22 is a silica substrate which is rotated in a random manner over flame 28 by connector 30. Connector 30 preferably is coupled to substrate 22 by a suction vacuum. Conditions of the deposition of the presintered glass layer 20 were as follows: a rotation speed of substrate 22 was 0.5 rpm; a moving speed of substrate 22 was 3000 millimeters/minutes; a moving distance of the substrate 22 was 195 millimeters; a speed rate of the fuel mixture into the burner 26 was 32.35 liters per minute.

Methane was added to the fuel mixture at a rate of 11.07 liters per minute. Oxygen was added to the fuel mixture at a rate of 21.28 liters per minute. The temperature of the flame was 1800°C at approximately the location where the substrate touches the flame. The temperature of the substrate was approximately between 750°C - 800°C. Under these conditions, a 6.5 micrometer layer of presintered glass was deposited within 1.5 hours on substrate 22. In this example, a P₂O₅-B₂O₃-GeO₂ doped SiO . thin film was deposited such that presintering of the film occurs substantially concurrently with the consolidation of the film. It should be understood that the present invention is not limited to the aforementioned values, but includes such variations as, but not limited to, ranges as 650°C - 1200°C for substrate temperature and 1600°C -

2500°C for flame temperature.

In a second example which also exemplifies the controlling of the density of the glass layer, conditions of the deposition were as follows: a rotation speed of substrate 22 was 0.64 rpm; a moving speed of substrate 22 was 651 millimeters per minute; a moving distance of substrate 22 was 203 millimeter; a speed rate of the fuel mixture into the burner 26 was 32.4 liters per minute. Methane was added to the fuel mixture at a rate of 10.6 liters per minute. Oxygen was added to the fuel mixture at a rate of 21.78 liters per minute. The temperature of the flame was 1800°C at approximately the location where the substrate touches the flame. The temperature of the substrate was 750°C. Under these conditions, a 6.5 micrometer layer of presintered glass was deposited within 2.2 hours on substrate 22. In this example, a P₂O₅-B₂O₃-GeO doped SiO₂ thin film was also deposited. In these first two examples, an organometallic liquid was added to the fuel mixture at a rate of 0.06 milliliters per minute after vaporization of the organometallic liquid.

A third example exemplifies the controlling of the density of the glass layer as well as the advantage of enhanced macrouniformity across substrate 22. Within the present invention, the term macrouniformity signifies that the deposited glass layer exhibits substantial macrouniformity across the substrate in that the effective index across the substrate is substantially uniform.

Conditions for the third example of the deposition were as follows: a liquid rate of 0.04 millimeters per minute; a rotation speed of substrate 22 was 0.0045 rpm; a moving speed of substrate 22 was 3000 millimeters per minute; a moving distance of substrate 22 was 260 millimeter; a speed rate of the fuel mixture into the burner 26 was

32.35 liters per minute. Methane was added to the fuel mixture at a rate of 11.07 liters per minute. Oxygen was added to the fuel mixture at a rate of 21.28 liters per minute. The temperature of the flame was 1800 °C at approximately the location where the substrate touches the flame. The temperature of the substrate was 750 °C. Under these conditions, a 6.5 micrometer layer of presintered glass was deposited within 4 hours on substrate 22. In this example, a P₂Os-B₂O₃-GeO₂ doped SiO₂ thin film was also deposited.

In this example, the macrouniformity is shown to be enhanced. With respect to macrouniformity, the target σ for thickness variation across substrate 22 of 10.16 centimeters (4 inches) was 0.2 micrometer. The target σ for %Δ across substrate 22 of 10.16 centimeters (4 inches) was 0.02 %Δ, where:

%Δ = relative measure of the -index difference

= 100 * [(index of the glass layer) - (index of the silica)]/(index of the silica) Application of these metrics yields the following macrouniformity results for the present invention in comparison to a previous approach:

As shown by this table, the present invention results in superior macrouniformity results than the previous approach.

For the aforementioned non-limiting examples, the composition of the organometallic liquid is the following: octamethylcyclotetrasiloxane (source of SiO₂); triethylborate (source of B₂O₃); triethylphosphate (source of P₂O₅); and tetraethoxy germane (source of GeO₂).

It is to be understood, however, that the present invention is not limited to these conditions as they are only exemplary conditions under which the present invention can be practiced. The advantages of the present invention are achieved by generally choosing process conditions in which a presintered glass layer (rather than fine soot particles) are deposited on substrate 22. A transparent glass film rather than soot is deposited when the characteristic sintering time (which is a function of the soot particle viscosity and its surface energy) is smaller than the characteristic time for deposition of the soot particles. The parameters which determine the transition between the different morphologies of the deposit (fine glass particles or presintered glass) are typically temperature of the substrate, flame temperature, and flame velocity, and dopant flow rate (i.e., flow rate of the organometallic vapor). The present invention provides for increasing the temperature of the substrate in order to improve microuniformity but not to a point that deforms the substrate. The present invention provides for increasing the flame temperature in order for improving microuniformity. The present invention provides for increasing the flame velocity for improving microuniformity. Such parameter changes increase the temperature of the deposition conditions and thus assist in improving microuniformity. Moreover, the present invention provides for decreasing the dopant flow rate for improving mifcrouniformity.

A presintered glass layer 20 of the present invention exhibits better compositional microuniformity and better surface roughness characteristics (i.e., improved surface smoothness) than planar flame hydrolysis processes that deposit and consolidate layers of fine glass particle layers. The significant improvement in microuniformity and surface roughness correspondingly improves the optical quality of the manufactured component. Moreover, in the case of the deposition of a presintered glass of the present invention, the surface area of the deposit is dramatically reduced which results in suppressing the volatilization of the dopants. Figures 4 and 5 illustrate the advantages of the present invention with respect to volatilization of the dopants. Figure 4 is a backscattered electron image of the surface of a core layer after fine glass particle deposition and consolidation has taken place according to a technique of prior art. Figure 5 is a backscattered electron image of the surface of core layer after a presintered glass layer deposition consolidation has taken place according to the teachings of the present invention. The relatively brighter areas in Figures 4 and 5 depict regions in the core layer that are rich in the dopant GeO₂ while the relatively darker regions indicate regions where the dopant is depleted. Figure 4 which depicts the prior art approach shows much less microuniformity relative to the approach of the present invention that is depicted in Figure 5. Figure 6 illustrates even further the disadvantages of the prior art approach. The compositional non-microuniformity of the prior art as shown in the upper image of Figure 6 relates the different thermal expansion coefficients directly into a fine scale surface roughness which is indicated by the lower image of Figure 6. Once again, the bright regions indicate dopant rich regions, while the darker regions indicate dopant depleted regions. The upper image of Figure 6 depicts the topography of a core layer of the prior art and is measured with a ZYGO interferometric microscope while the lower image depicts a corresponding backscattered electron image of the core layer. A comparison of the upper and lower images illustrates that the "hills" and "valleys" in the core layer correspond to dopant depleted and enriched zones. An exemplary set of corresponding regions has been marked for the upper and lower images by reference numeral 40.

Figure 7 depicts the compositional microuniformity make-up of a core layer produced by the techniques of the present invention. Figure 8 depicts the compositional microuniformity of a core layer produced by a prior art approach.

Graphic representation of these backscattered electron images for Figures 7 and 8 are graphically shown in the upper right hand corner of each figure. The graphs have an abscissa axis in microns and an ordinate axis of weight percentage of a dopant. The top curve in each of the graphs depicts the GeO₂ microuniformity while the second curve from the top in each graph depicts the microuniformity of B O₃, and the bottom curve depicts the microuniformity of P₂Os. The curves in Figure 7 for each of the dopants exhibit significantly less variation across the section of the core layer versus that of the prior art approach as shown in Figure 8.

The following table depicts the statistics associated with each dopant in Figure 7:

The following table depicts the statistics associated with each dopant in Figure

8:

The following table lists the relative variation, i.e. the ratio of the 1 σ value of the dopant contents to the mean dopant contents for each of the oxides P₂O₅, B₂O₃ and GeO as determined from the electron microprobe analysis. Clearly, the relative variation in the present invention's core layers is smaller than in the prior art produced core layers.

In addition to the above advantages including the microuniformity advantage, surface roughness of a thin glass film of the present invention is substantially improved through the presintering of the deposit before or during deposition upon substrate. Planar optical components are usually fabricated either on silica or silicon substrates. Whereas devices on silicon need additional process steps or additional technology, the silicon dioxide integrated optical components manufactured on silicon dioxide substrates can be manufactured with low polarization dependent effects and low warpage of the wafers by a proper choice of the glass composition for matching the thermal expansion coefficients of the substrate, core layer and overclad. Compositions for core layers which are CTE-matched to silicon dioxide substrates have softening points of 1350°C and higher whereas the compositions matched to the silicon substrates can have lower softening points.

Figure 9 depicts the mean surface roughness value R_a of flame hydrolysis deposition thin films versus softening point of the glass. A series of data is shown for layers which result from deposition of fine glass particles and consolidation as produced by the prior art which has a rectangular symbol 60, as well as showing deposition of presintered glass and consolidation of the present invention shown by the diamond symbol 62. A typical target value for surface roughness related to macrouniformity is below 10 nanometers as measured by the WYCO measurement instrument. With respect to microuniformity, the present invention provides for surface roughness values in the range of approximately 0.09 to 0.32 nanometers as measured by the AFM (Atomic Force Measurement) instrument.

In the case of soot particle deposition and consolidation of the prior art, there is a clear increase shown in Figure 9 towards higher undesirable roughness values for glass compositions in the target range with a softening point of greater than 1350°C. Films resulting from presintered glass deposition do not exhibit such a tendency towards a higher undesirable roughness value and consequently a wider range of composition from low to high softening points (greater than 1500°C) can be deposited without a penalty in surface quality. In the range of interest, the surface roughness has been improved by a factor of greater than 10 by depositing and consolidating a presintered glass layer instead of depositing and consolidating a fine glass particle layer.

It will be apparent to those skilled in the art that various modifications and adaptations can be made to the present invention without departing from the spirit and scope of this invention. Thus, it is intended that the present invention covers the modifications and adaptations of this invention, provided that they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A method for manufacturing a waveguide for use in an integrated optical component, the waveguide being fabricated on a substrate, the method comprising the steps of: providing a fuel; providing a flame at least proximate to the substrate, the flame burning the fuel at a fuel rate; depositing a glass layer upon the substrate; and controlling the fuel rate to the flame in order to control microuniformity of the glass layer deposited upon the substrate.

2. The method of claim 1 wherein the glass layer is presintered while depositing the glass layer upon the substrate.

3. The method of claim 1 wherein the glass layer is sintered during the step of depositing the glass layer on the substrate.

4. The method of claim 1 wherein the glass layer is consolidated, and wherein the method further comprises the step of: sintering the glass layer before it is consolidated.

5. The method of claim 1 further comprising the step of: controlling the deposition of the glass layer based upon at least one predetermined parameter, the predetermined parameter being selected from a group consisting of sintering time, flame temperature, flame velocity, substrate temperature, and combinations thereof.

6. The method of claim 5 further comprising the step of: controlling the sintering time such that the sintering time is less than characteristic time for deposition of soot particles upon the substrate.

7. The method of claim 5 further comprising the step of: increasing the flame temperature in order to control microuniformity of the glass layer deposited upon the substrate.

8. The method of claim 5 further comprising the step of: increasing the substrate temperature in order to control microuniformity of the glass layer deposited upon the substrate.

9. The method of claim 5 further comprising the step of: increasing the flame velocity in order to control microuniformity of the glass layer deposited upon the substrate.

10. The method of claim 1 wherein the glass layer is presintered when deposited on the substrate and substantially transparent when deposited on the substrate.

11. The method of claim 1 wherein the glass layer is presintered when deposited on the substrate and substantially translucent when deposited on the substrate.

12. The method of claim 11 wherein the glass layer contains a dopant.

13. The method of claim 12 wherein the dopant includes a component selected from the group consisting of germanium, phosphorus, boron, and combinations thereof.

14. The method of claim 12 wherein the dopant has a temperature at which the dopant undergoes volatilization, the method further comprising the step of: depositing the glass layer upon the substrate at a temperature below the temperature at which the dopant undergoes volatilization.

15. The method of claim 14 further comprising the step of: substantially suppressing the volatilization of the dopant by depositing the glass layer in a presintered state upon the substrate.

16. The method of claim 1 further comprising the step of: depositing the glass layer upon the substrate so that the glass layer exhibits substantial surface smoothness.

17. The method of claim 1 further comprising the step of: depositing the glass layer upon the substrate so that the glass layer exhibits a surface roughness value of less than ten nanometers related to macrouniformity of the deposited glass layer.

18. The method of claim 1 further comprising the step of: depositing the glass layer upon the substrate so that the glass layer exhibits a surface roughness value of less than 0.35 nanometers related to the microuniformity of the deposited glass layer.

19. The method of claim 1 wherein the substrate is selected from a group consisting of silicon or silicon dioxide.

20. The method of claim 1 wherein the fuel is a fuel mixture including constituents selected from a group consisting of oxygen, methane, an organometallic compound, and combinations thereof.

21. The method of claim 20 wherein the fuel mixture defines a ratio of the constituents, and wherein the method further comprises the step of: controlling the ratio of the constituents of the fuel mixture in order to control the microuniformity of the glass layer deposited upon the substrate.

22. The method of claim 21 wherein the glass layer exhibits substantial macrouniformity across the substrate in that the effective refractive index across the waveguide is substantially uniform.

23. The method of claim 1 wherein the deposited glass layer exhibits macrouniformity across the substrate such that the deposited glass layer is less than 0.3 micrometers thickness for one standard deviation across the deposited glass layer.

24. The method of claim 1 wherein the deposited glass layer includes a germanium dopant, the deposited glass layer exhibiting microuniformity across the substrate such that the deposited glass layer has a value less than 0.04 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.

25. The method of claim 1 wherein the deposited glass layer includes a phosphorus dopant, the deposited glass layer exhibiting microuniformity across the substrate such that the deposited glass layer has a value less than 0.04 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.

26. The method of claim 1 wherein the deposited glass layer includes a boron dopant, the deposited glass layer exhibiting microuniformity across the substrate such that the deposited glass layer has a value less than 0.1 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.

27. A method for manufacturing a waveguide for use in an integrated optical component, the method comprising the steps of: providing a substrate; providing a flame at least proximate to the substrate, the flame burning a fuel having a fuel mixture, the fuel mixture defining a ratio of the constituents; depositing a glass layer upon the substrate; and controlling the ratio of the constituents of the fuel mixture in order to control the microuniformity of the glass layer deposited upon the substrate.

28. The method of claim 27 wherein the fuel mixture includes methane and oxygen, said method further comprising the step of: controlling the ratio of the fuel mixture constituents such that the ratio of methane to oxygen is below 1:2.

29. The method of claim 27 wherein the fuel mixture includes methane and oxygen, said method further comprising the step of: controlling the ratio of the fuel mixture constituents such that the ratio of methane to oxygen is above 1:2.

30. The method of claim 27 wherein the glass layer is presintered while depositing the glass layer upon the substrate.

31. The method of claim 27 wherein the glass layer is sintered during the step of depositing the glass layer on the substrate.

32. The method of claim 27 wherein the glass layer is consolidated, and wherein the method further comprises the step of: sintering the glass layer before it is consolidated.

33. The method of claim 27 further comprising the step of: controlling the deposition of the glass layer based upon at least one predetermined parameter, the predetermined parameter being selected from a group consisting of sintering time, flame temperature, flame velocity, substrate temperature, and combinations thereof.

34. The method of claim 27 wherein the glass layer is presintered and substantially transparent when deposited on the substrate.

35. The method of claim 27 wherein the glass layer is presintered and substantially translucent when deposited on the substrate.

36. The method of claim 35 wherein the glass layer contains a dopant.

37. The method of claim 36 wherein the dopant has a temperature at which the dopant undergoes volatilization, the method further comprising the step of: depositing the glass layer upon the substrate at a temperature below the temperature at which the dopant undergoes volatilization.

38. The method of claim 37 further comprising the step of: substantially suppressing the volatilization of the dopant by depositing the glass layer in a presintered state upon the substrate.

39. The method of claim 27 further comprising the step of: depositing the glass layer upon the substrate so that the glass layer exhibits substantial surface smoothness.

40. The method of claim 27 further comprising the step of: depositing the glass layer upon the substrate so that the glass layer exhibits a surface roughness value of less than ten nanometers related to macrouniformity of the deposited glass layer.

41. The method of claim 27 further comprising the step of: depositing the glass layer -upon the substrate so that the glass layer exhibits a surface roughness value of less than 0.35 nanometers related to the microuniformity of the deposited glass layer.

42. The method of claim 27 wherein the glass layer exhibits substantial macrouniformity across the substrate in that the effective refractive index across the waveguide is substantially uniform.

43. The method of claim 27 wherein the deposited glass layer exhibits macrouniformity across the substrate such that the deposited glass layer is less than 0.3 micrometers thickness for one standard deviation across the deposited glass layer.

44. The method of claim 27 wherein the deposited glass layer includes a germanium dopant, the deposited glass layer exhibiting microuniformity across the substrate such that the deposited glass layer has a value less than 0.04 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.

45. The method of claim 27 wherein the deposited glass layer includes a phosphorus dopant, the deposited glass layer exhibiting microμniformity across the substrate such that the deposited glass layer has a value less than 0.04 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.

46. The method of claim 27 wherein the deposited glass layer includes a boron dopant, the deposited glass layer exhibiting microuniformity across the substrate such that the deposited glass layer has a value less than 0.1 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.

47. An optical component comprising at least a portion of the material resulting from a process having the steps of: providing a substrate; providing a flame at least proximate to the substrate, the flame burning a fuel at a fuel rate; depositing a presintered glass layer upon the substrate; and controlling the flame in order to control microuniformity of the glass layer deposited upon the substrate.

48. The optical component of claim 47 wherein the flame burns a fuel at a fuel rate, wherein the process further comprises the step of controlling the fuel rate to the flame in order to control microuniformity of the glass layer deposited upon the substrate.

49. The optical component of claim 47 wherein the flame burns a fuel having a fuel mixture, the fuel mixture defining a ratio of the constituents, the process further comprising the step of controlling the ratio of the constituents of the fuel mixture in order to control the microuniformity of the glass layer deposited upon the substrate.

50. The optical component of claim 47 wherein the glass layer is consolidated, and wherein the process further comprises the step of: sintering the glass layer before it is consolidated.

51. The optical component of claim 47 wherein the process further comprises the step of: controlling the deposition of the glass layer based upon at least one predetermined parameter, the predetermined parameter being selected from a group consisting of sintering time, flame temperature, flame velocity, substrate temperature, and combinations thereof.

52. The optical component claim 47 wherein the glass layer is presintered and substantially transparent when deposited on the substrate.

53. The optical component of claim 47 wherein the glass layer is presintered and substantially translucent when deposited on the substrate.

54. The optical component of claim 53 wherein the glass layer contains a dopant.

55. The optical component of claim 54 wherein the dopant has a temperature at which the dopant undergoes volatilization, the process further comprising the step of: depositing the glass layer upon the substrate at a temperature below the temperature at which the dopant undergoes volatilization.

56. The optical component of claim 55 wherein the process further comprises the step of: substantially suppressing the volatilization of the dopant by depositing the glass layer in a presintered state upon the substrate.

57. The optical component of claim 47 wherein the process further comprises the step of: depositing the glass layer upon the substrate so that the glass layer exhibits substantial surface smoothness.

58. The optical component of claim 47 wherein the process further comprises the step of: depositing the glass layer upon the substrate so that the glass layer exhibits a surface roughness value of less than ten nanometers related to macrouniformity of the deposited glass layer.

59. The optical component of claim 47 wherein the process further comprises the step of: depositing the glass layer upon the substrate so that the glass layer exhibits a surface roughness value of less than 0.35 nanometers related to the microuniformity of the deposited glass layer.

60. The optical component of claim 47 wherein the glass layer exhibits substantial macrouniformity across the substrate in that the effective refractive index across the waveguide is substantially uniform.

61. The optical component of claim 47 wherein the deposited glass layer exhibits macrouniformity across the substrate such that the deposited glass layer is less than 0.3 micrometers thickness for one standard deviation across the deposited glass layer.

62. The optical component of claim 47 wherein the deposited glass layer includes a germanium dopant, the deposited glass layer exhibiting microuniformity across the substrate such that the deposited glass layer has a value less than 0.04 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.

63. The optical component of claim 47 wherein the deposited glass layer includes a phosphorus dopant, the deposited glass layer exhibiting microuniformity across the substrate such that the deposited glass layer has a value less than 0.04 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.

64. The optical component of claim 47 wherein the deposited glass layer includes a boron dopant, the deposited glass layer exhibiting microuniformity across the substrate such that the deposited glass layer has a value less than 0.1 for one standard deviation weight percentage divided by mean weight percentage of the deposited glass layer.