GB2390153A - Measurement of facet reflectivity - Google Patents
Measurement of facet reflectivity Download PDFInfo
- Publication number
- GB2390153A GB2390153A GB0214673A GB0214673A GB2390153A GB 2390153 A GB2390153 A GB 2390153A GB 0214673 A GB0214673 A GB 0214673A GB 0214673 A GB0214673 A GB 0214673A GB 2390153 A GB2390153 A GB 2390153A
- Authority
- GB
- United Kingdom
- Prior art keywords
- facet
- reflectivity
- facets
- transmissivity
- output intensity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
- G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
- G01M11/331—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face by using interferometer
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
- G01M11/31—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter and a light receiver being disposed at the same side of a fibre or waveguide end-face, e.g. reflectometers
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
There is provided a method of measuring the reflectivity or transmissivity of a facet of an optical device. A beam of light (1) is split into a plurality of beams having equal intensities at a known ratio. Each beam is then directed onto a facet (3,4), wherein one of the facets is a reference facet (3) of known reflectivity or transmissivity. The output intensity from the or each of the other facets (4) is measured, and the output intensity from the or each of the other facets is compared with the output intensity from the reference facet (3) to obtain a value for reflectivity or transmissivity of the or each of the other facets (4). The beam is preferably split using a multimode interferometer (MMl).
Description
23901 53
MEASUREMENT OF FACET REFLECTIVITY
Field of the Invention
Low reflectivity facets are important to optical semiconductor devices in reducing backscattering noise and increasing optical coupling efficiency. The performance of such facets needs to be evaluated to enable the facets to be optimized for good performance. It is often desirable to have a simple method to measure the reflectivity of a facet.
10 Background to the Invention
Low reflectivity facets are often measured indirectly from spectral modulation measurements (Patterson B.D., Epler J.E., Graf B., Lehmann H.W. , Sigg H.C., PA Superluminescent Diode at 1.3 urn with Very Low Spectral Modulation", IEEE Joumal of Quantum Electronics, vol. 30 (3), 1994). These methods are, however, 15 complex and involve the fabrication of an active device and require several material parameters, such as optical gain, to be known. Methods that do not require the fabrication of active devices, such as spectrometry, are not easily applied to waveguide facets.
20 Summary of the Invention
According to the present invention, a method of measuring the reflectivity or transmissivity of a facet of an optical device comprises the steps of: splitting a beam of light into a plurality of beams having equal intensities at a known ratio; 25 directing each beam onto a facet, wherein one of the facets is a reference facet of known reflectivity or transmissivity; measuring the output intensity from the or each of the other facets; and, comparing the output intensity from the or each of the other facets with the output intensity from the reference facet to obtain a value for reflectivity or 30 transmissivity of the or each of the other facets.
The present invention measures facet reflectivity by comparing the light from a test facet with a facet of known reflectivity, wherein an optical power splitter is used to split a beam into equal intensity beams which are directed through the test facet and the reference facet. This method of measuring the reflectivity is simple 35 and can be used for measuring not only the reflectivity of any facet but also its transmissivity. Any number of facets can be measured simultaneously, reducing the
need to fabricate numerous test devices. The present invention allows low reflectivity facets to be measured easily in a comparatively short period of time.
Preferably, the beam is split using a multimode interferometer (MMI).
Preferably, the beam is split into a plurality of beams having equal 5 intensities.
In one embodiment, the optical device is a semiconductor device, but the present invention can also be used for measuring the reflectivity or transmissivity of optical fibre facets.
10 Brief Description of the Drawings
Examples of the present invention will now be described, in detail, with reference to the accompanying drawings, in which: Figure 1 illustrates a first embodiment of the present invention; Figure 2 illustrates facet reflectivity; 15 Figure 3 shows the results from a simulation of the propagation of a beam in the embodiment of Figure 1; Figure 4 shows the beam propagation from a curved test facet and a flat reference facet; and, Figure 5 shows an embodiment for measuring reflectivity of facets of optical 20 fibres. Detailed Description
In this method, the reflectivity of a facet is measured using an optical power splitter. The power splitter splits an input beam 2, which can be from either a 25 coherent or incoherent light source, into two or more output beams of equal intensities. Figure 1 shows a one by two optical power splitter consisting of a multi mode interference (MMI) splitter 1, which splits the input light 2 into two beams of equal intensity. One output facet is used as a reference facet 3 with known characteristics. The facet 4 under test is integrated into the other output. The 30 proposed technique does not specifically require an MMI splitter 1 but can use any device, which splits incoming light in a known ratio.
As shown in Figure 2, facet reflectivity refers to the reflectivity at the facet seen by light propagating in the waveguides. R. represents the reflected light from the wave within the waveguide 5 and T. represents the transmitted light.
35 Figure 3 shows the results from a simulation of the propagation of a beam of light in an MMI splitter 1. The simulation was done using the finite-difference time domain (FDTD) method (Yee K.S., "Numerical Solution of Initial Boundary Value
problems involving Maxwell's equations in Isotropic Media", IEEE Trans. on Antennas and Propagation, vol. 14, 1966). The light energy is split equally into two paths, with the upper path leading to a facet 4 under test and the lower arm leading to a reference facet 3. In Figure 4, a curved facet is used as a test facet 4 and a flat 5 facet is used as the reference facet 3. The facet 4 under test and reference facet 3 can be coated, such as with an anti-reflection coating, or uncoated. The light from the test facet 4 is measured using a suitable detector and compared with light from the reference facet 3 to determine not only the reflectivity but also the transmittivity of the test facet 4. The beam characteristics from the test facet 4 can also be 10 determined using a beam profiler.
The proposed technique can be used for simultaneously measuring the reflectivity of a number of facets using a one by n splitter, where (n -1) is the number of facets to be measured and one facet is used as the reference facet.
The power splitter can be fabricated from any waveguiding material, which 15 could consist of a dielectric or quantum well heterostructure, and can either be a ridge, buried or gain guiding scheme, while transversely guided using abnupt or graded index structures.
Figure 5 shows an optical fibre setup to measure the reflectivity of a fibre facet. In this embodiment, a 3-dB splitter/coupler 6 is used to split the beam from a 20 light source 7 into two output fibres 8,9. The output light is detected by a detector or beam profiler 10,11 at the end of each fibre, to measure the output intensity from the reference facet 3 and the test facet 4.
Claims (5)
1. A method of measuring the reflectivity or transmissivity of a facet of an optical device, comprising the steps of: 5 splitting a beam of light into a plurality of beams having equal intensities at a known ratio; directing each beam onto a facet, wherein one of the facets is a reference facet of known reflectivity or transmissivity; measuring the output intensity from the or each of the other facets; and, 10 comparing the output intensity from the or each of the other facets with the output intensity from the reference facet to obtain a value for reflectivity or transmissivity of the or each of the other facets.
2. A method according to claim 1, in which the beam is split using a multimode 15 interferometer (MMI).
3. A method according to claim 1 or 2, in which the beam is split into a plurality of beams having equal intensities.
20
4. A method according to any preceding claim, in which the optical device is a semiconductor device.
5. A method according to any of claims 1 to 3, in which the optical device is an optical fibre.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0214673A GB2390153A (en) | 2002-06-25 | 2002-06-25 | Measurement of facet reflectivity |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0214673A GB2390153A (en) | 2002-06-25 | 2002-06-25 | Measurement of facet reflectivity |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0214673D0 GB0214673D0 (en) | 2002-08-07 |
| GB2390153A true GB2390153A (en) | 2003-12-31 |
Family
ID=9939267
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0214673A Withdrawn GB2390153A (en) | 2002-06-25 | 2002-06-25 | Measurement of facet reflectivity |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2390153A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2180641A (en) * | 1985-09-26 | 1987-04-01 | Era Tech Ltd | Optical fibre end face finish assessment |
| EP0422780A2 (en) * | 1989-09-25 | 1991-04-17 | AT&T Corp. | Methods and apparatus for detecting impurities in semiconductors |
| DE19840725A1 (en) * | 1997-09-01 | 1999-03-18 | Gf Mestechnik Gmbh | Optical interferometer for measuring e.g. semiconductor surface microstructure |
-
2002
- 2002-06-25 GB GB0214673A patent/GB2390153A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2180641A (en) * | 1985-09-26 | 1987-04-01 | Era Tech Ltd | Optical fibre end face finish assessment |
| EP0422780A2 (en) * | 1989-09-25 | 1991-04-17 | AT&T Corp. | Methods and apparatus for detecting impurities in semiconductors |
| DE19840725A1 (en) * | 1997-09-01 | 1999-03-18 | Gf Mestechnik Gmbh | Optical interferometer for measuring e.g. semiconductor surface microstructure |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0214673D0 (en) | 2002-08-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Hotate et al. | Optical coherence domain reflectometry by synthesis of coherence function | |
| JPH04221743A (en) | Fiber optic interferometer sensor | |
| CN107727365B (en) | A kind of system using reflectance spectrum fineness measurement optical waveguide loss | |
| US20140125983A1 (en) | Interferometery on a planar substrate | |
| Wiedmann et al. | A generalized approach to optical low-coherence reflectometry including spectral filtering effects | |
| Salehi et al. | Theoretical and experimental analysis of influence of phase-to-intensity noise conversion in interferometric systems | |
| US20180164214A1 (en) | Detection of Fluid Absorption Spectrum | |
| Chen et al. | Optical waveguide propagation loss measurement using multiple reflections method | |
| US20230019946A1 (en) | Optical device for heterodyne interferometry | |
| RU2721739C1 (en) | Fiber-optic instantaneous frequency measuring system of multiple microwave signals | |
| RU193095U1 (en) | Fiber optic device for measuring instantaneous frequencies of multiple microwave signals | |
| KR100483147B1 (en) | System and method for measuring length of optical fiber | |
| GB2390153A (en) | Measurement of facet reflectivity | |
| AU2016231160A1 (en) | Bidirectional photonic integrated circuit with suppressed reflection | |
| JP2014077712A (en) | Optical resonator measuring method and measuring apparatus | |
| Giuliani et al. | Linewidth, autocorrelation, and cross-correlation measurements of counterpropagating modes in GaAs-AlGaAs semiconductor ring lasers | |
| US10514333B2 (en) | Absorption spectrum detection of a fluid | |
| JP3704031B2 (en) | Waveguide characteristic evaluation equipment | |
| EP4116667A1 (en) | Three- wavelengths interferometric measuring device and method | |
| Rajan et al. | Modeling and analysis of the effect of noise on an edge filter based ratiometric wavelength measurement system | |
| Salehi et al. | Conversion of FM-noise into intensity noise in an interferometric system with RF phase modulation of 1550 nm DFB lasers | |
| Salehi et al. | Interferometric noise of RF phase-modulated noisy light | |
| Rao et al. | Simple method to diagnose the performance of electroabsorption modulators on InP using optical low-coherence reflectometry | |
| CN117470501A (en) | Method and system for testing grating physical parameters of high-precision DFB laser | |
| JPS5837496B2 (en) | Optical fiber length measurement method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |