CN101517938A

CN101517938A - Optical modulator

Info

Publication number: CN101517938A
Application number: CNA2007800345537A
Authority: CN
Inventors: C·R·德尔; P·J·温策尔
Original assignee: Lucent Technologies Inc
Current assignee: Nokia of America Corp
Priority date: 2006-09-20
Filing date: 2007-09-14
Publication date: 2009-08-26

Abstract

A high-speed optical modulator constructed from a number of lower speed intensity modulators integrated onto a single optical chip, includes a pulse generator and an interferometer, wherein the interferometer including an input coupler, waveguide arms of N and an output coupler. Each waveguide arm has a path length difference of 1/P between a neighboring arm, wherein the P represents the bit rate of an output signal, and each arm is provided with an intensity modulator and a phase shifter running with a speed of P/N bit/s.

Description

Optical modulator

The cross reference of related application

The sequence number that the application requires on September 20th, 2006 to submit to is the priority of 60/845,973 U.S. Provisional Patent Application, and its all files content just is attached to herein by reference as set forth in detail in this article.

Technical field

The present invention relates generally to optical communication field and especially relate to high-speed optical modulator.

Background technology

In the trial that realizes the high-speed wideband optical communication, optical modulator is placed high hopes.

Summary of the invention

Principle according to the present invention is improved prior art, and high-speed optical modulator can be constructed by a plurality of intensity modulators than low speed (intensity modulator) thus.

According to an aspect of the present invention, modulator is constructed from integrated planar light wave circuit (integratedplanar lightwave circuit), comprises pulse generator (pulse carver), interferometer (interferometer) and a plurality of intensity modulator and places the interior phase shifter (phase shifter) of interferometer arm.

According to another aspect of the present invention, pulse generator receives the continuous wavelength light signal enter and produces light pulse with the data transfer rate of P/N, and wherein P is a desired high speed data rate and N is an integer.Light output from pulse generator is introduced in the arm of interferometer.Thereby the phase shifter in regulating every one arm just generates into non-return-to-zero (non-return-to-zero) output light signal during from signal homophase (in phase) addition of all arms.

Description of drawings

Can realize understanding more comprehensively of the present invention with reference to the accompanying drawings, wherein:

Fig. 1 is the schematic diagram according to high-speed optical modulator of the present invention; And

Fig. 2 is the schematic diagram according to the selected embodiment of optical modulator of the present invention.

Embodiment

Hereinafter only illustrated principle of the present invention.Therefore should be understood that those skilled in the art can design various distortion,, comprised principle of the present invention and comprise within the spirit and scope of the present invention though described distortion is not explained clearly in the text or illustrated.

And, all examples of this paper narration and conditional statement mainly only are used for aims of education and at length understand principle of the present invention and the artificial thought that promotes that prior art is made contributions of invention to help the reader, and the present invention constructs to being not limited to the example and the condition of the specific narration of this class.

In addition, all statements and the concrete example wherein of principle of the present invention, feature and the embodiment of this paper narration are in order to comprise the equivalent of its 26S Proteasome Structure and Function.In addition, this paper is intended that this equivalent and had not only comprised existing known equivalent but also be included in the equivalent of exploitation in the future, no matter i.e. structure is carried out any element of being developed of identical function.

Therefore, for example, the diagrammatic sketch that those skilled in the art will recognize that this paper represents to comprise the concept map of the illustrative structures of the principle of the invention.

With reference to figure 1, there is shown exemplary configuration earlier according to the high-speed modulator 100 of training centre structure of the present invention.More specifically, high-speed modulator 100 is depicted as and is integrated on the single semiconductor chip 110, described semiconductor chip 110 comprises pulse generator 120 and interferometer structure 127, described interferometer structure 127 have input coupler 130 and by a plurality of different length waveguide 135[1] ... 135[N] output coupler 150 that connects mutually, wherein each waveguide comprises intensity modulator 140[1] ... 140[N] and phase shifter 145[1] ... 145[N].Intensity modulator 140[1 advantageously] ... 140[N] can be that (electroabsorptionmodulator, EAM), and whole interferometer structure can use common material and step (LiNbO for example to electricity absorption modulator ₃) construct.

Operationally, outside continuous wavelength (CW) light source 117 (for example laser) are used to generate CW light, this CW light is introduced in the modulator chip 110, and receives described CW light by pulse generator 120 in described modulator chip 110, and described pulse generator 120 itself can comprise EAM.To understand easily that as those skilled in the art CW light source 117 there is no need in the outside of modulator chip 110, and can be easily on miscellaneous part is integrated in chip 110.Yet wherein preferably, CW light source 117 is not integrated on the chip 110, is preferably by its edge that receives the chip of CW light and is provided with antireflective coating 115 to promote that the CW that is generated is optically coupled into chip 110.

When CW light was received by pulse generator 120, light pulse sequence produced and is directed to by waveguide 125 input coupler 130 of interferometer structure 127.As discussed previously, pulse generator 120 can advantageously be constructed by EAM, and those skilled in the art will understand easily that described EAM can be easy to make, and can lack very much and demonstrate very high bandwidth.Electricity absorption modulator can be advantageously with very high speed operation and even can integrate with previous described laser c W light source.

Light pulse by pulse generator 120 output is introduced in the interferometer 127, and---just as previously noted---described interferometer 127 comprises input coupler 130, by a plurality of different length waveguide 135[1] ... 135[N] output coupler 150 that light connects, each described waveguide comprises intensity modulator 140[1] ... 140[N] and phase shifter 145[1] ... 145[N].Thereby adjust phase shifter and pass (traverse) every one arm 135[1] ... 135[N] signal homophase addition when the effect by output coupler 150 reconfigures, and subsequently from the edge of chip 110 by waveguide 153 outputs, the edge of described chip 110 is---similar with input---to be enclosed with antireflective coating 155.

Just as previously noted, every one arm 135[1 of interferometer 127] ... 135[N] different paths arranged.Basically (in time) equals path length difference between the arm of 1/P distance and determined by the desired output data rate of modulator 100, and wherein to be desired high speed data rate and pulse generator 120 produce pulse with the speed of P/N to P from the CW light that enters.Single intensity modulator 140[1] ... 140[N] with the operation of the data transfer rate of P/N.In order to generate non-return-to-zero (NRZ) output signal, regulate phase shifter 145[1] ... 145[N], thereby make from all arm 135[1] ... 135[N] the addition of signal homophase.

In this, it will be appreciated by those skilled in the art that and showing that the structure shown in Fig. 1 of the principle of the invention can extend to the multiplexing of any amount of individual traffic.For example, single waveguide arm 135[1] ... 135[N] quantity can be in the nature of things and amplitude modulator 140[1] ... 140[N] and phase shifter 145[1] ... 145[N] respective numbers increase together.

Go to Fig. 2 now, Fig. 2 shows the alternative of the high-speed modulator 200 of constructed in accordance with the principles.As shown in Figure 2, thus this device adopted entire length that reflection geometry advantageously makes integrated chip 210 than before the device shown in Fig. 1 little a lot.More specifically, this reflection configuration makes the single different length waveguide arm 235[1 that comprises interferometer structure] ... 235[N] shortening (shortened) fully from configuration before.

As shown in Figure 2, CW light 217 enters integrated chip 210 and is received by pulse generator 220.Preferably, as front embodiment, the edge of integrated chip is enclosed with antireflective coating 215 and pulse generator 220 can easily be made by EAM.

The pulse of the light that is generated by pulse generator 220 is introduced into and comprises I/O coupler 230 and a plurality of different length waveguide 235[1] ... 235[N] the reflection interferometer structure in, each described waveguide has phase shifter 245[1] ... 245[N] and intensity modulator 240[1] ... 240[N].

As shown in Figure 2, thereby the edge of chip 210 is enclosed with strong reflection coating 255 and enters I/O coupler 230 and pass waveguide arm 235[1] ... 235[N] light by 255 reflections of strong emission layer, entered output waveguide 253 thereby described light substantially oppositely and subsequently draws back by waveguide arm and coupler 230, its place is stated light and is left modulator 200.

The path length difference that it will be appreciated by one of skill in the art that this reflection configuration requires path (time) difference of 1/2P, wherein intensity modulator 240[1] ... 240[N] with P/N bps work.Because intensity modulator 240[1 in an exemplary embodiments] ... 240[N] preferentially by the EAM device configuration, so those devices only need before shown in those similar devices length 1/2.Therefore, the entire length of device is greatly shortened.

Operationally, be the waveguide arm of N if expectation represents the signal of (exhit) P bps and adopts quantity, CW light is introduced into chip 210 or alternatively generates (not shown) by laser on the sheet so.EAM pulse generator 220 converts CW light the pulse of P/N GHz place to, and wherein Zhuan Zhi duty ratio is preferably 1/N.If N=2, coupler can advantageously be a directional coupler.Greater than 2, can advantageously use known star-type coupler for N.Alternatively, can use coupler tree (a tree ofcouplers) according to the customized configuration that is adopted.No matter adopt which kind of coupler configuration, the path length difference of adjacent waveguide arm will be 1/P (is 1/2P for reflection setting).Every one arm route optimization ground comprises static phase shifter, is used for controlling the relative phase of path light signal.If phase control signal is a homophase when reorganization, the output signal that is produced is the NRZ signal so.If they can produce the CSRZ signal so with combination of 180 phase differences and N=2.

In this, though we have used some specific examples to discuss and describe the present invention, it will be appreciated by one of skill in the art that our instruction is not so limited to.Therefore, the present invention should only be limited in the scope of this claim of enclosing.

Claims

1. optical modulator that is used to generate P bps light signal comprises:

Pulse generator, described pulse generator are used for generating light pulse sequence from the continuous wavelength light signal; With

Interferometer, described interferometer are used for producing the more light pulse sequence of high frequency from described light pulse sequence, and described interferometer comprises:

Input coupler;

Output coupler; With

Quantity is the fiber waveguide arm of N, described fiber waveguide arm is connected to described output coupler with described input coupler, in the wherein said waveguide arm each shows the path length difference with adjacent waveguide arm 1/P, and each bar in the described N bar arm all has the intensity modulator that works in P/N bps and is used to regulate the phase shifter of the phase place of the light signal that passes described arm;

Wherein, described phase shifter is conditioned, thus feasible relative phase homophase addition of passing the light signal of described arm by the effect of described output coupler.

2. optical modulator according to claim 1, wherein, described phase shifter is conditioned, thereby makes the relative phase of the light signal pass described arm corresponding to longer in succession arm and the out-phase addition, generates carrier suppressed (CSRZ) signal that makes zero thus.

3. optical modulator according to claim 1, wherein, described interferometer is a reflection configuration, and in the described waveguide arm each shows the path length difference of 1/2P.

4. optical modulator according to claim 2, wherein, described interferometer is a reflection configuration, and in the described waveguide arm each shows the path length difference of 1/2P.

5. optical modulator according to claim 1, wherein, single coupler plays input coupler and output coupler, and the edge of the integrated chip thereon of described modulator comprises the strong reflection coating in the edge of the intensity modulator with described quantity.

6. optical modulator according to claim 1, wherein, described pulse generator comprises electricity absorption modulator.

7. optical modulator according to claim 1, wherein, the intensity modulator of described quantity comprises electricity absorption modulator.

8. optical modulator according to claim 1 also comprises the continuous wavelength laser.

9. optical modulator according to claim 2 also comprises the continuous wavelength laser.