CN103812572A - Tuning device of optical signal transmitting device for communication - Google Patents

Abstract

The invention provides a tuning device of an optical signal transmitting device. The turning device comprises a laser (1), a spectroscope (2), a variable attenuator (3) and a reflection mirror (4). The outer cavity of the laser is formed by the reflection mirror (4). The turning device is characterized in that the outer cavity is also provided with an optical device (8) with an adjustable optical length, and through adjusting the variable attenuator (3) and the optical device (8) with the adjustable optical length at the same time, the turning output of the optical signal is realized by using a self mixing effect.

Description

The tuner of optical signal launcher for communication

Technical field

The present invention relates to a kind of for communicating by letter with the tuner of optical signal launcher, the particularly device of tunable semiconductor lasers output wavelength.

Technical background

Use up to transmit language, data, image or other information.Mainly refer at present laser communication.The condition of using up (comprising visible ray, invisible light, laser, infrared ray, ultraviolet ray) transmitted signal is: light source, light-sensitive detector and the receiver modulated, and light can be from the medium wherein passing through.Optical communication system can be divided into two classes: a class is called " wireless " optical communication, its light signal by space or atmosphere to distant place radiation; " guided wave " optical communication of another kind of being called, also referred to as " wired " optical communication.The electromagnetic wave that forms light along an affined path or optical transmission line propagate.No matter which class is propagated, if distance is very long between sending and receiving, or transmission medium is very poor, will establish more than one relay station along the line, and signal is received, amplifies by repeater, then forwards.(1) optical communication capacity is large: laser communication can be transmitted 100Wan road TV programme Huo100 No. hundred million phones simultaneously.(2) optical communication quality is high: not only directional performance is good, and can adopt invisible light, is difficult for being intercepted and captured by people strong security.(3) optical communication structure is light: due to laser beam, to distribute angle little, and general antenna diameter only has tens centimetres, and weight only has several kilograms; And similar shock wave antenna weighs tens tons, even hundreds of ton with it.The weakness of optical communication be laser aloft by time, run into water droplet and can be absorbed and weaken, so, in the optical cable that laser communication is preferably made at optical fiber, carry out, to guarantee communication quality.

Along with the expansion of optical communication network transmission capacity, more and more to the demand of number of wavelengths, and the conventional light source that optical communication network is used is at present laser with fixed wavelength, therefore need to mate for each wavelength channel the laser of multiple fixed wave length, so just cause cost rising, complex management and number of devices to increase.Tunable wavelength laser, has not only solved the problems that system faces, and has greatly promoted optical-fiber network efficiency, has also reduced production management cost.Therefore tuning laser output wavelength is a very important problem.

The various Fabry-Perot resonant cavitys of the general employing of semiconductor laser, chamber length, temperature, energy gap, gain, carrier concentration, refractive index etc. all can affect its emission wavelength.Existing semiconductor laser wavelength tuning methods can be divided into:

(1) Current Control Technology

Change semiconductor laser Injection Current and can change its output wavelength, its Tuning Mechanism can be interpreted as: the variation of Injection Current causes that carrier concentration changes, thereby has changed refractive index (or gain coefficient), realizes wavelength tuning.But wavelength is by tuning time, light intensity is also modulated.Be 0.01nm/mA for the typical wavelength-current-modulation of general semiconductor laser rate, (thank to Jianping, Wang Pei etc. and luminous power-current-modulation rate is 0.3mW/mA; The wavelength tuning of semiconductor laser and Wavelength stabilized technology, " quantum electronics report " 2002,19 (2): 97).In changing output wavelength, output intensity also changes thereupon, and this is very disadvantageous to some application.In actual application, also to be furnished with steady light, current stabilization circuit etc., make system more complicated.

(2) temperature control technology

Laser wavelength based on temperature control technology is tuning is to utilize refractive index and the energy gap of temperature ride gain medium to realize.Module is built-in with Fabry-Perot etalon and optical power detector, two thermoelectric refrigerating unit and image intensifer (Wucheng guest, Gu Yuan etc.; Tunable Laser Technology and in dwdm system application [J], " optical communication technique ", 2003, (6): 1-2).The shortcoming of this control technology is that complex structure and broadness of tuning are not wide, generally only has several nm; Tuning stabilization time is long, generally needs several seconds.Along with regulating the rising of temperature, effective output can decline to some extent.

(3) mechanical tuning technology

Adopt and in laser cavity, insert dispersion original paper the laser of different wave length is separated in space, manage to make the light of required frequency in chamber, to form vibration, the light beam of other wavelength because of can not starting of oscillation suppressed fall, thereby realize the wavelength tuning of semiconductor laser.At present, adopt in mechanical tuning, MEMS (MEMS (micro electro mechanical system)) structure be most promising a kind of technology (Zhou Nanquan, Tao Chun rectifies etc.; Achieving Wavelength Tuning of External-cavity Semiconductor Laser through Grating Light Valve research, " laser and infrared ", 2008,38 (2): 115), can obtain tuning laser on a large scale.Current tuning interval is at 0.8nm, but the tuning period that tuned speed generally needs several seconds.

Summary of the invention

The technical problem to be solved in the present invention: overcome the deficiency of existing semiconductor laser wavelength tunable technology, provide a kind of simple in structure, with low cost and semiconductor laser wavelength tuning methods that optical system is easy to adjust.

Technical scheme of the present invention is:

A kind of tuner of optical signal launcher, comprise: laser (1), spectroscope (2), variable attenuation sheet (3), speculum (4), formed the exocoel of described laser by described speculum (4), it is characterized in that: in described exocoel, be also provided with light path adjustable optical device (8), by regulate described variable attenuation sheet (3) and described light path adjustable optical device (8) simultaneously, utilize self-mixing effect to realize the tuning operation of light signal.

Described spectroscope utilization is plated and is established semi-transparent, semi reflective film formation on optical substrate.

Described spectroscope is the Brewster mirror of placing with Brewster angle.

Described light path adjustable optical device is: prism wedge sheet, notch cuttype prismatic lens, undaform prismatic lens, electrooptic crystal or acousto-optic crystal.

Described light path adjustable optical device is placed between laser and spectroscope.

Described light path adjustable optical device is arranged between spectroscope and variable attenuation sheet.

Described tuning process meets equation:

$\mathrm{\Δ\λ}=\mathrm{\λ}-{\mathrm{\λ}}_0=\frac{{\mathrm{C\λ\λ}}_0}{2\mathrm{\πc\τ}}\sin (\frac{2\mathrm{\πc\τ}}{\mathrm{\λ}}+\arctan \mathrm{\α}),$

Wherein λ ₀for initial wavelength, α is linewidth factor, τ be light at exocoel τ two-way time, C is the reference value while regulating the different feedback of variable attenuation sheet ratio, c is the light velocity.

The present invention compared with prior art had advantages of:

(1), compared with Current Control Technology, the power that the present invention suppresses to supervene due to wavelength tuning effectively changes, and realizes wavelength tuning and the metastable object of Output optical power;

(2) compared with temperature control technology, the present invention tests simple in structure, and stable output wavelength is good, and repeatability precision is high;

(3) compared with other mechanical tuning technology, the present invention operates in laser outside, simple, and tuning control is convenient;

(4) in addition, can carry out simple outside repacking to laser with fixed wavelength according to the present invention, make its wavelength adjustable, greatly reduce system modification cost, and can not affect the performance of original laser.

(5) compared with existing self-mixing effect tuner, it is adjusted variable attenuation sheet 3 and light path adjustable optical device 8 simultaneously and realizes tuning to described laser by regulating simultaneously, and the tuned speed of quickening, has expanded tunable scope

Accompanying drawing explanation

Fig. 1 is the method schematic diagram that regulates laser output wavelength based on self-mixing effect of the present invention;

Embodiment

As shown in Figure 1, device of the present invention is made up of laser 1, spectroscope 2, variable attenuation sheet 3, speculum 4, spectrometer 5, detector 6, light power meter 7.Wherein general photodiode or the photomultiplier tube detectors of adopting of detector 6.

Specifically being implemented as follows of the inventive method: as shown in Figure 1, laser 1 adopts continuous semiconductor laser, output wavelength is 1060nm, because it is at invisible wave band, in experimentation, can introduce a road visible ray, as auxiliary optical path, be convenient to subsequent optical path and regulate; , guaranteeing that feedback light intensity can meet experiment required in the situation that, increase spectroscopical transmission ratio as far as possible, make Output optical power large as far as possible, data analysis by experiment, choosing spectroscopical transmission ratio is 60%; Spectroscope 2 can be established semi-transparent semi-reflecting film by plating on glass substrate and realize, and also can adopt the optical base-substrate that Brewster angle is placed to realize.

Incide speculum 4 through the reverberation of spectroscope 2, it is collimated light feedback that accommodation reflex mirror 4 makes feedback light, the reflection ray that is speculum 4 overlaps completely with incident ray, An Yuan road feeds back to laser, otherwise be non-collimated light feedback, being the reflection ray and complete incomplete coincidence of incident ray of speculum 4, there is certain little angle in the feedback light of return laser light device and laser output light; Between spectroscope 2 and speculum 4, insert variable attenuation sheet 3, be used for controlling feedback light intensity.Utilize spectrometer 5 to monitor 4 transmission light wavelengths of speculum; Feedback light is after spectroscope 2, and its transmitted light enters detector 6, so just can calculate feedback light intensity.In the time regulating variable attenuation sheet 3, detector 6 and spectrometer 5 just can be recorded the output wavelength of laser under different feedback light intensity.In order to judge that laser output power is subject to the influence degree of feedback light, utilize light power meter 7 to carry out the power output of detection laser, it is very small that experiment shows that laser output power is subject to feedback light to affect fluctuation.

The initial wavelength X of laser of selecting in experiment ₀=1060nm, linewidth factor α is 6, light is 10ns at exocoel τ two-way time.Feedback ratio rate is defined as 10log (feeding back to laser power/laser output power), regulates variable attenuation sheet 3, is feeding back compared with high light, and when feedback ratio ≈-15dB, C value is about 5600, and above-mentioned parameter is brought into

$\mathrm{\Δ\λ}=\mathrm{\λ}-{\mathrm{\λ}}_0=\frac{{\mathrm{C\λ\λ}}_0}{2\mathrm{\πc\τ}}\sin (\frac{2\mathrm{\πc\τ}}{\mathrm{\λ}}+\arctan \mathrm{\α})$

Equation, can be in the hope of λ=1064nm, actually records laser output spectrum and to calculate acquired results consistent; Reduce gradually feedback light intensity, in the time of feedback ratio ≈-20dB, C value is about 1800, calculates gained wavelength 1060.3nm by formula, and the output of actual measurement laser is frequently consistent with the above results; In the time of feedback ratio ≈-25B, C value is about 960, calculates gained wavelength 1059.4nm by formula, and actual measurement laser output spectrum is consistent with the above results.

In above-mentioned exocoel, arrange in light path adjustable optical device 8(Fig. 1 not shown), described light path adjustable optical device 8 can be prism wedge sheet, notch cuttype prismatic lens, undaform prismatic lens etc., enter the position of light path by adjusting above-mentioned prismatic lens, adjust the optical path length of described exocoel, thereby change light at exocoel τ two-way time; Described light path adjustable optical device can be also electrooptic crystal, and the light path adjustable optical elements that acousto-optic crystal etc. are conventional changes the optical path length of whole exocoel by adjusting the optical path length of above-mentioned crystal, thereby changes τ two-way time of exocoel.

Above-mentioned light path adjustable optical device 8 can be arranged on any position in described exocoel, for example: and between laser 1 and spectroscope 2, or spectroscope 2 and variable attenuation sheet 3, or between variable attenuation sheet 3 and speculum 4.

From above-mentioned formula, be not difficult to find out by adjusting exocoel two-way time τ and C value all can realize the tuning of laser, therefore, realize tuning to described laser by adjust variable attenuation sheet 3 and light path adjustable optical device 8 simultaneously in the present invention.

Compared with existing tuning manner, realize tuning to described laser by adjust variable attenuation sheet 3 and light path adjustable optical device 8 simultaneously in the present invention, the tuned speed of quickening, has expanded tunable scope.

Variable attenuation sheet is adjusted to diverse location x _ncorresponding certain laser output wavelength λ _n, feed back ratio and laser output wavelength corresponding (x one by one _n→ λ _n) afterwards, the detector 6 shown in Fig. 1, light power meter 7 and spectrometer 5 all can omit.Only needing accommodation reflex mirror 4 to make feedback light is collimated light feedback, rotates variable attenuation sheet 3 to diverse location x _n, can reach the object of tuning laser output wavelength.Can find out that laser wavelength tuning device is simple in structure, easy to adjust.

In such scheme, employing be that variable attenuation sheet changes feedback light intensity.Replace variable attenuation sheet 3 by iris diaphgram, can reach equally the object that changes feedback light intensity, the clear aperature of iris diaphgram is less, its luminous power transmissivity is lower, otherwise luminous power transmissivity is higher, so just can realize clear aperature corresponding no feedback light intensity, the i.e. corresponding different output wavelength of different sizes.Equally, in experiment, laser output light used is linearly polarized light, changing variable attenuation sheet 3 into a linear polarizer also can accomplish the end in view, if the polarization direction of linear polarizer is parallel with laser output light polarization direction, the transmissivity maximum (be feedback light intensity maximum) of polarizer to laser, if the polarization direction of linear polarizer is vertical with laser output light polarization direction, polarizer is to its transmissivity minimum (being that feedback light intensity is about zero), therefore rotational line polarizer, change the polarization direction of linear polarizer and the angle of laser output light polarization direction, just can realize the object that changes feedback light intensity, thereby tuning laser output wavelength.Above method is all under collimated light feedback, change feedback light intensity by all kinds of optical elements, if utilize non-collimated light feedback characteristics to regulate feedback light intensity, in light path, do not need to add variable attenuation sheet (iris diaphgram/linear polarizer) 3, only need the inclination angle of accommodation reflex mirror 4 can realize the adjusting of feedback light intensity, its principle is: control by the inclination angle that changes feedback light the light intensity ratio that enters laser, the less feedback intensity of angle of the feedback light of return laser light device and laser output light is larger, therefore the inclination angle of accommodation reflex mirror 4 gets final product the object of experiment control feedback light intensity, test laser output wavelength tuning.

In a word, the present invention proposes the new method of tuning laser output wavelength, can effectively avoid the larger variation of power supervened due to wavelength tuning, realize wavelength tuning and the metastable object of Output optical power.In addition, the present invention can be applied to laser with fixed wavelength is carried out to outside repacking, makes its wavelength adjustable, simple, greatly reduces system modification cost.

Claims (7)

1. the tuner of an optical signal launcher, comprise: laser (1), spectroscope (2), variable attenuation sheet (3), speculum (4), formed the exocoel of described laser by described speculum (4), it is characterized in that: in described exocoel, be also provided with light path adjustable optical device (8), by regulate described variable attenuation sheet (3) and described light path adjustable optical device (8) simultaneously, utilize self-mixing effect to realize the tuning operation of light signal.

2. tuner as claimed in claim 1, described spectroscope utilization is plated and is established semi-transparent, semi reflective film formation on optical substrate.

3. tuner as claimed in claim 1, described spectroscope is the Brewster mirror of placing with Brewster angle.

4. tuner as claimed in claim 1, described light path adjustable optical device is: prism wedge sheet, notch cuttype prismatic lens, undaform prismatic lens, electrooptic crystal or acousto-optic crystal.

5. tuner as claimed in claim 1, described light path adjustable optical device is placed between laser and spectroscope.

6. tuner as claimed in claim 1, described light path adjustable optical device is arranged between spectroscope and variable attenuation sheet.

7. tuner as claimed in claim 1, described tuning process meets equation:

$\mathrm{\Δ\λ}=\mathrm{\λ}-{\mathrm{\λ}}_0=\frac{\mathrm{C\λ}{\mathrm{\λ}}_0}{2\mathrm{\πc\τ}}\sin (\frac{2\mathrm{\πc\τ}}{\mathrm{\λ}}+\arctan \mathrm{\α}),$

Wherein λ ₀for initial wavelength, α is linewidth factor, τ be light at exocoel τ two-way time, C is the reference value while regulating the different feedback of variable attenuation sheet ratio, c is the light velocity.

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