CN102916342A - Vertical-cavity surface-emitting laser device with tunable liquid crystals in inner cavity and manufacturing method thereof - Google Patents

Abstract

The invention discloses a vertical-cavity surface-emitting laser device with tunable liquid crystals in an inner cavity, belonging to the field of semiconductor electronic devices. The laser device comprises three parts, wherein the first part comprises an n-type back electrode (11), a bottom substrate (10), a lower DBR (Distributed Bragg Reflector) (9), an active region (8), a p-type DBR (12) comprising an oxidation limitation layer (7), a p-type injection electrode (6), an ITO (Indium Tin Oxide) layer (14) and an orientation film (3), which are arranged from bottom to top in sequence; the second part comprises a ridge-shaped structure arranged above the oxidation limitation layer (7), symmetric polymer gaskets (5) arranged at the two ridge-shaped ends, and a liquid crystal box which stores liquid crystals (4); the third part comprises a top substrate (1) with a light outlet, an upper DBR (2), the ITO layer (14) and the orientation film (3), which are arranged in sequence; and the third part is placed on the second part in an upside-down manner and supported by the polymer gaskets (5). According to the invention, a tuning voltage is applied to the two ends of the liquid crystal box to cause a change of the refractive index of a liquid crystal layer so as to achieve continuous tuning of laser wavelength. Meanwhile, due to unique anisotropy of the nematic liquid crystals, the laser device can stably output polarized laser.

Description

Inner chamber liquid crystal tunable vertical-cavity surface emitting laser and preparation method thereof

Technical field:

Inner chamber liquid crystal tunable vertical-cavity surface emitting laser belongs to semi-conductor photoelectronic technology and physics of liquid crystals and learns the field, relates to a kind of novel tunable vertical cavity surface emitting laser.

Background technology

Wavelength-tunable vertical-cavity surface emitting laser is the very promising light sources in field such as the dense wave division multipurpose communication technology, detection of gas and spectrum analysis.Inner chamber liquid crystal tunable vertical-cavity surface emitting laser is adding under the tuning voltage effect, utilizes the electrically conerolled birefringence characteristic of liquid crystal layer can realize the wavelength continuous wave output.Because inner chamber liquid crystal tunable vertical-cavity surface emitting laser can reduce cost greatly, improve reliability, following very possible traditional multi-wavelength semiconductor laser array that replaces, and will in fast-developing at present optical interconnection and optical communication network technology, play a significant role.

Wavelength-tunable vertical-cavity surface emitting laser requires the laser stabilization polarization in many applications, so the development of inner chamber liquid crystal tunable vertical-cavity surface emitting laser is significant.The stable output of vertical cavity surface emitting laser realization polarization is main to be adopted as making asymmetric cavity, introducing the modes such as grating and liquid crystal.Germany's Technische University Darmstadt was reported the asymmetric cavity method, the polarization of realizing wavelength tuning by the curvature that changes the upper reflector different crystal orientations is stable, but stress and amount of curvature are wayward because speculum is delayed time outside, are difficult to realize that polarization is stable, unified.The U.S. Chang-Hasnain of Berkeley University seminar has reported that employing high-contrast grating method obtains the polarization tunable vertical-cavity surface emitting laser.Yet because the high-contrast grating is single layer structure, when wet etching discharged grating, the individual layer grating easily was corroded, and has increased the technique manufacture difficulty.France Castany seminar utilizes liquid crystal as the electrooptic modulation layer, realizes the wavelength tuning under the optical pumping, however liquid crystal layer from active area close to, light loss is serious, and the optical pumping mode is unfavorable for commercially producing and practical application.Therefore, we need to invent a kind of new tuning manner and solve above-mentioned technical problem.

Summary of the invention

The object of the present invention is to provide a kind of inner chamber liquid crystal tunable vertical-cavity surface emitting laser, can in wavelength tuning process, realize the stable output of polarization, improve reliability.

Inner chamber liquid crystal tunable vertical-cavity surface emitting laser of the present invention, as shown in Figure 1.Device is divided into three parts: be followed successively by from top to bottom N-shaped backplate 11, base substrate 10, lower DBR9, active area 8, the p-type DBR12 that includes the oxidation limiting layer 7 of light hole, the p-type injecting electrode 6 that light hole is arranged, ITO layer 14, alignment films 3, this is the luminous zone for first, from oxidation limiting layer 7 up structure be ridge; The ridge two ends are the polymer liner 5 of symmetrical structure, consist of liquid crystal cell, and liquid crystal cell stores liquid crystal 4, and this is second portion; Third part is upper reflector, comprises successively, has the top substrate 1 of light hole, upper DBR2, ITO layer 14, alignment films 3; Third part is stood upside down and is placed on the second portion, relies on polymer liner 5 to support.

Structure among the present invention, alignment films 3 obtains by the linear polarized uv polymerization technique;

The present invention also provides a kind of preparation method of inner chamber liquid crystal tunable vertical-cavity surface emitting laser, comprising:

Step 1, at DBR9 under the epitaxial growth successively on the substrate 10, active area 8 includes the p-type DBR12 of the oxidation limiting layer 7 of light hole;

Step 2, photoetching corrosion go out the ridge table top, until expose oxidation limiting layer 7 sidewalls;

Step 3, device oxidation limiting layer 7 is carried out lateral oxidation, form the Injection Current limiting holes;

N-shaped backplate 11 is prepared in step 4, sputter, photoetching, corrosion;

Deposit p-type injecting electrode 6 (6) on step 5, the ridge table top, photoetching, corrosion obtain light hole;

Step 6, deposit growth ITO layer 14;

Step 7, deposit growth orientation film 3 are finished first's preparation;

Step 8, successively epitaxial growth etch stop layer on the substrate 1 13, on DBR2 and ITO14;

Step 9, deposit growth orientation film 3;

Step 10, utilize photoetching and selective wet etching method to be etched into the ridge table top, until expose etch stop layer 13;

Step 11, with substrate thinning, polishing is cleaned, the spin coating photoresist, photoetching obtains light hole, until expose etch stop layer 13;

Step 12, etch away etch stop layer 13 with corrosive liquid, make the upper reflector part;

Step 13, on the luminous zone that step 7 obtains symmetric growth polymer liner (5);

In step 14, the liquid crystal cell that consists of to polymer liner 5, inject liquid crystal 4;

Step 15, employing self-registered technology are carried out bonding, curing with luminous zone and upper reflector, finish element manufacturing.

Adopt self-registered technology that bonding, curing is carried out in luminous zone and upper reflector, finish element manufacturing.

Laser of the present invention can be realized the stable output of polarization in wavelength tuning process, improve reliability.

Description of drawings

Inner chamber liquid crystal tunable vertical-cavity surface emitting laser of the present invention

Fig. 1: inner chamber liquid crystal tunable vertical-cavity surface emitting laser cross section structure schematic diagram of the present invention;

Fig. 2: the ridge table top schematic diagram that inner chamber liquid crystal tunable vertical-cavity surface emitting laser makes by lithography;

Fig. 3: device oxidation limiting layer carries out lateral oxidation and forms Injection Current limiting aperture schematic diagram;

Fig. 4: device back side substrate thinning, preparation bottom electrode device architecture schematic diagram;

Fig. 5: make p-type injecting electrode schematic diagram;

Fig. 6: growth ITO schematic diagram;

Fig. 7: growth orientation membrane structure schematic diagram;

Fig. 8: at upper reflector (third part) epitaxial wafer growth ITO schematic diagram;

Fig. 9: growth orientation membrane structure schematic diagram;

Figure 10: make upper reflector ridge table top schematic diagram by lithography

Figure 11: the top substrate attenuate makes the unthreaded hole schematic diagram by lithography

Figure 12: symmetric growth polymer liner schematic diagram

Figure 13: inject the liquid crystal schematic diagram to liquid crystal cell.

Figure 14: luminous zone (first) and upper reflector (third part) glue and rear device architecture schematic diagram.

Figure 15: device reflectivity curve and quantum well gain spectral.

Among the figure: 1, top substrate 2, upper DBR 3, alignment films 4, liquid crystal 5, polymer liner 6, p-type injecting electrode 7, oxidation limiting layer 8, active area 9, lower DBR 10, base substrate 11, N-shaped backplate 12, p-type DBR 13, etch stop layer 14, ITO layer.

Embodiment

Introduce the preparation method of inner chamber liquid crystal tunable vertical-cavity surface emitting laser below in conjunction with Fig. 2-Figure 14;

33.5 couples of lower DBR9 of epitaxial growth successively on GaAs substrate 10, active area 8 and the p-type DBR12 that includes the oxidation limiting layer 7 of light hole;

Photoetching corrosion goes out the ridge table top of 82 μ m * 82 μ m, until expose oxidation limiting layer 7 sidewalls;

With high temperature oxidation furnace device oxidation limiting layer 7 is carried out lateral oxidation, form the Injection Current limiting holes;

Sputtered with Ti/Au, N-shaped backplate 11 is prepared in photoetching, corrosion;

Deposit p-type injecting electrode 6 on the ridge table top, photoetching, corrosion obtain light hole;

Cross machine deposit growth ITO layer 14 with steaming;

Deposit growth photosensitive polymer alignment films 3 is finished first's preparation;

DBR2 and ITO14 on 13,22.5 pairs of successively epitaxial growth etch stop layer on the GaAs substrate 1;

Cross machine deposit growth orientation film 3 with steaming;

Utilize photoetching and selective wet etching method to be etched into 75 μ m * 75 μ m ridge table tops, until expose etch stop layer 13;

With substrate thinning, polishing is cleaned, and with glue spreader spin coating photoresist, photoetching obtains light hole, until expose etch stop layer 13;

Remove etch stop layer with the etch stop layer corrosive liquid, make the upper reflector part;

Symmetric growth polymer liner 5 on the part of luminous zone;

In the liquid crystal cell that surrounds to polymer liner 5, inject liquid crystal 4;

Adopt self-registered technology that bonding, curing is carried out in luminous zone and upper reflector, finish element manufacturing.

Figure 15 provides reflectivity curve and the quantum well gain spectral of device.As can be seen from the figure, the device excitation wavelength can from the 850nm blue shift to 835nm, can be realized the tuning range of 15nm.When device cavity mould wavelength is 835nm, have another chamber mould wavelength 863nm and produce, but quantum well gain corresponding to 835nm wavelength obviously gains greater than 863nm is corresponding, so only have the lase of 835nm wavelength.

Claims (3)

1. the structure of inner chamber liquid crystal tunable vertical-cavity surface emitting laser, it is characterized in that, device is divided into three parts: be followed successively by from top to bottom N-shaped backplate (11), base substrate (10), lower DBR (9), active area (8), the p-type DBR (12) that includes the oxidation limiting layer (7) of light hole, the p-type injecting electrode (6) that light hole is arranged, ITO layer (14), alignment films (3), this is the luminous zone for first, up is the ridge structure from oxidation limiting layer (7); The ridge two ends are the polymer liner (5) of symmetrical structure, form liquid crystal cell, and liquid crystal cell stores liquid crystal (4), and this is second portion; Third part is upper reflector, comprises successively, and the top substrate (1) of light hole, upper DBR (2), ITO layer (14), alignment films (3) are arranged; Third part is stood upside down and is placed on the second portion, relies on polymer liner (5) to support.

2. inner chamber liquid crystal tunable vertical-cavity surface emitting laser structure as claimed in claim 1 is characterized in that: alignment films obtains by the linear polarized uv polymerization technique.

3. the preparation method of inner chamber liquid crystal tunable vertical-cavity surface emitting laser as claimed in claim 1, it is characterized in that: step is as follows

Step 1, at DBR(9 under the epitaxial growth successively on the substrate (10)), active area (8) includes the p-type DBR(12 of the oxidation limiting layer (7) of light hole);

Step 2, photoetching corrosion go out the ridge table top, until expose oxidation limiting layer (7) sidewall;

Step 3, device oxidation limiting layer (7) is carried out lateral oxidation, form the Injection Current limiting holes;

N-shaped backplate (11) is prepared in step 4, sputter, photoetching, corrosion;

Deposit p-type injecting electrode (6) on step 5, the ridge table top, photoetching, corrosion obtain light hole;

Step 6, deposit growth ITO layer (14);

Step 7, deposit growth orientation film (3) are finished first's preparation;

Step 8, on substrate (1) successively epitaxial growth etch stop layer (13), upper DBR(2) and ITO(14);

Step 9, deposit growth orientation film (3);

Step 10, utilize photoetching and selective wet etching method to be etched into the ridge table top, until expose etch stop layer (13);

Step 11, with substrate thinning, polishing is cleaned, the spin coating photoresist, photoetching obtains light hole, until expose etch stop layer (13);

Step 12, etch away etch stop layer (13) with corrosive liquid, make the upper reflector part;

Step 13, on the luminous zone that step 7 obtains symmetric growth polymer liner (5);

In step 14, the liquid crystal cell that consists of to polymer liner (5), inject liquid crystal (4);

Step 15, employing self-registered technology are carried out bonding, curing with luminous zone and upper reflector, finish element manufacturing.

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