CN112600071A

CN112600071A - Double-kappa distributed Bragg reflector laser

Info

Publication number: CN112600071A
Application number: CN202011071998.6A
Authority: CN
Inventors: 松井康浩
Original assignee: II VI Delaware Inc
Current assignee: II VI Delaware Inc
Priority date: 2019-10-01
Filing date: 2020-10-09
Publication date: 2021-04-02
Also published as: CN112600072A

Abstract

A dual-kappa Distributed Bragg Reflector (DBR) laser is provided. A double-kappa DBR laser includes an active region, a high reflector, a first DBR section and a second DBR section. A highly reflective mirror is coupled to the rear of the active region. The first DBR section is coupled to the front portion of the active region, the first DBR section having a first DBR grating having a first kappa 1. The second DBR section is coupled to the front portion of the first DBR section such that the first DBR section is located between the active region and the second DBR section. The second DBR section has a second DBR grating having a second kappa 2 that is smaller than the first kappa 1. The dual-kappa DBR laser is configured to operate in a lasing mode and has a DBR reflection profile that includes DBR reflection peaks. The lasing mode is aligned to the long wavelength edge of the DBR reflection peak.

Description

Double-kappa distributed Bragg reflector laser

CROSS-APPLICATION OF RELATED APPLICATIONS

This application claims benefit and priority from U.S. provisional application No. 62/908,990 filed on day 1, 10, 2019 and U.S. provisional application No. 62/938,151 filed on day 20, 11, 2019. Application 62/908,990 and application 62/938,151 are both incorporated herein by reference.

Technical Field

Embodiments discussed herein relate to a double kappa (kappa) Distributed Bragg Reflector (DBR) laser.

Background

Unless otherwise indicated herein, the materials described herein are not prior art to the claims of this application and are not admitted to be prior art by inclusion in this section.

Lasers are useful in many applications. For example, lasers may be used in optical communications to transmit digital data across a fiber optic network. The laser may be modulated by a modulation signal, such as an electronic digital signal, to produce an optical signal that is transmitted over the fiber optic cable. Photosensitive devices such as photodiodes are used to convert optical signals into electrical digital signals that are transmitted over fiber optic networks. Such fiber optic networks enable modern computing devices to communicate at high speeds and over long distances.

In various industries, the bit rate of data transmission per channel has exceeded 100 gigabits per second (Gb/s), establishing transmitter performance in excess of 60 gigahertz (GHz) Bandwidth (BW) as an industry goal for the 100Gb/s non-return-to-zero (NRZ) format. Although some electroabsorption modulators have demonstrated the ability to approach 60GHz BW, the BW of Directly Modulated Lasers (DMLs), such as directly modulated Distributed Feedback (DFB) lasers, has lagged behind by about 30 GHz.

The subject matter claimed herein is not limited to implementations that solve any disadvantages or implementations that operate only in environments such as those described above. In contrast, this background is provided merely to illustrate one example technology area in which some implementations described herein may be practiced.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential characteristics of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

Some example embodiments described herein relate generally to a dual-kappa distributed bragg reflector laser.

In an example embodiment, a dual-kappa distributed bragg reflector laser includes a fabry-perot (FP) cavity including a High Reflection (HR) mirror, a first distributed bragg reflector region, and an active region. The active region is located between the high reflector and the first distributed Bragg reflector region. The first distributed bragg reflector region includes a first distributed bragg reflector grating having a length L1 in a range of 10 microns to 30 microns and a first kappa 1.κ 1L1 ranges from 0.5 to 1.0. The dual-kappa distributed bragg reflector laser further includes a second distributed bragg reflector region coupled to the fabry-perot cavity. The second distributed bragg reflector region includes a second distributed bragg reflector grating having a second kappa 2 that is smaller than the first kappa 1 of the first distributed bragg reflector region.

In another example embodiment, a dual-kappa distributed bragg reflector laser includes an active region, a high reflector, a first distributed bragg reflector region, and a second distributed bragg reflector region. A highly reflective mirror is coupled to the rear of the active region. The first distributed bragg reflector region is coupled to a front portion of the active region and has a first distributed bragg reflector grating having a first kappa 1. The second distributed bragg reflector region is coupled to a front portion of the first distributed bragg reflector region such that the first distributed bragg reflector region is located between the active region and the second distributed bragg reflector region. The second distributed bragg reflector region has a second distributed bragg reflector grating having a second kappa 2 that is smaller than the first kappa 1. A dual-kappa distributed bragg reflector laser is configured to operate in a lasing mode and has a distributed bragg reflector reflection curve including a distributed bragg reflector reflection peak. The lasing mode is aligned to the long wavelength edge of the distributed bragg reflector reflection peak.

Drawings

To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 illustrates an exemplary modulation spectrum of an active region of a DBR laser relative to a DBR reflection profile of the DBR region of the DBR laser;

FIG. 2 shows exemplary lasing and side modes of a laser utilizing photon-photon resonance (PPR);

fig. 3A shows an exemplary dual-kappa DBR laser;

FIG. 3B shows various reflection curves associated with the dual-kappa DBR laser of FIG. 3A;

fig. 3C shows the distribution of reactive photons during lasing in three different example lasers including the dual-kappa DBR laser of fig. 3A;

FIG. 3D shows the modulation spectrum and various S21 responses of the dual-Kappa DBR laser of FIG. 3A;

FIG. 4 shows an example split contact DR laser;

fig. 5 shows another example dual-kappa DBR laser; and

figure 6 shows the modulation response and PPR tunability of the split-contact DR laser of figure 4,

all of the figures are arranged in accordance with at least one embodiment described herein.

Detailed Description

This application is related to U.S. patent No. 10,063,032, published on 8/28/2018, and incorporated herein by reference.

Uncooled 53Gbaud PAM4(100Gb) DBR lasers require a sufficient gain length (about 100 microns) to improve high temperature performance. However, it is difficult to achieve both good side-mode suppression ratio (SMSR) and high speed using conventional DBR lasers with uniform grating designs. Some embodiments herein include a dual-kappa DBR laser that achieves both good side-mode suppression ratio and high-speed operation.

Various aspects of example embodiments of the invention will now be described with reference to the drawings. It is to be understood that the drawings are diagrammatic and schematic representations of such example embodiments, and are not limiting of the present invention, nor are they necessarily drawn to scale.

Fig. 1 illustrates an example modulation spectrum 102 of an active region of a DBR laser relative to a DBR reflection profile 104 of a DBR section of the DBR laser, arranged in accordance with at least one embodiment described herein. As shown, the primary lasing mode 106 of the modulation spectrum 102 is aligned to the long wavelength edge 108 of the DBR reflection peak 110 of the DBR reflection curve 104. Thus, lasing of the active region occurs at frequencies (or wavelengths) at the long wavelength edge of the DBR stop band.

When a DBR laser is modulated (e.g., by modulation of the active region), the lasing frequency varies toward shorter wavelengths as the modulation changes from a bias of 0 bits to a bias of 1 bits, and toward longer wavelengths as the modulation changes from a bias of 1 bit to a bias of 0 bits, due to frequency chirp (chirp). In fig. 1, the frequency/wavelength of the main lasing mode 106 for each of the 1 and 0 bits is represented by the respective vertical dashed line labeled 1 or 0, respectively.

As the primary lasing mode 106 moves up and down the long wavelength edge of the reflection curve 104, the frequency chirp caused by the modulation results in a change in reflection. In particular, when the modulation changes from a bias of 0 bits to a bias of 1 bits, the wavelength of the main lasing mode 106 moves towards shorter wavelengths, resulting in increased reflection and thus lower cavity loss. When the modulation changes from a bias of 1 bit to a bias of 0 bit, the wavelength of the main lasing mode 106 moves towards longer wavelengths, resulting in reduced reflection and thus higher cavity loss. In fig. 1, the reflectivity of the DBR region of the DBR laser at the wavelengths corresponding to each of the 1 and 0 bits is represented by the respective horizontal dashed lines labeled 1 or 0, respectively.

In more detail, the rapid current modulation of the active region of the DBR laser causes carrier density variations in the DBR laser. This causes not only optical gain fluctuations but also index fluctuations due to the so-called alpha parameter of the material. These gain and refractive index fluctuations in turn cause intensity and frequency fluctuations, respectively, in the laser light. The relative amount of frequency modulation compared to the intensity modulation of a DBR laser is described by the chirp factor, also known as the alpha parameter or linewidth enhancement factor of the structure. When the DBR laser is detuned such that the lasing mode 106 is located at the long wavelength edge 108 of the DBR reflection peak 110, the refractive index modulation causes modulation of the cavity loss, which decreases or increases the effective (net gain) modulation of the DBR laser. Thus, the laser chirp is converted into an effective enhancement of the differential gain and thus the speed of the DBR laser is increased. Detuned loading effects include effects that occur under modulation when the lasing mode 106 is aligned to the long wavelength edge 108 of the DBR reflective peaks 108, which may include one or more of effective enhancement of differential gain, increased speed, and increased bandwidth.

The slope of the long wavelength edge 108 may determine the magnitude of the detuned loading effect. In general, the detuned loading effect may be more pronounced for steeper slopes. The slope of the long wavelength edge 108 and the width of the DBR stop band may be determined by the length and/or kappa of the DBR grating in the DBR section. In general, for example, a longer length of the DBR section may result in a steeper long wavelength edge 108 and a narrower DBR stop band. In addition, the narrower the DBR stop band, the better the side mode suppression ratio.

However, in typical DBR lasers, the construction of a DBR grating with a steep long wavelength edge 108 and a narrow DBR stop band enables "reactive photons" (also referred to as "confined photons") to penetrate relatively deep into the DBR grating. The reactive photons within the active region may contribute to high speed modulation, while the reactive photons outside the active region do not. In this way, high speed modulation may be improved by improved longitudinal confinement (e.g., shallow penetration) of the reactive photons relative to the DBR grating.

Embodiments described herein may include a DBR laser having a High Reflection (HR) mirror, an active region, and first and second DBR sections, each of the first and second DBR sections having a corresponding first or second DBR grating having a different corresponding first or second kappa. A DBR laser that includes two different DBR gratings with different kappa may be referred to herein as a dual kappa DBR laser. The active region may be located between the high reflector and the first DBR section, the above components forming a fabry-perot (FP) cavity. The second DBR section may be coupled to the first DBR section. The first DBR section may be relatively short and the first kappa section may be relatively strong. The second DBR section may be relatively long and the second kappa section may be relatively weak. The reflection curve of the first DBR section may have a wide DBR reflection peak with a relatively low maximum. The reflection curve of the second DBR may have a relatively narrow DBR reflection peak having a relatively high maximum and a relatively steep slope at the long wavelength edge. Thus, the double kappa DBR may generally have both a relatively high side mode suppression ratio and a relatively shallow penetration depth for high speed operation.

Embodiments described herein may additionally utilize the photon-photon resonance (PPR) effect to improve performance. When a DML such as a DFB laser or DBR laser is modulated, the modulation sidebands broaden the spectrum of the DML around the main lasing mode. If a side mode of the laser cavity is present within the modulation spectrum, such a side band may couple into the side mode and be resonantly amplified. This is depicted in fig. 2. This effect is called the PPR effect, and can enhance the modulation response around a frequency corresponding to the frequency difference between the main mode and the side mode. The frequency separation between the lasing mode and the PPR mode may be referred to as the PPR frequency. Embodiments described herein may have a PPR frequency in a range from 20GHz to 80GHz or other suitable PPR frequencies.

Fig. 3A illustrates an example dual-kappa DBR laser 300 arranged in accordance with at least one embodiment described herein. As shown, the dual-kappa DBR laser 300 includes an inactive region 302 and an active region 304. The passive region 302 may have a length in a range from 120 microns to 250 microns or more. The active region 304 may have a length in a range from 50 microns to 150 microns.

The passive region 302 may include a first DBR section 306 and a second DBR section 308. The first DBR section 306 may be coupled to the front portion 307 of the active region 304. The second DBR section 308 may be coupled to the front 309 of the first DBR section 306.

The first DBR section 306 may include a first DBR grating 310 having a first kappa. The first DBR section 306 may be relatively short, such as 30 microns or less, or in the range from 10 microns to 30 microns. In the example of fig. 3A, the length of the first DBR section 306 may be 15 microns. Alternatively, the first DBR section 306 may have a length in a range from 30 microns to 100 microns. The first kappa of the first DBR grating 310 may be relatively strong, e.g., at least 250 per centimeter (cm)^-1) Or greater or less than 250cm^-1. In the example of fig. 3A, the first kappa of the first DBR grating 310 may be 500cm^-1. In some embodiments, the first DBR grating 310 may have a kappa times length or κ L value in the range from 0.5 to 1.0. For example, the first DBR grating 310 may have a length L of 15 microns, 500cm^-1Kappa and kappa L of 0.75.

The second DBR section 308 can include a second DBR grating 312 having a second kappa. The second DBR section 306 may be relatively long, such as 120 microns or longer, or in the range from 120 microns to 250 microns. In the example of fig. 3A, the length of the second DBR section 308 can be 150 microns. The second kappa of the second DBR grating 312 may be smaller than the first kappa of the first DBR grating 310. For example, the second kappa of the second DBR grating 312 may be 80cm^-1Or smaller. In some embodiments, the second DBR grating 312 may have a value of κ L ranging from 0.5 to 1.0. For example, the second DBR grating 312 may have a length L of 200 microns, 43cm^-1Kappa and kappa L of 0.86.

As shown in FIG. 3A, the second DBR grating 312 comprises a grating having a width of 80cm^-1Effective kappa sampling grating. In general, the kappa of a DBR grating as used herein may refer to the effective kappa of the DBR grating, in the case of a uniform gratingThe effective kappa of the DBR grating may be the same as the actual kappa.

Active region 304 may include a Multiple Quantum Well (MQW) gain layer 314 or other suitable gain layer and may be configured to operate in a lasing mode. In the example of fig. 3A, active region 304 may have a length of 50 microns.

A highly reflective mirror 316 (also referred to as a back mirror) is formed at a back 317 of the active region 304, e.g., on the back facet. The high mirror 316 may be coupled to a rear portion 317 of the active region 304. The high mirror 316 may have a reflectivity of 30% or more. The highly reflective mirror 316, the active region 304, and the first DBR section 306 may form a fabry-perot (FP) cavity 318 that may increase the longitudinal confinement factor of the dual-kappa DBR laser 300 compared to a uniform (e.g., single-kappa) DBR laser. The addition of the second DBR section 308 at the output of the fabry-perot cavity 318 produces a detuned loading effect in the dual-kappa DBR laser 300. Thus, modulation of the active region 304 can modulate the cavity loss and increase the intrinsic speed of the dual-kappa DBR laser 300.

As shown in fig. 3A, the dual-kappa DBR laser 300 may additionally include a modulation contact 322 electrically coupled to the active region 304, a first bias contact 324 electrically coupled to the first DBR section 306, and a second bias contact 326 electrically coupled to the second DBR section 308, respectively.

A modulation signal 328 may be provided to active region 304 through modulation contact 322 to modulate active region 304. Modulation of the active region 304 may modulate the cavity loss of the dual-kappa DBR laser 300 and may increase the carrier-photon resonant frequency (F) of the dual-kappa DBR laser 300_r)。

The first bias signal 330 may be provided to the first DBR section through a first bias contact 324. A second bias signal 332 may be provided to the second DBR section via a second bias contact 326. Alternatively or additionally, current tuning may be applied to one or both of the first DBR section 306 and the second DBR section 308 as described elsewhere herein to tune the PPR frequency of the dual kappa DBR laser 300.

In some embodiments, the dual-kappa DBR laser 300 may further include a Low Reflection (LR) mirror formed at the output end facet of the second DBR section 308 to improve the side mode suppression ratio. The LR mirror can have a reflectivity of, for example, 1% or less.

Fig. 3B illustrates a reflection curve 334 of the first DBR section 306 (hereinafter the first DBR reflection curve 334), a reflection curve 336 of the second DBR section 308 (hereinafter the second DBR reflection curve 336), and a reflection curve 338 of the dual kappa DBR laser 300 as a whole (hereinafter the dual kappa DBR laser reflection curve 338) arranged in accordance with at least one embodiment described herein. As shown by the first DBR reflection curve 334, the first DBR section 306 has a wide DFB reflection peak with a relatively low maximum reflection. As shown by the second DBR reflection curve 336, the second DBR section 308 has a very narrow DFB reflection peak with a relatively steep long wavelength edge. The double kappa DBR laser reflection curve 338 is the overall reflection curve of the double kappa DBR laser 300 according to the combination of the first DBR reflection curve 334 and the second DBR reflection curve 336. As shown, the long wavelength edge of the double kappa DBR laser reflection curve 338 is steeper at the lasing mode 340 of the active region 304 than the long wavelength edge of the second DBR reflection curve 336. The long wavelength edge of the DFB reflection peak of the double-kappa DBR laser reflection curve 338 may have at least 0.002GHz^-1E.g., about 0.006GHz at the lasing mode 340 of the dual-kappa DBR laser 300^-1The slope of (a). In some embodiments, the slope may be from 0.002GHz^-1To 0.009GHz^-1Within the range of (1).

Fig. 3B also shows the PPR mode 342 of the dual-kappa DBR laser 300. The PPR mode 342 may have a PPR frequency in the range of 20GHz to 80 GHz. Alternatively or additionally, the PPR frequency may be tuned over a range by detuning the first DBR section 306 and the second DBR section 308 with respect to each other using current tuning. The tuning range of the PPR frequency may be 20GHz to 80 GHz.

Fig. 3C illustrates a distribution 344 of reactive photons during lasing in three different example lasers arranged in accordance with at least one embodiment described herein. These three example lasers include a Distributed Reflector (DR) laser as disclosed in patent 10,063,032, a DBR laser with uniform kappa, and the dual kappa DBR laser 300 of fig. 3A. In fig. 3C, the distribution 344 is normalized over the active area. For example, the labels of the "MQW" and "DBR" and the arrows across the top of the graph of the distribution 344 indicate the position of the MQW or active region and the DBR region (formed by the first DBR section 306 and the second DBR section 308 in the case of the dual-kappa DBR laser 300) in all three exemplary lasers. The distribution 344 includes a distribution 344A of a DR laser, a distribution 344B of a dual-kappa DBR laser 300, and a distribution 344C of a DBR laser having uniform kappa. For the distribution 344B of the dual-kappa DBR laser 300, the region 344D of the DBR section corresponds to the first DBR section 306 of the dual-kappa DBR laser 300, while the remainder of the DBR section in the distribution 344B corresponds to the second DBR section 308.

The first DBR section 306 generally confines the reactive photons to the active region 304 as shown in distribution 344B. As shown, the distribution 344B of the reactive photons drops significantly from the active region 304 to the second DBR section 308 through the first DBR section 306. In an example, the distribution 344 of the reactive photons decreases by at least 50% from the active region 304 to the second DBR section 308 through the first DBR section 306. As shown in distribution 344C, significantly more light penetrates into the passive/DBR section of the DBR laser with uniform kappa, which weakens the differential gain and slows down the DBR laser with uniform kappa.

Fig. 3D illustrates a modulation spectrum 346 and various S21 responses 348 of the dual-kappa DBR laser 300 of fig. 3A arranged in accordance with at least one embodiment described herein. Modulation spectrum 346 includes lasing mode 340 and PPR mode 342. The frequency difference between the lasing mode 340 and the PPR mode 342 may be referred to as the PPR frequency. The PPR frequency appears as a peak in the S21 response 348 at approximately 60 GHz.

An embodiment of the dual-kappa DBR laser 300 having a 50 micron active region 304 may have a 3dB bandwidth of about 30GHz or greater (e.g., 35GHz) or even 60GHz or greater (e.g., 65GHz) at room temperature for 50Gbaud of PAM 4. An embodiment of the dual-kappa DBR laser 300 having a 100 micron active region 304 may have a 3dB bandwidth at 70C of 50GHz or greater.

Fig. 4 illustrates an example split-contact DR laser 400 arranged in accordance with at least one embodiment described herein. As shown, split-contact DR laser 400 includes an inactive region 402 and an active region 404. The passive region 402 may have a length of approximately 215 microns or other suitable length. Active region 404 may have a length of approximately 50 microns or other suitable length.

The passive region 402 includes, for example, a DBR grating 406 having uniform kappa. The active region includes a DFB grating 408 formed in or over the active region, for example in or over the MQW layer 410.

A highly reflective mirror 412 (also referred to as a back mirror) is formed on the back facet of the active region 404. The high mirror 412 may have a reflectivity of 30% or more.

An anti-reflective (AR) coating 414 may be formed on the front facet of the passive region 402.

As shown in fig. 4, the split-contact DR laser 400 may additionally include a modulation contact 416 and first and second bias contacts 418 and 420. The modulation contacts 416 are electrically coupled to the active region 404. The first bias contact 418 is electrically coupled to a first portion of the inactive region 402 that may have a length of about 140 microns. The second bias contact 420 is electrically coupled to a second portion of the inactive region 402 that may have a length of about 75 microns. A modulation signal 422 may be provided to active region 404 through modulation contact 416. The first bias signal 424 may be provided to the first portion of the inactive region 402 through the first bias contact 418. A second bias signal 426 may be provided to a second portion of the inactive region through a second bias contact 420.

Current tuning may be applied to one or both of the first and second biasing contacts 418, 420 to tune the PPR frequency of the split-contact DR laser 400. For example, by applying different bias signals 424, 426 to the first and second bias contacts 418, 420, the first and second portions of the inactive region 402 may be tuned relative to each other to tune the PPR frequency of the split-contact DR laser 400.

Fig. 5 illustrates another example dual-kappa DBR laser 500 arranged in accordance with at least one embodiment described herein. As shown, the dual-kappa DBR laser 500 includes an inactive region 502, an active region 504, and an optional Semiconductor Optical Amplifier (SOA) region 506. The passive region 502 may have a length of approximately 215 microns or other suitable length. Active region 504 may have a length of approximately 50 microns or other suitable length. The inactive region 502 and the active region 504 may be the same as or similar to the inactive region 302 and the active region 304 of the dual-kappa DBR laser 300 of fig. 3, except as otherwise noted herein.

The passive region 502 may include a first DBR section 508 and a second DBR section 510. The first DBR section 508 can include a first DBR grating 512 having a first kappa. The length of the first DBR section 508 can be 15 microns or other suitable length. The second DBR section 510 can have a second DBR grating 514, the second DBR grating 514 having a second kappa different from and less than the first kappa. The length of the second DBR section 510 can be 200 microns or other suitable length.

Active region 504 includes an active region such as MQW layer 516.

A high reflecting mirror 518 (also referred to as a back mirror) is formed at the back 519 of the active region 504, for example, on the back facet. High mirror 518 may be coupled to a rear portion 519 of active region 504. The high mirror 518 may have a reflectivity of 30% or more.

An anti-reflection (AR) coating 520 may be formed at the front 521 of the SOA region 506, for example, on the front facet. The AR coating 520 may be coupled to the front 521 of the SOA region 506.

As shown in fig. 5, the dual-kappa DBR laser 500 may additionally include a modulation contact 522, a first bias contact 524, a second bias contact 526, a third bias contact 528, and a fourth bias contact 530. The modulation contact 522 is electrically coupled to the active region 504. The first bias contact 524 is electrically coupled to the first DBR section 508. The second bias contact 526 is electrically coupled to a first portion of the second DBR section 510 that may have a length of about 140 microns or other suitable length. The third bias contact 528 is electrically coupled to a second portion of the second DBR section 510 that may have a length of about 60 microns or other suitable length. The fourth bias contact 530 is electrically coupled to the SOA region 506.

In fig. 5, the second DBR section 510 has separate contacts, for example, a second bias contact 526 and a third bias contact 528, as opposed to the single bias contact (e.g., the second bias contact 326) of the second DBR section 308 of fig. 3. Thus, the dual-kappa DBR laser 500 may be referred to as a split-contact dual-kappa DBR laser 500.

A modulation signal 532 may be provided to active region 504 through modulation contact 522. Modulation of the active region 504 may modulate the cavity loss of the dual-kappa DBR laser 500 and may increase the F of the dual-kappa DBR laser 500_r。

The first bias signal 534 may be provided to the first DBR section 508 through a first bias contact 524. A second bias signal 536 may be provided to the first portion of the second DBR section 510 through a second bias contact 526. A third bias signal 538 may be provided to the second portion of the second DBR section 510 through a third bias contact 528. The fourth bias signal 540 and/or the modulation signal may be provided to the SOA region 506 through the fourth bias contact 530.

Current tuning may be applied to one or both of the second bias contact 526 and the third bias contact 528 to tune the PPR frequency of the dual-kappa DBR laser 500. For example, the first and second portions of the second DBR section 510 of the passive region 502 may be tuned relative to each other by applying different second and third bias signals 536, 538 to the second and

third bias contacts

526, 528 to tune the PPR frequency of the dual-kappa DBR laser 500.

Fig. 6 illustrates a modulation response 602 and PPR tunability 604 of the split-contact DR laser 400 of fig. 4 arranged in accordance with at least one embodiment described herein. A split-contact dual-kappa DBR laser such as the dual-kappa DBR laser 500 of fig. 5 may similarly have PPR tunability. The split-contact DR laser 400 may have an F of about 25GHz as shown by the modulation response 602_r。

As shown by the PPR tunability 604, the PPR frequency of the split-contact DR laser 400 can be tuned between 20GHz and 80GHz by applying an appropriate combination of gain biasing and current tuning to one or more of the first portion of the passive region 402 (referred to as "DBR 1" in fig. 6) and the second portion of the passive region 402 (referred to as "DBR 2" in fig. 6).

For example, for a gain bias of about 38 milliamps (mA) to about 46mA with the first portion of the passive region 402 (DBR1) tuned to about 4mA, the PPR frequency is in the range of about 81GHz to about 71GHz as shown by the topmost curve of the PPR tunability 604 (e.g., the curve labeled with the oval point). As another example, for a bias gain of about 40mA to about 50mA with the first portion (DBR1) tuned to about 2mA, the PPR frequency is in the range of about 71GHz to about 55GHz as shown by the next curve (e.g., the curve labeled with the x-point) below the topmost curve of the PPR tunability 604.

The invention can also be realized by the following technical scheme:

1. a dual-kappa distributed bragg reflector laser comprising:

a fabry-perot cavity comprising a highly reflective mirror, a first distributed bragg reflector region, and an active region, the active region being located between the highly reflective mirror and the first distributed bragg reflector region, the first distributed bragg reflector region comprising a first distributed bragg reflector grating having a length L1 in the range of 10 to 30 microns and a first kappa 1, wherein kappa 1L1 is in the range of 0.5 to 1.0; and

a second distributed Bragg reflector region coupled to the Fabry-Perot cavity, the second distributed Bragg reflector region comprising a second distributed Bragg reflector grating having a second kappa 2 that is less than the first kappa 1 of the first distributed Bragg reflector region.

2. The dual kappa distributed bragg reflector laser of claim 1, wherein the length L2 of the second distributed bragg reflector region is in a range of 120 microns to 250 microns, and wherein κ 2L2 is in a range of 0.5 to 1.0.

3. The double-kappa distributed bragg reflector laser according to claim 1, wherein:

the dual-kappa distributed Bragg reflector laser is configured to operate in a lasing mode;

the double-kappa distributed Bragg reflector laser has a distributed Bragg reflector reflection curve comprising a distributed Bragg reflector reflection peak; and

the lasing mode is aligned to a long wavelength edge of a reflection peak of the distributed bragg reflector.

4. The dual kappa distributed bragg reflector laser of claim 3, wherein a long wavelength edge of the distributed bragg reflector reflection peak has greater than 0.002 gigahertz at the lasing mode^-1The slope of (a).

5. The double-kappa distributed bragg reflector laser according to claim 1, further comprising a photon-photon resonance frequency in a range of 20 to 80 gigahertz.

6. The dual-kappa distributed bragg reflector laser of claim 1, further comprising a first bias contact electrically coupled to a first portion of the second distributed bragg reflector region and a second bias contact electrically coupled to a second portion of the second distributed bragg reflector region, wherein a photon-photon resonant frequency of the dual-kappa distributed bragg reflector laser is tunable in response to application of a tuning current to the first bias contact or the second bias contact.

7. The dual kappa distributed bragg reflector laser of claim 1, wherein the 3db bandwidth of the dual kappa distributed bragg reflector laser at room temperature is at least 60 ghz.

8. The dual kappa distributed bragg reflector laser of claim 1, wherein during lasing the first distributed bragg reflector region is configured to confine reactive photons to the active region.

9. The dual-kappa distributed bragg reflector laser of claim 8, wherein during lasing the distribution of the reactive photons decreases by at least 50% from the active region to the second distributed bragg reflector region through the first distributed bragg reflector region.

10. A dual-kappa distributed bragg reflector laser comprising:

an active region;

a high mirror coupled to a rear of the active region;

a first distributed Bragg reflector region coupled to a front of the active region, the first distributed Bragg reflector region having a first distributed Bragg reflector grating having a first kappa 1; and

a second distributed Bragg reflector region coupled to a front of the first distributed Bragg reflector region such that the first distributed Bragg reflector region is located between the active region and the second distributed Bragg reflector region, the second distributed Bragg reflector region having a second distributed Bragg reflector grating having a second kappa 2 smaller than the first kappa 1,

wherein the dual-kappa DBR laser is configured to operate in a lasing mode and has a DBR reflection curve including a DBR reflection peak, and wherein the lasing mode is aligned to a long wavelength edge of the DBR reflection peak.

11. The dual kappa distributed bragg reflector laser of claim 10, wherein the length L1 of the first distributed bragg reflector region is in the range of 10 microns to 30 microns and κ 1L1 is in the range of 0.5 to 1.0.

12. The dual kappa distributed bragg reflector laser of claim 10, wherein the length L2 of the second distributed bragg reflector region is in a range of 120 to 250 microns and κ 2L2 is in a range of 0.5 to 1.0.

13. The double kappa distribution according to claim 10A distributed bragg reflector laser, wherein a long wavelength edge of a reflection peak of the distributed bragg reflector has at least 0.002 gigahertz in the lasing mode^-10The slope of (a).

14. The double-kappa distributed bragg reflector laser according to claim 10, further comprising a photon-photon resonance frequency in a range of 20 to 80 gigahertz.

15. The dual-kappa distributed bragg reflector laser of claim 10, further comprising a first bias contact electrically coupled to a first portion of the second distributed bragg reflector region and a second bias contact electrically coupled to a second portion of the second distributed bragg reflector region, wherein a photon-photon resonant frequency of the dual-kappa distributed bragg reflector laser is tunable by applying a tuning current to the first bias contact or the second bias contact.

16. The dual kappa distributed bragg reflector laser of claim 10, wherein during lasing the first distributed bragg reflector region is configured to confine reactive photons to the active region.

17. The dual-kappa distributed bragg reflector laser of claim 16, wherein, during lasing, the distribution of the reactive photons has a peak within the active region that is at least twice the value of the distribution at any location within the second distributed bragg reflector region.

18. The dual-kappa distributed bragg reflector laser of claim 10, further comprising a modulation contact coupled to the active region and configured to provide a modulation signal to the active region to modulate the active region, wherein the modulation of the active region modulates a cavity loss of the dual-kappa distributed bragg reflector laser and increases a carrier-photon resonance frequency of the dual-kappa distributed bragg reflector laser.

19. The double-kappa distributed bragg reflector laser according to claim 10, further comprising a low mirror formed at an output end surface of the second distributed bragg reflector region.

20. The double-kappa distributed bragg reflector laser according to claim 10, further comprising a semiconductor optical amplifier region coupled to a front portion of the second distributed bragg reflector region.

Claims

1. A dual-kappa distributed bragg reflector laser comprising:

2. The dual kappa distributed bragg reflector laser of claim 1, wherein a length L2 of the second distributed bragg reflector region is in a range of 120 microns to 250 microns, and wherein κ 2L2 is in a range of 0.5 to 1.0.

3. The dual kappa distributed bragg reflector laser of claim 1, wherein:

5. The dual-kappa distributed bragg reflector laser of claim 1, further comprising a photon-photon resonant frequency in a range of 20 gigahertz to 80 gigahertz.

7. The dual kappa distributed bragg reflector laser of claim 1, wherein the dual kappa distributed bragg reflector laser has a 3 decibel bandwidth of at least 60 gigahertz at room temperature.

8. The dual kappa distributed bragg reflector laser of claim 1, wherein during lasing, the first distributed bragg reflector region is configured to confine reactive photons to the active region.

9. The dual kappa distributed bragg reflector laser of claim 8, wherein a distribution of the reactive photons decreases by at least 50% through the first distributed bragg reflector region from the active region to the second distributed bragg reflector region during lasing.

10. A dual-kappa distributed bragg reflector laser comprising:

an active region;

a high mirror coupled to a rear of the active region;