BACKGROUND

Cross-Refer en ce

[0001] This application claims the benefit of priority under 35 U.S. C. § 119 of U.S.

Provisional Application Serial No. 61/369,512 filed on July 30, 2010 the content of which is relied upon and incorporated herein by reference in its entirety.

Field

[0002] The present specification generally relates to wavelength converted light sources and, more specifically, to package designs for semiconductor laser diodes utilized in wavelength converted light sources.

Technical Background

[0003] Wavelength converted light sources incorporating semiconductor laser and a wavelength conversion device may be incorporated into various electronic devices such as microprojectors. As these light sources are incorporated into more and more electronics, the demand for greater resolutions and improved display characteristics has also increased.

Current solutions to improve resolution and display characteristics of the devices have resulted in device designs with increased power consumption, impedance and/or inductance, all of which ultimately impact the power consumed by the device. While such solutions may be effective in limited circumstances, such solutions may not be effectively implemented in wavelength converted light sources with a fixed power supply, such as a battery.

[0004] Accordingly, a need exists for alternative package designs for wavelength converted light sources which will improve the power consumption of the devices.

SUMMARY

[0005] According to one embodiment, a system for packet designs for wavelength converted light sources includes a signal trace that is formed by a rigid printed circuit board (PCB) and a hybrid PCB coupled to the first signal trace by a wire bond, wherein the inductance along the wire bond is minimized.

[0006] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0007] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 depicts an wavelength converted light source, in which a semiconductor laser , a wavelength conversion device, and adaptive optics are oriented in a folded configuration, according to various embodiments described herein;

[0009] FIGS. 2 A - 2C depict various perspectives of portions of a package design for converting a semiconductor laser to a laser drive circuit , illustrating a rigid printed circuit board with flex extension, according to embodiments described herein;

[0010] FIGS. 3A - 3C depict another embodiment of a package design for a semiconductor laser from FIG. 1, further illustrating a double layer flexible PCB mounted on top of a metal base, according to embodiments disclosed herein;

[0011] FIG. 4 depicts a 3-dimensional view of the rigid PCB, according to embodiments disclosed herein;

[0012] FIG. 5 depicts a 3-dimensional view for a flex model, according to embodiments disclosed herein;

[0013] FIG. 6 depicts a summary of inductance patterns for the wavelength converted light source, according to various embodiments disclosed herein; [0014] FIG. 7 depicts a graphical representation of a summary of inductance parameters, according to various embodiments disclosed herein; and

[0015] FIG. 8 depicts a circuit diagram, such as may be simulated for the embodiment of the package design depicted in FIGS. 2A - 2C.

DETAILED DESCRIPTION

[0016] Embodiments disclosed herein relate to packaging for a wavelength converted light source, which may be used in red green blue (RGB) laser based projectors. The packaging described herein may assist in high resolution image projection and frequency converted light source with high electrical power efficiency. Embodiments of the wavelength converted light source described herein are based on a high efficiency 1060 nm distributed Bragg reflector (DBR) laser and a highly efficient waveguide-based second harmonic generation (SHG) crystal. Optically coupled with a single scanning micro -electro -mechanical system (MEMS) mirror. In the embodiments described herein, the frequency converted light source projects each point by point much like a cathode ray tube (CRT). For high resolution image generation (e.g., 720p), pixel projection rates of greater than 150 Mpixels/s are utilized. For example, the 1060 DBR laser is capable of greater than 500 MHz modulation bandwidth (BW), which is sufficient to high resolution image projection. This feature, coupled with single pass optical architecture, ensures that there is an intrinsic capability to easily meet high resolution projection needs. Additionally, the high intensity output of the frequency converted light source utilizes a large current, greater than 600 milli- Amperes (mA).

[0017] The challenge of supporting the desired high frequency modulation lies in enabling large current swings and high speeds through the electrical interconnects, such as wire bonds, which interconnect the laser drive circuit and the semiconductor laser. Critical parameters that are to be optimized include the inductance and the impedance of the electrical interconnects. Specifically, in embodiments disclosed herein, the inductance of the semiconductor laser packaging is minimized and the impedance is configured to be close to that of the 1060 diode. For a given laser, the inductance specification is proportional to current swing. The current drive requirement of the semiconductor laser 1 10 of the wavelength converted light source 100 (FIG. 1) is 6 times that of the complimentary red and blue lasers utilized in a projector system and thus realizes a significant improvement in inductance. Regarding impedance, the semiconductor laser 1 10 laser has a low impedance (e.g., 1-2 ohms), and as such, matching this impedance in the semiconductor laser interconnect packaging is also a critical factor to ensuring the ability to drive wavelength converted light sources at high speed.

[0018] In current solutions, high speed modulation packages generally fall into two categories that do not overlap with the requirements of this product space. 1) High speed digital interfaces, which tend to be low currents at high impedances of 50-100 ohms in the 100s of MHz; and 2) High speed analog signals used in laser communications. In the case of the high speed analog laser drive systems, these tend to have very relaxed power consumption and drive band-limited at frequencies in the multiple GHz range. Because of the less critical power consumption target and band-limited performance network, matching components and circuits can be used. In the case of the wavelength converted light source for an embedded application, embodiments disclosed herein support broad band frequencies from DC up to greater than 500 Mhz, while having minimal overhead power consumption in the drive and support electronics.

[0019] For example, in at least one embodiment, a wavelength converted light source (see wavelength converted light source 100 of FIG. 1), modulation requirements which may include support for SVGA, 720p, running at 150 Mhz, and having a 2.5 ns rise and fall time. Additional specifications include rise and fall time requirements drive inductance specification, including an overhead voltage = V = L*di/dt, 1 nano-Henries (nH) = 260 mV Voltage Overhead @ 2.5 ns tr/tf, 2 nH = 520 mV Voltage Overhead @ 2.5 ns tr/tf, and 3 nH = 780 mV Voltage Overhead @ 2.5 ns tr/tf. Additionally, voltage overhead can become a penalty to enable high speed rise and fall times when the wavelength converted light source is running at 80 mW, when Igain = 650mA, Vgain = 1.8V, 1 nH -> 14% increase in Gain Section power consumption under static conditions, 2 nH -> 28% increase in Gain Section power

consumption under static conditions, 3 nH -> 42% increase in gain section power

consumption under static conditions, and the wavelength converted light source 100 is running at 650 mA, with a laser utilizing approximately 1.1 W. Further, including power consumption overhead = 169 mW (1 nH) or 338 mW (2 nH) or 507 mW (3 nH) and, assuming the laser is nominally at 8%- excluding overhead voltage to support modulation rate requirements, it can degrade effective WPE to 6.8 % (1 nH) or 5.6% (2 nH) or 4.4% (3 nH). Additional specifications may include a design target total inductance target of 2 nH, and an allocation of an absolute maximum of 1.5 nH for all wire-bonds included in the semiconductor laser interconnect packaging. Further an allocation of 0.5 nH for combination of flex and rigid PCB design elements can also be made.

[0020] Embodiments disclosed herein include an optimized semiconductor laser package interconnect to achieve low cost and , enable efficient electrical power systems, while meeting the high speed modulation requirements over a current swing of greater than or equal to 600 mA. The resulting design includes a characteristic low impedance (an overall impedance of less than or equal to approximately 3 ohm) and low inductance (an overall inductance of less than or equal to approximately 3 nH).

[0021] Additionally, embodiments disclosed herein may be configured to minimize the total effective inductance for all electrical lead components in the high current path, avoid the use of high impedance matching networks to maximize electrical power efficiency, and utilize a low cost multi-layer rigid PCB within the package with optimized trace geometries and layer definitions. Similarly, some embodiments may be configured to utilize a low cost double sided flexible circuit PCB within the package optimized trace geometries and layer definitions, utilize optimized wire bond layout configurations, and utilize a low impedance interconnect design with a package to match the impedance of the semiconductor laser.

[0022] Embodiments of the semiconductor laser interconnect packaging disclosed herein enable a high modulation speed for high current, low impedance applications greater than or equal to approximately 200 Mhz compared to standard package interconnects (such lead frames that support 125 Mhz systems) enable low system power consumption, optimize impedance of the electrical interconnect to match that of the semiconductor laser, maintain consistent low impedance throughout the package interconnects, support overall low cost sub components, and support compact package design.

[0023] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. It should be understood that in FIG. 1, the solid lines and arrows indicate the electrical mterconnectivity of various components of the wavelength converted light sources. These solid lines and arrows are also indicative of electrical signals propagated between the various components including, without limitation, electronic control signals, data signals and the like. Further, it should also be understood that the dashed arrows indicate light beams, such as infrared and/or visible light beams, emitted by the semiconductor laser and the wavelength conversion device.

[0024] Accordingly, embodiments disclosed herein include a semiconductor laser interconnect packaging for interfacing a semiconductor laser of a wavelength converted light source to a laser drive circuit. As such, embodiments disclosed here may be configured to reduce impedance, inductance, and/or power consumption with the structure and parameters, described herein.

[0025] Referring initially to FIG. 1, wavelength converted light source 100 in which the semiconductor laser packaging may be employed includes, for example, a semiconductor laser 110 optically coupled to a wavelength conversion device 120, as well as to a laser drive circuit (not explicitly shown in FIG. 1), that is configured to provide power to the semiconductor laser 110. A fundamental beam 119 is coupled into the waveguide portion of wavelength conversion device 120 using adaptive optics 140. The wavelength conversion device 120 converts the fundamental beam 119 (such as an infrared light beam) into higher harmonic waves and outputs a wavelength converted output beam 128. This type of wavelength converted light source is particularly useful in generating shorter wavelength laser beams from longer wavelength semiconductor lasers and can be used, for example, as a visible laser source for laser projection systems.

[0026] Additionally, the output of the semiconductor laser 110 and the input of the wavelength conversion device 120 are positioned on different optical axes. The fundamental beam 119 emitted by the semiconductor laser 110 is directed into the waveguide portion of the wavelength conversion device 120 with adaptive optics 140. Further, the fundamental beam 119 is redirected from its initial pathway in order to facilitate coupling of the fundamental beam 119 into the waveguide portion of the wavelength conversion device 120. Accordingly, in this embodiment, the adaptive optics 140 may include an adjustable optical component, specifically an adjustable mirror 144, and a lens 142. The lens 142 of the adaptive optics 140 may collimate and focus the fundamental beam 119 emitted by the semiconductor laser 110 into the waveguide portion of the wavelength conversion device 120.

[0027] The adjustable mirror 144 may be rotated about a first scanning axis substantially parallel to the x-axis depicted in FIG. 1 and about a second scanning axis substantially parallel to the y-axis to introduce angular deviation in the fundamental beam 119. The adjustable mirror 144 may include a mirror portion and an actuator portion and the adjustable mirror 144 may be rotated about either scanning axis by adjusting the actuator portion of the adjustable optical component.

[0028] In one embodiment, the adjustable mirror 144 may include one or more movable micro-opto-electromechanical systems (MOEMS) or micro-electro-mechanical system

(MEMS) operatively coupled to a mirror. The MEMS or MOEMS devices may be configured and arranged to vary the position of the fundamental beam 119 on the input facet of the wavelength conversion device 120. Use of MEMS or MOEMS devices enables adjustment of the fundamental beam 119 to be performed rapidly over large ranges. For example, a MEMS mirror with a +/- 1 degree mechanical deflection, when used in conjunction with a 3 mm focal length lens, may allow the beam spot to be angularly displaced +/- 100 μιη on the input face of the wavelength conversion device 120. The adjustment of the beam spot may be done at frequencies on the order of 100 Hz to 10 kHz due to the fast response time of the MEMS or MOEMS device.

[0029] In the wavelength converted light source 100, the adjustable mirror 144 is a micro- opto-electromechanical mirror incorporated in a relatively compact, folded-path optical system. The adjustable mirror 144 is configured to fold the optical path such that the optical path initially passes through the lens 142 to reach the adjustable mirror 144 as a collimated or nearly collimated beam and subsequently returns through the same lens 142 to be focused on the wavelength conversion device 120. This type of optical configuration is particularly applicable to wavelength converted laser sources where the cross-sectional size of the laser beam generated by the semiconductor laser 110 is close to the size of the waveguide on the input face of the wavelength conversion device 120, in which case a magnification close to one would yield optimum coupling in focusing the beam spot on the input face of the wavelength conversion device 120. For the purposes of defining and describing this embodiment of the wavelength converted light source 200, it is noted that reference herein to a "collimated or nearly collimated" beam is intended to cover any beam configuration where the degree of beam divergence or convergence is reduced, directing the beam towards a more collimated state.

[0030] Still referring to FIG. 1, the wavelength converted light source 100 may also include a filtering window 179 positioned proximate the output of the wavelength conversion device 120. The filtering window prevents non-wavelength converted light (i.e., infrared light in the embodiments shown and described herein) from being emitted from the wavelength converted light source 100. Accordingly, it will be understood that, once the wavelength converted output beam 128 exits the wavelength converted light source 100, the wavelength converted output beam 128 only contains wavelength converted light.

[0031] The wavelength converted light source 100 may also include a package controller 150. The package controller 150 may include one or more micro-controllers or programmable logic controllers used to store and execute programmed instructions for operating the wavelength converted light source 100. Similarly, in some embodiments, the micro-controllers or programmable logic controllers may directly execute an instruction set. The package controller 150 may be electrically coupled to the semiconductor laser 110, the adaptive optics 140 and an optical detector 170 and programmed to operate both the semiconductor laser 110 and the adaptive optics 140. More specifically, in one embodiment, the package controller 150 may include drivers 152, 154 for controlling the adaptive optics and the wavelength selective section of the semiconductor laser, respectively.

[0032] The adaptive optics driver 152 may be coupled to the adaptive optics 140 with leads 152, 158 and supplies the adaptive optics 140 with x- and y- position control signals through the leads 152, 158, respectively. The x- and y- position control signals facilitate positioning the adjustable optical component of the adaptive optics in the x- and y- directions which, in turn, facilitates positioning the fundamental beam 119 of the semiconductor laser 110 on the input facet of the wavelength conversion device 120. For example, when the adjustable optical component of the adaptive optics 140 is an adjustable mirror 144, as shown in FIG. 1, the x- and y- position control signals may be used to rotate the adjustable mirror 144 about the first scanning axis and the second scanning axis such that the fundamental beam 119 of the semiconductor laser 110 is scanned over the input facet of the wavelength conversion device 120.

[0033] The wavelength selective section driver 154 may be coupled to the semiconductor laser 110 with lead 155. The wavelength selective section driver 154 may supply the wavelength selective section 112 of the semiconductor laser 110 with wavelength control signal(s) which facilitate adjusting the wavelength λι of the fundamental beam 119 emitted from the output facet of the semiconductor laser 110. [0034] Further, the output of the optical detector 170 may be electrically coupled to an input of the package controller 150 with lead 172 such that the output signal of the optical detector 170 is passed to the package controller 150.

[0035] The wavelength converted light source 100 shown in FIG. 1 may be coupled to a data source 160, such a programmable logic controller, which supplies the wavelength converted light source 100 with an encoded data signal which may be representative of a video image, still image or the like. More specifically, the data source 160 may be coupled to the gain section of the semiconductor laser 110 via lead 162. The data source 160 may control the periodic lasing intensity of the semiconductor laser 110 such that the output of the wavelength converted light source 100, 200 forms an image when projected. To control the periodic lasing intensity of the semiconductor laser 110, the encoded data signal injects a gain current IGAIN into the gain section of the semiconductor laser 110. Typically, the periodic frequency VDATA of the gain current I _G AIN is representative of the video image or still image of the encoded data signal such that, when the output of the wavelength converted light source is projected, as modulated by the periodic frequency V _D ATA of the gain current IGAIN, the projected image is the video image or still image of the encoded data signal. Generally, the periodic frequency V _D ATA of the encoded data signal is about 60 Hz which generally corresponds to the video frame rate of a projected image.

[0036] FIGS. 2A - 2C depict various perspectives of the semiconductor laser 110, positioned on a semiconductor laser interconnect package 200, further illustrating a rigid printed circuit board with flex extension, according to embodiments described herein. More specifically, as illustrated in FIG. 2A, the semiconductor laser interconnect package 200 includes a plurality of stacked ground layers 202 that are formed of rigid printed circuit board (PCB) and reside on a base 203. Depending on the particular embodiment, the base 203 may be constructed of a conductive material and/or a nonconductive material. Additionally, coupled to one end of the stacked ground layers 202 is a first signal trace 204 that is formed of a rigid PCB top. Coupled the first signal trace 204 and overhanging the edge of the first signal trace 204 is a second signal trace 206 formed of a flex PCB bottom. Coupled to the second signal trace is a ground layer top 208, formed of a first flex PCB. Between the second signal trace 206 and the ground layer top 208 is a non-conductive layer 209. [0037] Also included in FIG. 2A is a hybrid PCB 210, which is electrically coupled to the first signal trace 204 via a first departure wire bond 212a, where the first departure wire bond 212a includes one or more connections. Similarly, the hybrid PCB 210 is electrically coupled to a semiconductor laser 110 via a second departure wire bond 213, which may also include one or more connections.

[0038] Similarly, FIG. 2B illustrates the semiconductor laser 110 of FIG 2A, from a top perspective. Accordingly, the connection of the ground layer top 208 and the first signal trace 204 is clearly illustrated. Similarly, the first departure wire bond 212a are clearly shown as electrically coupling the first signal trace 204 and the hybrid PCB 210. The second departure wire bond 213 are illustrated forming a connection between the hybrid PCB 210 and the semiconductor laser 110. As shown, the first departure wire bond 212a are utilized for a signal being sent to the hybrid PCB 210 from the first signal trace 204 and the return wire bond 212b is utilized for a signal being sent from the hybrid PCB 210 back to the first signal trace 204. These signal paths are directed across different trace paths 211a, 211b on the non- conductive layer 209, below the ground layer top 208, as illustrated by dashed lines.

[0039] FIG. 2C illustrates the semiconductor laser interconnect package 200 of FIGS. 2A and 2B from another side perspective. As illustrated, FIG. 2C depicts vias 216 connecting the ground layer top 208 and a ground trace bottom 218, which is formed with a second flex PCB. Of particular interest in FIG. 2C is the utilization of a portion of the first departure wire bond 212a, without inclusion of the second departure wire bond 213. FIG. 2C is depicted in such a manner to illustrate the path of the return signal. More specifically, the return signal is sent to the hybrid PCB 215 via a direct connection between the semiconductor laser 110 and a conductive layer 217. The conductive layer 217 transmits the return signal to the hybrid PCB 215 without the use of wire bonds 212, 213.

[0040] For example, with regard to FIGS. 2A - 2C a method for modulating a signal may include a laser drive circuit being configured to send a signal across the second signal trace 206 of the semiconductor laser 110 (FIG. 2A). The signal may traverse the first trace path 21 la to the first signal trace 204a (FIG. 2B). From the first signal trace 204, the signal is sent via the first departure wire bond 212a to the hybrid PCB 210 (FIG. 2B). From the hybrid PCB 210, the signal is sent via the second departure wire bond 213 to the semiconductor laser 110 (FIG. 2B). The semiconductor laser 110 may generate a return signal, which is then sent directly to the hybrid PCB 210 via the conductive layer 217 (FIG. 2B). From the hybrid PCB 210, the return signal is sent to the stacked ground layers 202 on the second trace path, via the return wire bond 308b (FIGS. 2B, 2C). Along the second trace path, the return signal is sent to the ground trace bottom 218. From the ground trace bottom 218, the return signal may traverse the vias 216 to the ground top layer across a second trace path 21 lb, and/or may stay on the ground trace bottom 218.

[0041] Additionally, it should be understood that, while the embodiment described with regard to FIGS. 2A - 2C utilize a flex PCB, some embodiments may be configured without a ground layer top 208 and a second signal trace being constructed of flex PCB. Such configurations may instead utilize rigid PCB.

[0042] FIGS. 3 A - 3C depict another embodiment of the semiconductor laser 110 from FIG. 1, further illustrating a double layer flexible PCB mounted on top of a metal base, according to embodiments disclosed herein. More specifically, included in FIG. 3 A is a ground layer bottom 302 that is formed of a flex PCB. The ground layer bottom 302 is coupled to a signal trace top 304, also formed of a first flex PCB, via a non-conductive layer 305. The ground layer bottom 302 resides on a base 301. Additionally, the signal trace top 304 is electrically coupled to a hybrid PCB 306 via a first departure wire bond 308a, which may include one or more connections. Similarly, the hybrid PCB 306 is electrically coupled to a semiconductor laser 110 via a second departure wire bond 309, which also may include one or more connections.

[0043] FIG 3B further depicts the semiconductor laser interconnect packaging 300 from FIG 3A from a top perspective. FIG. 3B illustrates trace paths 303a and 303b, wire bonds 308a, 308b, and 309, as well as vias 311. More specifically, the connections between the hybrid PCB 306 and the signal trace top 304 and the wire bonds between the hybrid PCB and the semiconductor 110 are illustrated. Additionally, as the connection between the non- conductive layer 305 and the first departure wire bond 308a is illustrated, return wire bond 308b are also illustrated for a return signal from the semiconductor laser 110.

[0044] FIG. 3C further depicts the semiconductor laser interconnect packaging 300 from FIGS. 3A and 3B from another side perspective. As illustrated, FIG 3C more clearly shows vias extending between a ground trace top 312, which is formed by a second flex PCB and the ground layer bottom 302. This perspective further illustrates component utilized for the return signal.

[0045] For example, a signal may be received from a laser drive circuit at the signal trace top 304 (FIG. 3A). The signal may be sent along the first trace path 303a to the first departure wire bond 308a (FIGS. 3A, 3B). From the first departure wire bond 308a, the signal is sent to the hybrid PCB 306, which sends the signal to the second departure wire bonds 309, and onto the semiconductor laser 110 (FIGS. 3A, 3B). The semiconductor laser 110 creates a return signal, which is sent to the hybrid PCB 306 directly via the conductive layer 317 (FIG. 3B, 3C). The hybrid PCB 306 sends the return signal to the signal trace top 304 on the second trace path 303b. The signal then traverses the vias 311, down to the ground layer bottom 302.

[0046] It should be understood that the embodiments described with regard to FIGS. 3A - 3C are merely exemplary. More specifically, some embodiments may be configured with the base 301 formed of a conductive material. Similarly, some embodiments may include the base 301 with a non-conductive material. Other embodiments are also considered and are within the scope of this disclosure.

[0047] It should also be understood that the configurations of FIGS. 2A - 2C and 3A - 3C may be utilized to provide low impedance, low inductance, and/or low power consumption in the wavelength converted light source 100. Additionally assisting in this are the selection of wire bonds, as well as other specifications of components described herein. Table 1 shows the variation of inductance with various wire bond configurations utilized in the semiconductor interconnect packaging 200.

Inductance Due to Wire-Bonds

ctor Length (cm) self Inductance

uctor Radius (cm)

Conductor Length (cm)

Mutual Inductance

Conductor Separation (cr

•Parallel Inductors L _s i,L _s2 ,L _s3 ... add as 1/(1/Li _eff +1/L _2eff + 1/L _3eff )

•When Inductors are far apart relative to their parallel Length, L _eff = L _s

•Otherwise the Mutual Inductance must be added to the self inductance

Table 1

[0048] Based on the above and the data in Table 1, the semiconductor laser interconnect package generally utilizes three 2 mil wire bonds of length no greater than 1.5 and 2.0 mm. This implies that the inductance due to the wire bonds (e.g. wire bonds 212, 213, 308, and/or 309) will often be between 1.8 and 2.4 nano-Heneries (nH). As such, the remaining package components will likely contribute no more than 0.5 nH. This total inductance value between 2.3 and 2.9 nH becomes a factor in driving modulation bandwidth. In many cases, systems employing the wavelength converted light source 100 (FIG. 1) will be constrained to a defined voltage for the gain section of the wavelength converted light source 100 (FIG. 1).

Additionally it should be understood that there may be additional sources of inductance in the entire system including the laser driver application specific integrated circuit (ASIC), such as the drive circuit, and the physical circuit board design which connects to the wavelength converted light source 100 (FIG. 1). It is reasonable to allocate between 1 and 2 nH for the laser driver combined with additional electronics incorporated in the projector system. This brings the total inductance to between 4 and 5 nH of which 60% - 75% is directly attributable to the wavelength converted light source 100 (FIG. 1). The package inductance is directly proportional to the required overhead voltage, which in turn, directly drives overall system power consumption in the case of high speed modulation applications. Thus, the wavelength converted light source 100 (FIG. 1) contributes 60%> - 75%> to the overhead system voltage requirement and power consumption. [0049] FIG. 4 depicts a 3-dimensional view of the rigid PCB (e.g., stacked ground layers 202), according to embodiments disclosed herein. More specifically, similar to FIGS. 2 A - 2C, the shape and material distribution are shown in FIG. 4.

[0050] FIG. 5 depicts a 3-dimensional view for a flex model, according to embodiments disclosed herein. More specifically, the small (25μιη) height of the gain trace above the ground plane along with its wide width makes for a very low inductance interconnect. The average characteristic impedance of this structure is around 3Ω, consisting of approximately 240pH inductance and 26pF capacitance.

[0051] FIG. 6 illustrates a summary of inductance patterns for the wavelength converted light source 100, according to various embodiments disclosed herein. More specifically, a substrate (FR4) thickness of 6mils (approximately 150μιη) was used, as it noticeably reduced the interconnect (e.g., wire bonds 212, 308) inductance relative to a 31mil (approximately 785μιη) thickness. This is 6 mils substrate thickness is achieved by using a 4 layer rigid PCB and allows for a low cost but high performance interconnect

[0052] The total inductance of approximately 2.5nH is largely independent of frequency, rising slightly at higher frequencies. As the ultra- thin flex PCB and transmission line-type structure makes for a very low impedance interconnect. Additionally, within the package each set of wire bonds is around 0.5 nH, with the physically larger carrier to hybrid wire bonds being a bit more and the hybrid to laser wire bonds being a bit less. The "hybrid and hybrid->laser wire bonds" line is composed of roughly equally quantities of hybrid and bond wire inductance. Overall, the circuit impedance is not particularly dominated by any one component.

[0053] While the circuit impedance is not dominated by any one component, it turns out that the time-domain response is mostly influenced by the flex PCB. As a very low-impedance structure, given sufficient high-frequency energy it can resonate if driven by and temiinated by high impedances.

[0054] FIG. 7 illustrates a graphical representation of a summary of inductance parameters, according to various embodiments disclosed herein. More specifically, the step-response with a 2Ω source and load resistance is show below in blue, along with a reference ("perfect") step driving an ideal resistor in purple: The 10%-90% rise time is approximately 1.25ns.

[0055] FIG. 8 depicts a circuit diagram, such as may be simulated for the embodiment from FIGS. 2A - 2C. More specifically in a particular embodiment, FIG. 8 may be utilized to determine specifications for implementation of the semiconductor laser interconnect packaging 200 in FIGS. 2A - 2C.