In their first semester, some Cornell engineering students don’t just learn about lasers in class — they build them.
This hands-on intensity is exactly what stood out to students in ENGRI 1100: “Lasers and Photonics.”
“I didn’t really know anything about applied and engineering physics. I just knew I liked physics and I liked engineering and building stuff,” said Annelise Gross ’29. “And then I saw that in this class we were able to build the nitrogen laser and we did it over six weeks. And it was really incredible to get some hands-on experience.”
Taught by Prof. Jeffrey Moses Ph.D. ’07, applied and engineering physics, ENGRI 1100 gives first-years in the College of Engineering the chance to study light. Photonics is the science of creating, moving and detecting light as particles called photons.
The class is one of Cornell’s longest-running introductory engineering courses, according to AEP Director of Instructional Labs Jon Velazquez, and one of two within the School of Applied and Engineering Physics. It aims to introduce students to the fundamental questions relating to light, matter and quantum mechanics through working with and learning about the applications of lasers.
Offered in the fall and spring, ENGRI 1100 often serves as the first course in the AEP pathway — a specialized focus area tailored to specific career goals — which trains students in diverse applied physics disciplines. Featuring two lectures and a lab every week, ENGRI 1100 aims to help students bridge the gap between theory and practice.
In the construction lab, students build their own nitrogen laser system, which uses nitrogen gas to produce pulses of ultraviolet light. The demonstration explores how light behaves, allowing students to visualize concepts such as polarization, reflection and diffraction.
“At the beginning of the semester, the students don’t really have lots of knowledge,” said Yanzhou Wu, a first-year graduate student and teaching assistant for the course. “In demo lab, if [a] student can see stuff by themselves, it’s easier [for] them to understand how it works.”
Wu helps guide students through experiments that turn complex ideas into something visible. Prior to each lab, he gives a short presentation to explain key concepts and bridge necessary knowledge gaps.
Early labs explore physical phenomena, such as the reflection of polarized light— light where waves vibrate in a singular direction, rather than all directions. . Later in the semester, students have the opportunity to experiment with holograms and fiber optics.
Velazquez runs similar presentations at the beginning of the construction lab.
“I have to find out where [the students] are, in terms of what they already know, that I can build on,” Velazquez said.
Students work in groups, each responsible for one of three electronic components used to assemble a nitrogen laser from scratch.
“We were split into three groups, and each group was given a diagram of what to build,” Gross said. “And then our teacher gave us a lot of freedom to make the choices for ourselves and how we wanted to go about it.”
Students then complete presentations on the component they are responsible for. According to Velazquez, the presentation element is intended to provide students with practical experience speaking in front of their peers and to push them to truly understand how the laser works.
“It’s very open ended,” Gross said. “The benefit of that is that students are really pushed to learn [by] themselves. The best thing about the more hands-off approach in the lab was that we were given the freedom to really fail.”
By the end of the four-week construction lab, each group of students has a functioning laser, which is tested by measuring the speed of light.
“Everyone knows what the speed of light is, virtually,” Velazquez said. “So we can check and see if we did a good job measuring it.”
Though students may not approach engineering with a deep interest in the underlying principles, ENGRI 1100 supports students in understanding more practical aspects of how things operate.
“[Students] get the underlying physics, they get the hands-on aspect of actually building the device and then I also talk about applications," Velazquez said.
The applied aspect of the course is useful because beyond academia, photonics is widely applicable in modern life. The same principles students test in class drive the technology behind phone screens, data transmission, medical imaging systems and even sunglasses. By being immersed in examples of light and photonics in action, students get a view into how such innovations shape nearly every field of engineering while having fun in the process.
“In lecture, we go in depth about wave-particle duality,” Gross said. “And then in the lab, [we’re] really seeing all these different parts come together, and then, boom, let there be light — It’s absolutely mind blowing.”
