There are indeed photoreceptors on plant to sense light. Flowering plants use the amount of light to decide when to blossom. There are three categories of flowering plants: long-day plant, short-day plant, and day-neutral plant.

Long-day plants need the daylight to exceed a threshold to flower; short-day plants need the darkness to exceed a threshold; the flowering of day-neutral plants is not really affected by light.

Biologists have carried out interrupted night experiment to study the flowering behavior. In such experiment, the plants are exposed to enough light for short-day plants to flower but not the long-day plant. However, if the dark period is interrupted by a flash of light, the long-day plants can then flower while the short-day plants cannot. A strobe of light during the dark therefore does induce changes to a plant.

Now back to the plant to plant communication, currently there are two known methods of plant communication: volatile organic compounds and electric signal. We do not know if plant communicates through light reflection.

However, science is all about exploring the unknown. Perhaps you can design an experiment to see if it is the case. There are the questions you might want to consider: How can we test this hypothesis? Suppose plants do communicate through light reflection, what prediction can we make? What kind of metric can we use to measure the communication?

As far as we know, trees do not communicate with each-other using light.

Some trees do communicate with each-other, but they do it by releasing chemicals into the air that the other trees can 'smell'. The colors of light that trees reflect is determined by the pigments in their leaves, and those pigments are used for photosynthesis. Trees cannot selectively choose to reflect some colors but not others, thereby being able to communicate.

Police lights probably don't shine on plants long enough to affect their growth. It's somewhat like my cell phone charger with solar panels. Many hours in a sunny window hardly charged the charger at all.

Here is a link about light color vs plant growth.

"The color of light DOES affect plant growth, but the effect is more noticeable under low light intensity. Red & blue light are most effective for plant growth, while yellow & green have minimal effect. UV light can damage plants, causing leaves to burn. Growers often use supplemental light to optimize plant growth."

Trees probably don't communicate with each other through colors. Think of how different colors look in the light vs in the shade. Here's a link with pictures of how trees might communicate:

From here: “Yes, in a sense. Some research has shown that trees have a unique way of expressing themselves to one another. About twenty years ago, an ecologist named Suzanne Simard “discovered that trees communicate their needs and send each other nutrients via a network of latticed fungi buried in the soil.”Jan 25, 2019"